Sitagliks^® MET (Tablets) Instructions for Use

Marketing Authorization Holder

Izvarino Pharma LLC (Russia)

ATC Code

A10BD07 (Metformin and Sitagliptin)

Active Substances

Metformin (Rec.INN registered by WHO)

Sitagliptin (Rec.INN registered by WHO)

Dosage Form

Sitagliks® MET

Film-coated tablets 1000 mg+50 mg

Dosage Form, Packaging, and Composition

Film-coated tablets

10 pcs. – blister packs (10 pcs.) – cardboard packs (100 pcs.) – By prescription
10 pcs. – blister packs (2 pcs.) – cardboard packs (20 pcs.) – By prescription
10 pcs. – blister packs (3 pcs.) – cardboard packs (30 pcs.) – By prescription
10 pcs. – blister packs (6 pcs.) – cardboard packs (60 pcs.) – By prescription
10 pcs. – blister packs (9 pcs.) – cardboard packs (90 pcs.) – By prescription

Clinical-Pharmacological Group

Oral hypoglycemic drug

Pharmacotherapeutic Group

Drugs for the treatment of diabetes mellitus; hypoglycemic drugs, other than insulins; combinations of oral hypoglycemic drugs

Pharmacological Action

The drug is a combination of two hypoglycemic drugs with complementary mechanisms of action, intended to improve glycemic control in patients with type 2 diabetes mellitus: sitagliptin, an inhibitor of the dipeptidyl peptidase-4 (DPP-4) enzyme, and metformin, a representative of the biguanide class.

Metformin

Metformin is a hypoglycemic drug that increases glucose tolerance in patients with type 2 diabetes mellitus by reducing basal and postprandial blood glucose concentrations. Its pharmacological mechanisms of action differ from those of other classes of oral hypoglycemic drugs.

Metformin reduces hepatic glucose synthesis, reduces intestinal glucose absorption, and increases insulin sensitivity by enhancing peripheral glucose uptake and utilization. Unlike sulfonylurea derivatives, Metformin does not cause hypoglycemia in patients with type 2 diabetes mellitus or in healthy individuals (except under certain circumstances) and does not cause hyperinsulinemia. During treatment with metformin, insulin secretion does not change, while fasting insulin concentration and the daily plasma insulin concentration may decrease.

Sitagliptin

Sitagliptin is an orally active, highly selective inhibitor of the DPP-4 enzyme, intended for the treatment of type 2 diabetes mellitus. The pharmacological effects of the class of DPP-4 inhibitor drugs are mediated by the activation of incretins. By inhibiting DPP-4, Sitagliptin increases the concentration of two known active hormones of the incretin family: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Incretins are part of the intrinsic physiological system regulating glucose homeostasis. At normal or elevated blood glucose concentrations, GLP-1 and GIP promote increased synthesis and secretion of insulin by pancreatic β-cells. GLP-1 also suppresses glucagon secretion by pancreatic α-cells, thereby reducing hepatic glucose synthesis. This mechanism of action differs from that of sulfonylurea derivatives, which stimulate insulin release even at low blood glucose concentrations, which carries the risk of sulfonylurea-induced hypoglycemia not only in patients with type 2 diabetes mellitus but also in healthy individuals. Sitagliptin at therapeutic concentrations does not inhibit the activity of the related enzymes DPP-8 or DPP-9. Sitagliptin differs in chemical structure and pharmacological action from GLP-1 analogs, insulin, sulfonylurea derivatives or meglitinides, biguanides, peroxisome proliferator-activated receptor γ (PPARγ) agonists, alpha-glucosidase inhibitors, and amylin analogs.

Pharmacodynamics

Oral administration of a single dose of sitagliptin to patients with type 2 diabetes mellitus results in inhibition of DPP-4 enzyme activity for 24 hours, accompanied by a 2- to 3-fold increase in circulating active GLP-1 and GIP concentrations, an increase in plasma insulin and C-peptide concentrations, a decrease in glucagon concentration and fasting plasma glucose concentration, and a reduction in glycemic fluctuations after a glucose or meal load.

Administration of sitagliptin at a daily dose of 100 mg for 4-6 months significantly improved pancreatic β-cell function in patients with type 2 diabetes mellitus, as evidenced by corresponding changes in markers such as HOMA-β (homeostasis model assessment-β), the proinsulin/insulin ratio, and the assessment of pancreatic β-cell response based on a repeated meal tolerance test panel. According to phase II and III clinical studies, the glycemic control efficacy of sitagliptin when administered at a dose of 50 mg twice daily was comparable to the efficacy when administered at a dose of 100 mg once daily.

In a randomized, placebo-controlled, double-blind, four-period crossover two-day study involving healthy adult volunteers, the effect of the combination of sitagliptin and metformin compared with sitagliptin monotherapy, metformin monotherapy, or placebo on changes in plasma concentrations of active and total GLP-1 hormone and glucose after a meal was studied. The weighted mean incremental concentration of active GLP-1 hormone over 4 hours after a meal increased approximately 2-fold after taking sitagliptin alone or metformin alone compared to placebo. Simultaneous administration of sitagliptin and metformin provided an additive effect with an approximately 4-fold increase in the concentration of active GLP-1 hormone compared to placebo. Taking sitagliptin alone was accompanied by an increase only in the concentration of active GLP-1 hormone due to inhibition of the DPP-4 enzyme, while taking metformin alone was accompanied by a symmetrical increase in the concentration of active and total GLP-1 hormone. These data are consistent with the different mechanisms of action of sitagliptin and metformin responsible for increasing the concentration of active GLP-1 hormone. The results of this study also showed that it is Sitagliptin, not Metformin, that increases the concentration of active GIP hormone.

In studies involving healthy volunteers, sitagliptin administration was not accompanied by a decrease in blood glucose concentration and did not cause hypoglycemia. This suggests that the insulinotropic and glucagon-suppressive effects of the drug are glucose-dependent.

Effect on Blood Pressure

In a randomized, placebo-controlled crossover study involving patients with arterial hypertension, the simultaneous administration of antihypertensive drugs (one or more of the following: ACE inhibitors, angiotensin II receptor antagonists, slow calcium channel blockers, beta-blockers, diuretics) with sitagliptin was generally well tolerated by patients. In this category of patients, Sitagliptin demonstrated a slight hypotensive effect: at a dose of 100 mg/day, Sitagliptin reduced the mean 24-hour ambulatory systolic blood pressure by approximately 2 mm Hg compared to the placebo group. Such changes were not observed in patients with normal blood pressure.

Effect on Cardiac Electrophysiology

In a randomized, placebo-controlled crossover study, healthy volunteers took Sitagliptin orally as a single dose of 100 mg, 800 mg (8 times the recommended dose), and placebo. After taking the recommended dose (100 mg), no effect of the drug on the QTc interval duration was observed either at the time of its maximum plasma concentration or at other time points throughout the study. After taking 800 mg, the maximum placebo-corrected mean change in QTc interval duration at 3 hours after drug administration compared to baseline was 8.0 ms. Such a slight increase was assessed as clinically insignificant. After taking 800 mg, the C_max of sitagliptin in plasma was approximately 11 times higher than the corresponding value after a 100 mg dose.

In patients with type 2 diabetes mellitus, no significant changes in QTc interval duration were detected with the use of sitagliptin at a dose of 100 mg/day or 200 mg/day (based on electrocardiographic data obtained at the expected C_max of sitagliptin in plasma).

Pharmacokinetics

Results of a bioequivalence study in healthy volunteers demonstrated that the combined Metformin+Sitagliptin 500 mg+50 mg and 1000 mg+50 mg tablets are bioequivalent to the separate administration of sitagliptin and metformin at the corresponding doses.

Given the proven bioequivalence of tablets with the lowest and highest doses of metformin, the tablet with the intermediate metformin dose (Metformin+Sitagliptin) 850 mg+50 mg was also assigned bioequivalence, provided the combination of fixed drug doses in the tablet.

Metformin

The absolute bioavailability of metformin when taken on an empty stomach at a dose of 500 mg is 50-60%. Results from studies of single-dose administration of metformin tablets in doses from 500 mg to 1500 mg and from 850 mg to 2550 mg indicate a lack of dose proportionality with increasing dose, which is more likely due to reduced absorption rather than accelerated elimination. Simultaneous administration of the drug with food reduces the rate and extent of metformin absorption, as evidenced by an approximately 40% decrease in plasma C_max, an approximately 25% decrease in AUC, and a 35-minute delay in reaching C_max after a single dose of 850 mg metformin taken with food compared to the values of the corresponding parameters after taking the same dose of the drug on an empty stomach. The clinical significance of the decrease in pharmacokinetic parameter values has not been established.

The V_d of metformin after a single oral dose of 850 mg averaged 654±358 L. Metformin binds to plasma proteins to a very small extent. Metformin is partially and temporarily distributed into erythrocytes. When metformin is used at recommended doses, steady-state plasma concentrations (usually <1 µg/ml) are reached in approximately 24-48 hours. According to controlled studies, the plasma C_max of the drug did not exceed 5 µg/ml even after taking the drug at maximum doses.

After a single intravenous administration to healthy volunteers, almost the entire administered dose of metformin was excreted unchanged by the kidneys. Metabolic transformation of the drug in the liver and its excretion with bile do not occur.

The renal clearance of metformin exceeds the glomerular filtration rate by 3.5 times, indicating active renal secretion as the main route of elimination. After metformin administration, about 90% of the absorbed drug is excreted by the kidneys within the first 24 hours, with a plasma half-life of approximately 6.2 hours; in blood, this value is prolonged to 17.6 hours, indicating the possible involvement of erythrocytes as a potential distribution compartment.

Sitagliptin

The absolute bioavailability of sitagliptin is approximately 87%. Administration of sitagliptin simultaneously with a high-fat meal does not affect the pharmacokinetics of the drug.

The mean V_d at steady state after a single intravenous administration of 100 mg sitagliptin in healthy volunteers is approximately 198 L. The fraction of sitagliptin reversibly bound to plasma proteins is relatively small (38%).

Approximately 79% of sitagliptin is excreted unchanged by the kidneys; metabolic transformation of the drug is minimal.

After oral administration of ¹⁴C-labeled sitagliptin, approximately 16% of the administered radioactivity was excreted as metabolites of sitagliptin. Trace concentrations of 6 metabolites of sitagliptin were detected, which do not contribute to the plasma DPP-4 inhibitory activity of sitagliptin. In in vitro studies, the cytochrome isoenzymes CYP3A4 and CYP2C8 were identified as the main enzymes involved in the limited metabolism of sitagliptin.

After oral administration of ¹⁴C-labeled sitagliptin to healthy volunteers, almost all of the administered radioactivity was eliminated from the body within a week, including 13% via the intestine and 87% via the kidneys; the mean T_1/2 of sitagliptin after oral administration of a 100 mg dose is approximately 12.4 hours, and renal clearance is approximately 350 ml/min.

Elimination of sitagliptin occurs primarily through renal excretion via an active tubular secretion mechanism. Sitagliptin is a substrate of the human organic anion transporter-3 (hOAT-3), which is involved in the renal elimination process of sitagliptin. The clinical significance of hOAT-3 involvement in sitagliptin transport has not been established. P-glycoprotein may be involved in the renal elimination of sitagliptin (as a substrate); however, the P-glycoprotein inhibitor cyclosporine does not reduce the renal clearance of sitagliptin.

Pharmacokinetics in Specific Patient Groups

The pharmacokinetics of sitagliptin in patients with type 2 diabetes mellitus is similar to that in healthy individuals. With preserved renal function, the pharmacokinetic parameters after single and repeated doses of metformin in patients with type 2 diabetes mellitus and healthy individuals are the same, and no accumulation of the drug occurs at therapeutic doses.

The drug should not be prescribed to patients with renal failure. In patients with moderate renal impairment, an approximately 2-fold increase in the plasma AUC of sitagliptin was noted, and in patients with severe and end-stage renal failure (on hemodialysis), the increase in AUC value was 4-fold compared to control values in healthy volunteers. In patients with reduced renal function (by glomerular filtration rate), the T_1/2 of the drug is prolonged, and renal clearance decreases proportionally to the decrease in glomerular filtration rate.

In patients with moderate hepatic impairment (7-9 points on the Child-Pugh scale), the mean AUC and C_max values of sitagliptin after a single 100 mg dose increased by approximately 21% and 13%, respectively, compared to healthy individuals. This difference is not clinically significant. There are no clinical data on the use of sitagliptin in patients with severe hepatic impairment (more than 9 points on the Child-Pugh scale). However, based on the predominantly renal route of elimination of the drug, significant changes in the pharmacokinetics of sitagliptin in patients with severe hepatic impairment are not predicted.

According to an analysis of pharmacokinetic data from phase I and II clinical studies, gender did not have a clinically significant effect on the pharmacokinetic parameters of sitagliptin. The pharmacokinetic parameters of metformin did not differ significantly between healthy volunteers and patients with type 2 diabetes mellitus based on gender. According to controlled clinical studies, the hypoglycemic effects of metformin were similar in men and women.

According to a population pharmacokinetic analysis of data from phase I and II clinical studies, patient age did not have a clinically significant effect on the pharmacokinetic parameters of sitagliptin. The concentration of sitagliptin in elderly patients (65-80 years) was approximately 19% higher than in young patients. Limited data from controlled pharmacokinetic studies of metformin in healthy elderly volunteers suggest that the total plasma clearance of the drug is reduced, T_1/2 is prolonged, and the C_max value is increased compared to young healthy individuals. These data indicate that age-related changes in the pharmacokinetics of the drug are due to a decrease in renal excretory function. Treatment with the drug is not indicated for the elderly aged >80 years, except for individuals whose glomerular filtration rate indicates that renal function is not reduced.

According to an analysis of pharmacokinetic data from phase I and II clinical studies, race did not have a clinically significant effect on the pharmacokinetic parameters of sitagliptin, including in Caucasians, Mongoloids, Hispanics, and other ethnic and racial groups. According to controlled studies of metformin in patients with type 2 diabetes mellitus, the hypoglycemic effect of the drug was comparable in Caucasians, Blacks, and Hispanics.

According to complex and population analyses of pharmacokinetic parameters from phase I and II clinical studies, BMI did not have a clinically significant effect on the pharmacokinetic parameters of sitagliptin.

Extended-Release Tablets

Results from a study involving healthy volunteers showed that the combined drug (Metformin and Sitagliptin) in the form of extended-release tablets in dosages of 500 mg+50 mg and 1000 mg+100 mg is bioequivalent to the combination of single-drug sitagliptin and extended-release metformin in the corresponding dosages. Bioequivalence was also demonstrated between taking 2 extended-release tablets of 500 mg+50 mg and 1 extended-release tablet of 1000 mg+100 mg.

In a crossover study involving healthy volunteers, the AUC and C_max values of sitagliptin and the AUC value of metformin after taking 1 extended-release tablet of 500 mg+50 mg and after taking 1 standard-release tablet of 500 mg+50 mg were similar. After taking 1 extended-release tablet of 500 mg+50 mg, the mean C_max value of metformin decreased by 30%, and the median time to maximum concentration (T_max) increased by 4 hours compared to the corresponding values after taking 1 standard-release tablet of 500 mg+50 mg, which is consistent with the expected extended-release mechanism of metformin. When healthy adult volunteers took 2 extended-release tablets of 1000 mg+50 mg once daily in the evening with food for 7 days, the C_ss of sitagliptin and metformin in the blood was reached on days 4 and 5, respectively. The median T_max of sitagliptin and metformin at steady state after administration was about 3 hours and 8 hours, respectively, while the median T_max of sitagliptin and metformin after taking 1 standard-release tablet was 3 hours and 3.5 hours, respectively.

After taking the drug in the form of extended-release tablets simultaneously with a high-fat breakfast, the AUC of sitagliptin did not change. The mean C_max decreased by 17%, although the median T_max did not change compared to the corresponding parameters when the drug was taken on an empty stomach. After taking the drug in the form of extended-release tablets with a high-fat breakfast, the AUC of metformin increased by 62%, the C_max of metformin decreased by 9%, and the median T_max of metformin increased by 2 hours compared to the corresponding parameters when the drug was taken on an empty stomach.

Administration of a monotherapy metformin extended-release preparation simultaneously with low-fat and high-fat food increased the systemic exposure to metformin (measured by AUC value) by approximately 38% and 73%, respectively, compared to the corresponding parameter value when the drug was taken on an empty stomach. Ingestion of any food, regardless of its fat content, increased the T_max of metformin by approximately 3 hours, while the C_max value did not change.

Indications

Monotherapy

As initial therapy for patients with type 2 diabetes mellitus to improve glycemic control, if diet and exercise do not achieve adequate control; as an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus who have not achieved adequate control on monotherapy with metformin or sitagliptin, or after unsuccessful combination therapy with two drugs.

Combination Therapy

For patients with type 2 diabetes mellitus to improve glycemic control in combination with sulfonylurea derivatives (triple combination: Metformin + Sitagliptin + sulfonylurea derivative), when diet and exercise in combination with two of these three drugs (Metformin, Sitagliptin, or sulfonylurea derivatives) do not lead to adequate glycemic control; in combination with thiazolidinediones (PPARγ receptor agonists), when diet and exercise in combination with two of these three drugs (Metformin, Sitagliptin, or thiazolidinedione) do not lead to adequate glycemic control; in combination with insulin, when diet and exercise in combination with insulin do not lead to adequate glycemic control.

ICD codes

Dosage Regimen

The dosage regimen of the drug is selected individually, based on current therapy, efficacy, and tolerability, but not exceeding the maximum recommended daily dose of metformin 2000 mg and sitagliptin 100 mg.

The drug in the form of standard-release tablets is produced in the following dosages: 850 mg metformin + 50 mg sitagliptin and 1000 mg metformin + 50 mg sitagliptin. The drug is taken 2 times/day with meals.

The drug in the form of extended-release tablets is produced in dosages of 500 mg + 50 mg, 1000 mg + 50 mg, and 1000 mg + 100 mg. The drug with a dosage of 500 mg + 50 mg or 1000 mg + 50 mg should be taken as 2 tablets simultaneously once a day; 1000 mg + 100 mg – 1 tablet once a day, with meals, preferably in the evening. To ensure the extended release of metformin, the tablet should not be split, broken, crushed, or chewed before swallowing. There have been reports of finding incompletely dissolved tablets in stool. It is not known whether this material contained active substances. The patient should be warned to inform the attending physician about cases of repeated detection of tablets in the stool. Upon receiving such reports, the attending physician should assess the adequacy of the patient’s glycemic control. Extended-release tablets, film-coated.

The dose of the drug should be increased gradually to reduce gastrointestinal adverse reactions associated with the action of metformin.

The initial dose of the drug depends on the current hypoglycemic therapy.

In patients with type 2 diabetes mellitus with inadequate glycemic control on diet and exercise, the recommended starting dose is 500 mg metformin + 50 mg sitagliptin twice a day. Subsequently, the dose can be increased to 1000 mg metformin + 50 mg sitagliptin twice a day.

The starting dose of the drug in the form of extended-release tablets should be equivalent to 1000 mg of metformin and 100 mg of sitagliptin. In patients taking the drug at the above dose and who have not achieved adequate glycemic control, a gradual (to reduce the number of gastrointestinal adverse reactions associated with the action of metformin) increase in the drug dose up to the maximum recommended daily dose of metformin 2000 mg is possible.

In patients who have not achieved adequate control on metformin monotherapy, the recommended initial dose of the drug should be equivalent to 100 mg of sitagliptin and the taken dose of metformin.

In patients who have not achieved adequate control on sitagliptin monotherapy, the recommended initial dose is 500 mg metformin + 50 mg sitagliptin twice a day. Subsequently, the dose may be increased to 1000 mg metformin + 50 mg sitagliptin twice a day. The recommended initial dose of the drug in the form of extended-release tablets should be equivalent to 1000 mg of metformin and 100 mg of sitagliptin. The metformin dose may be adjusted to achieve adequate glycemic control. It should be considered that to reduce the number of gastrointestinal adverse reactions associated with the action of metformin, the metformin dose must be increased gradually. For patients with renal impairment taking an adjusted dose of sitagliptin in monotherapy due to this condition, treatment with the drug is contraindicated.

In patients taking a combination of Sitagliptin and Metformin drugs, when switching from combination therapy with sitagliptin and metformin, the initial dose of the drug may be equivalent to the doses of sitagliptin and metformin being taken.

In patients taking two of the listed three hypoglycemic drugs (Sitagliptin, Metformin, or sulfonylurea derivatives), the initial dose of the drug should provide the recommended therapeutic daily dose of sitagliptin 100 mg. When determining the starting dose of metformin, the level of glycemic control and the current (if the patient is taking Metformin) dose of metformin should be taken into account. It should also be considered that to reduce the number of gastrointestinal adverse reactions associated with the action of metformin, the metformin dose must be increased gradually. For patients taking or starting to take a sulfonylurea derivative, a reduction in the dose of the sulfonylurea derivative may be required to reduce the risk of sulfonylurea-induced hypoglycemia.

In patients taking two of the listed three hypoglycemic drugs (Sitagliptin, Metformin, or PPARγ receptor agonists (thiazolidinediones)), the initial dose of the drug should correspond to a daily dose of sitagliptin 100 mg. When determining the starting dose of metformin, the level of glycemic control and the current (if the patient is taking Metformin) dose of metformin should be taken into account. It should also be considered that to reduce the number of gastrointestinal adverse reactions associated with the action of metformin, the dose must be increased gradually.

In patients taking two of the listed three hypoglycemic drugs (Sitagliptin, Metformin, or insulin), the initial dose of the drug should correspond to a daily dose of sitagliptin 100 mg. When determining the starting dose of metformin, the level of glycemic control and the current (if the patient is taking Metformin) dose of metformin should be taken into account. It should also be considered that to reduce the number of gastrointestinal adverse reactions associated with the action of metformin, the metformin dose must be increased gradually. For patients receiving or starting to receive insulin therapy, a reduction in the insulin dose may be required to reduce the risk of insulin-induced hypoglycemia.

No specific studies have been conducted to evaluate the safety and efficacy of therapy with the drug in patients previously treated with other oral hypoglycemic agents and switched to therapy with the combination drug. Any changes in the therapy of type 2 diabetes mellitus should be carried out with caution and under the control of relevant parameters, taking into account possible changes in glycemic control.

The drug should not be used in patients with renal failure or renal dysfunction, for example, with serum creatinine concentration >1.5 mg/dL (in men) and >1.4 mg/dL (in women) respectively, or with decreased CrCl.

The use of the drug in patients with severe hepatic impairment is not recommended.

The drug should be used with caution in elderly patients, since Metformin and Sitagliptin are excreted by the kidneys. Monitoring of renal function is necessary to prevent the development of Metformin-associated lactic acidosis, especially in elderly patients.

The safety of the drug in children and adolescents under 18 years of age has not been studied.

Adverse Reactions

In studies, combination treatment with sitagliptin and metformin was generally well tolerated by patients with type 2 diabetes mellitus. The incidence of side effects with combination treatment with sitagliptin and metformin was comparable to the incidence with metformin in combination with placebo.

Combination treatment with sitagliptin and metformin

Initial therapy. In a 24-week placebo-controlled factorial study of initial therapy, in the group of patients taking Sitagliptin at a dose of 50 mg twice a day in combination with metformin at a dose of 500 mg or 1000 mg twice a day, the following treatment-related adverse reactions were observed with an incidence of ≥1% and more frequently compared to the groups of monotherapy with metformin at a dose of 500 mg or 1000 mg twice a day or sitagliptin at a dose of 100 mg once a day, or placebo: diarrhea – 3.5% (3.3%, 0.0%, 1.1% – in the metformin monotherapy, sitagliptin monotherapy, and placebo groups, respectively), nausea – 1.6% (2.5%, 0.0%, 0.6%), dyspepsia – 1.3% (1.1%, 0.0% and 0.0%), flatulence – 1.3% (0.5%, 0.0% and 0.0%), vomiting – 1.1% (0.3%, 0.0% and 0.0%), headache – 1.3% (1.1%, 0.6% and 0.0%) and hypoglycemia – 1.1% (0.5%, 0.6% and 0.0%).

Addition of sitagliptin to current metformin therapy. In a 24-week placebo-controlled study, Sitagliptin was added to ongoing metformin therapy: 464 patients took Metformin with the addition of sitagliptin at a dose of 100 mg once a day, and 237 patients took placebo and Metformin. The only treatment-related adverse reaction in the sitagliptin and metformin treatment group, observed with an incidence of ≥1% and exceeding that in the placebo group, was nausea (1.1% – in the combination therapy group with metformin and sitagliptin, 0.4% – in the placebo with metformin group).

Hypoglycemia and gastrointestinal adverse reactions. In placebo-controlled studies of combination therapy with sitagliptin and metformin, the incidence of hypoglycemia (regardless of causality) in patients receiving the combination of sitagliptin and metformin was comparable to the incidence in the group of patients taking Metformin in combination with placebo. In the initial therapy study with sitagliptin and metformin, the incidence of hypoglycemia was 1.6% in the combination therapy group with metformin and sitagliptin and 0.8% in the metformin therapy group. In the study of metformin therapy with the addition of sitagliptin, the incidence of hypoglycemia was 1.3% in the combination therapy group with metformin and sitagliptin and 2.1% in the metformin therapy group. In the initial therapy study with sitagliptin and metformin, the incidence of tracked gastrointestinal adverse reactions (regardless of causality) in patients receiving the combination of sitagliptin and metformin was comparable to the incidence in the group of patients taking Metformin with placebo: diarrhea (7.5% – in the combination therapy group with sitagliptin and metformin, 7.7% – in the metformin group), nausea (4.8%, 5.5%), vomiting (2.1%, 0.5%), abdominal pain (3.0%, 3.8%). In the study of metformin therapy with the addition of sitagliptin, the incidence of tracked gastrointestinal adverse reactions (regardless of causality) in patients receiving the combination of sitagliptin and metformin was comparable to the incidence in the group of patients taking Metformin with placebo: diarrhea (2.4% – in the combination therapy group with sitagliptin and metformin, 2.5% – in the metformin group), nausea (1.3%, 0.8%), vomiting (1.1%, 0.8%), abdominal pain (2.2%, 3.8%).

In all studies, adverse reactions in the form of hypoglycemia were recorded based on all reports of clinically significant symptoms of hypoglycemia. Additional measurement of blood glucose concentration was not required.

Combination treatment with sitagliptin, metformin and a sulfonylurea derivative

In a 24-week placebo-controlled study, when adding sitagliptin at a daily dose of 100 mg to current combination therapy with glimepiride at a daily dose of ≥4 mg and metformin at a daily dose of ≥1500 mg, the following treatment-related adverse reactions were observed with an incidence of ≥1% in the sitagliptin treatment group and more frequently than in the placebo group: hypoglycemia (13.8% – in the sitagliptin group and 0.9% – in the placebo group) and constipation (1.7% and 0.0%).

Combination therapy with sitagliptin, metformin and a PPARγ agonist

In a placebo-controlled study, when adding sitagliptin at a daily dose of 100 mg to current combination therapy with rosiglitazone and metformin at 18 weeks of treatment, the following treatment-related adverse reactions were observed with an incidence of ≥1% in the sitagliptin treatment group and more frequently than in the placebo group: headache (2.4% – in the sitagliptin group, 0.0% – in the placebo group), diarrhea (1.8%, 1.1%), nausea (1.2%, 1.1%), hypoglycemia (1.2%, 0.0%), vomiting (1.2%, 0.0%). At 54 weeks of therapy, the following treatment-related adverse reactions were observed with an incidence of ≥1% in the sitagliptin treatment group and more frequently than in the placebo group: headache (2.4%, 0.0%), hypoglycemia (2.4%, 0.0%), upper respiratory tract infections (1.8%, 0.0%), nausea (1.2%, 1.1%), cough (1.2%, 0.0%), fungal skin infections (1.2%, 0.0%), peripheral edema (1.2%, 0.0%), vomiting (1.2%, 0.0%).

Combination therapy with sitagliptin, metformin and insulin

In a 24-week placebo-controlled study, when adding sitagliptin at a daily dose of 100 mg to current combination therapy with metformin at a daily dose of ≥1500 mg and insulin at a constant dose, the only treatment-related adverse reaction observed with an incidence of ≥1% in the treatment group with sitagliptin and more frequently than in the placebo group was hypoglycemia (10.9% – in the sitagliptin group, 5.2% – in the placebo group). In another 24-week study, in which patients received Sitagliptin as add-on therapy during ongoing insulin therapy intensification (with or without metformin), the only treatment-related adverse reaction observed with an incidence of ≥1% in the sitagliptin and metformin therapy group and more frequently than in the placebo and metformin group was vomiting (1.1% – in the sitagliptin and metformin therapy group, 0.4% – in the placebo and metformin group).

Pancreatitis

According to a pooled analysis of the results of 19 double-blind randomized clinical trials, which included data from patients receiving Sitagliptin at a daily dose of 100 mg or a corresponding control drug (active or placebo), the incidence of unconfirmed acute pancreatitis cases was 0.1 case per 100 patient-years of treatment in each group.

No clinically significant deviations in vital signs or ECG (including QTc interval duration) were observed during combination therapy with sitagliptin and metformin.

Adverse reactions due to sitagliptin intake

No adverse reactions due to sitagliptin intake were observed in patients with an incidence of ≥1%.

Adverse reactions due to metformin intake

Adverse reactions (regardless of causality), observed with an incidence of >5% in patients in the metformin extended-release therapy group and more frequently than in the placebo group, are diarrhea, nausea/vomiting, flatulence, asthenia, dyspepsia, abdominal discomfort, and headache.

Effect on the cardiovascular system (TECOS safety study)

The clinical study to assess the effect of sitagliptin on the cardiovascular system (TECOS) included 7332 patients with type 2 diabetes mellitus receiving Sitagliptin at a daily dose of 100 mg (or 50 mg/day if the baseline estimated glomerular filtration rate (eGFR) was ≥30 and <50 ml/min/1.73 m²), and 7339 patients receiving placebo, among patients who received at least one dose of the study drug. The study drug (Sitagliptin or placebo) was prescribed in addition to baseline treatment aimed at controlling cardiovascular risk factors and achieving the target level of glycated hemoglobin (HbA1c), according to local standards of patient management. The study included 2004 patients aged ≥75 years, 970 of whom received Sitagliptin, 1034 received placebo. Overall, the incidence of serious adverse events in the group of patients receiving Sitagliptin was comparable to the incidence of adverse events in the placebo group. When assessing predefined complications due to diabetes mellitus, a comparable incidence of infections (18.4% - in the sitagliptin therapy group, 17.7% - in the placebo group) and renal failure (1.4% - in the sitagliptin therapy group and 1.5% - in the placebo group) was found between the groups. The profile of adverse events in patients aged ≥75 years was generally comparable to the profile of the general population.

In the ‘intention-to-treat’ population (patients who took at least one dose of the study drug), who were initially receiving insulin and/or a sulfonylurea drug, the incidence of severe hypoglycemia in the sitagliptin therapy group was 2.7%, in the placebo group – 2.5%. In patients not initially receiving insulin and/or a sulfonylurea derivative, the incidence of severe hypoglycemia in the sitagliptin therapy group was 1.0%, in the placebo group – 0.7%. The incidence of confirmed pancreatitis cases in patients receiving sitagliptin therapy was 0.3%, in the placebo group – 0.2%. The incidence of confirmed malignant neoplasms in patients receiving sitagliptin therapy was 3.7%, in the placebo group – 4.0%.

Post-marketing surveillance

During post-marketing monitoring of the use of the combination Metformin + Sitagliptin or its component sitagliptin, in monotherapy and/or in combination therapy with other hypoglycemic agents, additional adverse reactions have been identified. Since these data were obtained voluntarily from a population of uncertain size, it is generally not possible to reliably determine the frequency and causal relationship of these adverse reactions with therapy.

These include: hypersensitivity reactions, including anaphylaxis, angioedema, skin rash, urticaria, cutaneous vasculitis, and exfoliative skin conditions, including Stevens-Johnson syndrome, acute pancreatitis, including hemorrhagic and necrotizing forms with and without fatal outcome, worsening of renal function, including acute renal failure (sometimes requiring dialysis), upper respiratory tract infections, nasopharyngitis, constipation, vomiting, headache, arthralgia, myalgia, limb pain, back pain, skin itching, pemphigoid.

Changes in Laboratory Parameters

Sitagliptin. The frequency of laboratory parameter deviations in the sitagliptin and metformin therapy groups was comparable to the frequency in the placebo and metformin therapy groups. In most, but not all, clinical studies, a slight increase in white blood cell count (approximately 200/µL compared to placebo, mean baseline count approximately 6600/µL) was observed, due to an increase in neutrophil count. This change is not considered clinically significant.

Metformin. In controlled clinical trials of metformin lasting 29 weeks, a decrease in the normal serum cyanocobalamin (vitamin B₁₂) concentration to subnormal values without clinical manifestations was observed in approximately 7% of patients. This decrease, likely due to selective impairment of vitamin B₁₂ absorption (namely, impaired formation of the complex with intrinsic factor, the so-called complex intrinsic factor necessary for vitamin B₁₂ absorption), is very rarely accompanied by the development of anemia and is easily corrected by discontinuing metformin or by supplemental vitamin B₁₂ intake.

Contraindications

Type 1 diabetes mellitus; kidney disease or reduced renal function (with serum creatinine concentration >1.5 mg/dL and >1.4 mg/dL in men and women, respectively, or decreased CrCl (<60 mL/min), including due to cardiovascular collapse (shock), acute myocardial infarction, or septicemia; acute conditions with a risk of developing renal impairment, such as dehydration (due to diarrhea, vomiting), fever, severe infectious diseases, hypoxic conditions (shock, sepsis, renal infections, bronchopulmonary diseases); acute or chronic metabolic acidosis, including diabetic ketoacidosis (with or without coma); clinically significant manifestations of acute and chronic diseases that can lead to tissue hypoxia (including cardiac or respiratory failure, acute myocardial infarction); major surgical operations and trauma when insulin therapy is indicated; hepatic failure, impaired liver function; chronic alcoholism, acute alcohol poisoning; pregnancy, lactation; lactic acidosis (including in history); use for at least 48 hours before and 48 hours after radioisotope or X-ray studies with the administration of iodine-containing contrast medium; adherence to a hypocaloric diet (less than 1000 kcal/day); children and adolescents under 18 years of age; hypersensitivity to sitagliptin, metformin, or any component of the drug.

With caution

Since the primary route of elimination for sitagliptin and metformin is the kidneys, and because renal excretory function decreases with age, caution should be exercised when prescribing the drug to elderly patients. The dose should be carefully selected and renal function regularly monitored to prevent the development of Metformin-associated lactic acidosis.

According to clinical studies, the efficacy and safety of sitagliptin in elderly (over 65 years) patients were comparable to those in younger (under 65 years) patients.

The number of elderly patients among participants in controlled metformin studies was insufficient to draw a formal conclusion about age-related differences in the drug’s efficacy and safety, although available data did not indicate such differences. Since Metformin is primarily excreted by the kidneys, and the risk of serious adverse reactions increases with impaired renal function, the drug should be prescribed only to patients with confirmed normal renal function.

Use in Pregnancy and Lactation

No adequate and well-controlled studies of the drug or its components have been conducted in pregnant women; therefore, data on its safety during pregnancy are not available. The drug, like other oral hypoglycemic agents, is not recommended for use during pregnancy.

No experimental studies of the combination drug have been conducted to assess its effects on reproductive function. Only available data from studies of sitagliptin and metformin are provided.

No teratogenic effects of sitagliptin were observed during organogenesis following oral administration to rats at doses up to 250 mg/kg or to rabbits at doses up to 125 mg/kg, which exceeds the human exposure at the recommended adult daily dose of 100 mg by 32 and 22 times, respectively. A slight increase in the incidence of rib malformations (absence, hypoplasia, wavy ribs) was observed in the offspring of rats following oral administration of the drug at daily doses of 1000 mg/kg to pregnant females, which exceeds the human exposure at the recommended adult daily dose of 100 mg by approximately 100 times. Oral administration of the drug to female rats at a daily dose of 1000 mg/kg resulted in a slight decrease in body weight in offspring of both sexes during the lactation period and a decrease in weight gain after the end of lactation in males. However, animal reproduction studies are not always predictive of human response.

No teratogenic effects of metformin were observed following administration to rats and rabbits at daily doses up to 600 mg/kg, which exceeds the plasma exposure in humans by 2 and 6 times (in rats and rabbits, respectively) after administration of the maximum recommended daily therapeutic dose of 2000 mg. Determination of metformin concentration in fetal plasma indicates partial permeability of the placental barrier.

Experimental studies on the secretion of the components of the combination drug into breast milk have not been conducted. According to studies of the individual drugs, both Sitagliptin and Metformin are secreted into the milk of lactating rats. There are no data on the secretion of sitagliptin into human breast milk. Therefore, the drug should not be prescribed during lactation.

Use in Hepatic Impairment

The use of the drug is contraindicated in hepatic failure and impaired liver function.

Use in Renal Impairment

The use of the drug is contraindicated in kidney disease or reduced renal function (with serum creatinine concentration >1.5 mg/dL and >1.4 mg/dL in men and women, respectively, or decreased CrCl (<60 mL/min).

Pediatric Use

The use of the drug is contraindicated in children and adolescents under 18 years of age.

Geriatric Use

Caution should be exercised when prescribing the drug to elderly patients.

Special Precautions

Pancreatitis

There have been postmarketing reports of acute pancreatitis, including fatal and nonfatal hemorrhagic or necrotizing pancreatitis, in patients taking Sitagliptin. Patients should be informed of the characteristic symptoms of acute pancreatitis: persistent, severe abdominal pain. Clinical manifestations of pancreatitis resolved after discontinuation of sitagliptin. If pancreatitis is suspected, the drug and other potentially suspect drugs should be discontinued.

Monitoring of Renal Function

Metformin and Sitagliptin are primarily excreted by the kidneys. The risk of metformin accumulation and lactic acidosis increases with the degree of renal impairment; therefore, the drug should not be prescribed to patients with serum creatinine concentrations above the upper limit of normal for their age. In elderly patients, due to age-related decline in renal function, the minimum effective dose of the drug should be used to achieve adequate glycemic control. In elderly patients, especially those aged ≥80 years, regular monitoring of renal function should be performed. Normal renal function should be confirmed by appropriate tests before starting therapy with the drug and at least annually thereafter. In patients at risk of renal dysfunction, renal function should be monitored more frequently, and if symptoms of renal dysfunction appear, the drug should be discontinued.

Risk of Hypoglycemia with Concomitant Use of Sulfonylureas or Insulin

As with other hypoglycemic agents, hypoglycemia has been observed when sitagliptin and metformin are used in combination with insulin or sulfonylureas. To reduce the risk of sulfonylurea- or insulin-induced hypoglycemia, a reduction in the dose of the sulfonylurea or insulin may be considered.

Sitagliptin

Risk of Hypoglycemia with Concomitant Use of Sulfonylureas or Insulin

In clinical studies of sitagliptin, both as monotherapy and in combination with agents not associated with hypoglycemia (i.e., metformin or PPARγ agonists – thiazolidinediones), the incidence of hypoglycemia in patients taking Sitagliptin was similar to that in patients taking placebo. As with other hypoglycemic agents, hypoglycemia has been observed when sitagliptin is used in combination with insulin or sulfonylureas. To reduce the risk of sulfonylurea- or insulin-induced hypoglycemia, a reduction in the dose of the sulfonylurea or insulin may be considered.

Hypersensitivity Reactions

There have been postmarketing reports of serious hypersensitivity reactions in patients treated with sitagliptin, a component of the drug. These reactions include anaphylaxis, angioedema, and exfoliative skin conditions, including Stevens-Johnson syndrome. Because these reports are from a population of uncertain size and are voluntary, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure. These reactions occurred within the first 3 months after initiation of treatment with sitagliptin, with some reports occurring after the first dose. If a hypersensitivity reaction is suspected, discontinue the drug, assess for other potential causes for the event, and institute alternative treatment for diabetes.

Metformin

Lactic Acidosis

Lactic acidosis is a rare but serious metabolic complication that can occur due to metformin accumulation during treatment with the drug, and its fatality rate is approximately 50%. Lactic acidosis can also occur in the context of certain pathophysiological conditions, particularly diabetes mellitus or any other condition associated with significant tissue hypoperfusion and hypoxemia. Lactic acidosis is characterized by elevated blood lactate levels (>5 mmol/L), decreased blood pH, electrolyte disturbances with an increased anion gap, and an increased lactate/pyruvate ratio. If metformin is implicated in the lactic acidosis, its plasma level is usually >5 µg/mL.

Available data suggest that the incidence of lactic acidosis during metformin therapy is very low (approximately 0.03 cases per 1000 patient-years, with a fatality rate of about 0.015 cases per 1000 patient-years). In over 20,000 patient-years of metformin therapy in clinical trials, no cases of lactic acidosis were reported. Reported cases have occurred primarily in diabetic patients with significant renal impairment, including significant renal disease and renal hypoperfusion, often in conjunction with multiple concomitant medical/surgical conditions and polypharmacy. The risk of lactic acidosis is significantly increased in patients with congestive heart failure requiring pharmacologic management, particularly unstable or acute congestive heart failure with a risk of hypoperfusion and hypoxemia. The risk of lactic acidosis increases with the degree of renal impairment and the patient’s age; therefore, regular monitoring of renal function in patients taking Metformin and the use of the minimum effective dose of metformin significantly help reduce the risk of lactic acidosis. In particular, careful monitoring of renal function is necessary when treating elderly patients, and metformin therapy should not be initiated in patients 80 years of age or older unless measurement of creatinine clearance demonstrates that renal function is not reduced, as these patients are more susceptible to developing lactic acidosis. Furthermore, metformin should be promptly withheld in the presence of any condition associated with hypoxemia, dehydration, or sepsis. Since impaired hepatic function may significantly limit the ability to clear lactate, metformin should generally be avoided in patients with clinical or laboratory evidence of hepatic disease. Patients should be warned against excessive alcohol intake, acute or chronic, while taking metformin, since alcohol potentiates the effects of metformin on lactate metabolism. Additionally, metformin therapy should be temporarily discontinued for any surgical procedures and for radiographic studies involving the intravascular administration of iodinated contrast materials.

The onset of lactic acidosis is often subtle and accompanied only by nonspecific symptoms such as malaise, myalgia, respiratory distress, increasing somnolence, and nonspecific abdominal distress. More severe acidosis may be associated with hypothermia, hypotension, and resistant bradyarrhythmias. The patient and the physician should be aware of the possible significance of such symptoms and the patient should be instructed to notify the physician immediately if they occur. Metformin should be withdrawn until the situation is clarified. Measurement of blood lactate levels, plasma electrolytes, ketones, blood glucose, and, if indicated, blood pH, lactate levels, and blood metformin levels may be helpful. Gastrointestinal symptoms, which are common during initial therapy, are unlikely to be drug-related later during therapy when the patient is stable on a specific dose. The later occurrence of gastrointestinal symptoms could be due to lactic acidosis or other serious disease.

Elevated blood lactate levels (>upper limit of normal but ≤5 mmol/L) in the absence of acidosis are not necessarily a contraindication to metformin use. Such levels may be due to other mechanisms, such as poorly controlled diabetes or obesity, vigorous physical activity, or technical errors in sample handling.

Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis lacking evidence of ketoacidosis (ketonuria and ketonemia). Lactic acidosis is a medical emergency that must be treated in a hospital setting. In a patient with lactic acidosis who is taking Metformin, the drug should be discontinued immediately and general supportive measures promptly instituted. Because metformin is dialyzable (with a clearance of up to 170 mL/min under good hemodynamic conditions), hemodialysis is recommended to correct the acidosis and remove the accumulated metformin. These measures often result in prompt reversal of symptoms and recovery.

Hypoglycemia

Hypoglycemia does not occur in patients receiving metformin alone under usual circumstances of use, but could occur when caloric intake is deficient, when strenuous exercise is not compensated by caloric supplementation, or during concomitant use with other glucose-lowering agents (such as sulfonylureas and insulin) or ethanol. Elderly, debilitated, or malnourished patients, and those with adrenal or pituitary insufficiency or alcohol intoxication are particularly susceptible to hypoglycemic effects. Hypoglycemia may be difficult to recognize in the elderly and in people who are taking beta-adrenergic blocking drugs.

Concomitant Therapy

Concomitant pharmacologic therapy that may lead to significant hemodynamic changes or affect renal function and the distribution of metformin, such as cationic drugs that are eliminated by renal tubular secretion, should be used with caution.

Radiologic Studies with Intravascular Iodinated Contrast Materials (e.g., intravenous urogram, intravenous cholangiography, angiography, CT scans with intravascular contrast)

Intravascular administration of iodinated contrast materials can lead to acute renal failure and has been associated with lactic acidosis in patients taking Metformin. Therefore, in patients scheduled for such a procedure, the drug should be temporarily discontinued at least 48 hours prior to and for 48 hours following the procedure. Therapy may be restarted only after renal function has been re-evaluated and found to be normal.

Hypoxic States

Cardiovascular collapse (shock) from any cause, acute congestive heart failure, acute myocardial infarction, and other conditions characterized by hypoxemia have been associated with lactic acidosis and may also cause prerenal azotemia. If such events occur in a patient taking the Metformin+Sitagliptin combination, the drug should be promptly discontinued.

Surgical Procedures

The use of the drug should be temporarily discontinued for any surgical procedure (except minor procedures not associated with restricted intake of food and fluids) and should not be restarted until the patient’s oral intake has resumed and renal function has been evaluated as normal.

Alcohol Intake

Alcohol potentiates the effects of metformin on lactate metabolism. Patients should be warned against the hazard of acute or chronic excessive alcohol intake while receiving the drug.

Impaired Hepatic Function

Since impaired hepatic function has been associated with some cases of lactic acidosis, the drug should generally be avoided in patients with clinical or laboratory evidence of hepatic disease.

Plasma Cyanocobalamin (Vitamin B₁₂) Concentrations

In controlled clinical trials of metformin of 29 weeks’ duration, a decrease to subnormal levels of previously normal serum vitamin B₁₂ levels, without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B₁₂ absorption from the B₁₂-intrinsic factor complex, is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or vitamin B₁₂ supplementation. It is advisable to have hematological parameters checked annually while on therapy with the drug, and any apparent abnormalities should be appropriately investigated and managed. In patients with a predisposition to vitamin B₁₂ deficiency (due to reduced intake or absorption of vitamin B₁₂ or calcium), plasma vitamin B₁₂ levels should be assessed at 2- to 3-year intervals.

Change in Clinical Status in Patients with Previously Well-Controlled Type 2 Diabetes Mellitus

If laboratory abnormalities or clinical symptoms of a disease (especially any condition that cannot be clearly identified) appear in a patient with previously well-controlled type 2 diabetes mellitus while on therapy with the drug, it is necessary to immediately verify the absence of signs of ketoacidosis or lactic acidosis. The patient’s assessment should include blood plasma tests for electrolytes and ketones, blood glucose concentration, and (if indicated) blood pH value, lactate, pyruvate, and metformin concentrations. If acidosis of any etiology develops, administration of the drug should be stopped immediately and appropriate measures to correct the acidosis should be taken.

Deterioration of Glycemic Control

In situations of physiological stress (hyperthermia, trauma, infection, or surgical intervention), a patient with previously satisfactory glycemic control may experience a temporary loss of glycemic control. During such periods, temporary replacement of the drug with insulin therapy is acceptable, and after the acute situation resolves, the patient may resume previous treatment.

Effect on Ability to Drive and Operate Machinery

No studies have been conducted on the effect of the drug on the ability to drive vehicles and operate machinery. Nevertheless, cases of dizziness and drowsiness reported during the use of sitagliptin should be taken into account. In addition, patients should be aware of the risk of hypoglycemia when using the drug concomitantly with sulfonylurea derivatives or insulin.

Drug Interactions

Concomitant multiple administration of metformin (1000 mg twice daily) and sitagliptin (50 mg twice daily) in patients with type 2 diabetes mellitus was not accompanied by significant changes in the pharmacokinetic parameters of sitagliptin or metformin.

Studies on the effect of drug-drug interaction on the pharmacokinetic parameters of the drug have not been conducted, but there is a sufficient number of such studies for each of the drug’s components.

Sitagliptin

According to a drug interaction study, Sitagliptin did not have a clinically significant effect on the pharmacokinetics of the following drugs: metformin, rosiglitazone, glibenclamide, simvastatin, warfarin, oral contraceptives. Based on these data, it can be assumed that Sitagliptin does not inhibit the cytochrome P450 isoenzymes CYP3A4, 2C8, or 2C9. In vitro data indicate that Sitagliptin also does not suppress the CYP2D6, 1A2, 2C19, or 2B6 isoenzymes and does not induce the CYP3A4 isoenzyme.

According to a population pharmacokinetic analysis in patients with type 2 diabetes mellitus, concomitant therapy did not have a clinically significant effect on the pharmacokinetics of sitagliptin. The study evaluated a number of drugs most commonly used by patients with type 2 diabetes mellitus, including lipid-lowering drugs (e.g., statins, fibrates, ezetimibe), antiplatelet agents (e.g., clopidogrel), antihypertensive drugs (e.g., ACE inhibitors, angiotensin II receptor antagonists, beta-blockers, calcium channel blockers, hydrochlorothiazide), analgesics and NSAIDs (e.g., naproxen, diclofenac, celecoxib), antidepressants (e.g., bupropion, fluoxetine, sertraline), antihistamines (e.g., cetirizine), proton pump inhibitors (e.g., omeprazole, lansoprazole), and drugs for the treatment of erectile dysfunction (e.g., sildenafil).

A slight increase in the AUC value (by 11%), as well as the mean C_max value (by 18%) of digoxin was observed when co-administered with sitagliptin. This increase was not considered clinically significant. Monitoring of the patient is recommended when digoxin and sitagliptin are used concomitantly.

An increase in the AUC and C_max values of sitagliptin by approximately 29% and 68%, respectively, was observed with the concomitant single oral administration of sitagliptin 100 mg and cyclosporine (a strong P-glycoprotein inhibitor) 600 mg. These changes in the pharmacokinetic parameters of sitagliptin were not considered clinically significant.

Metformin

In a single-dose drug interaction study of metformin and glibenclamide in patients with type 2 diabetes mellitus, no changes in the pharmacokinetic and pharmacodynamic parameters of metformin were observed. The decrease in glibenclamide AUC and C_max values was highly variable.

Insufficient information (single dose) and the discrepancy between blood glibenclamide concentration and the observed pharmacodynamic effects call into question the clinical significance of this interaction.

In a drug interaction study with single doses of metformin and furosemide in healthy volunteers, changes in the pharmacokinetic parameters of both drugs were observed. Furosemide increased the C_max of metformin in plasma and whole blood by 22%, and the AUC of metformin in whole blood by 15% without a significant change in the renal clearance of metformin. When metformin and furosemide were taken concomitantly, the C_max and AUC of furosemide decreased by 31% and 12%, respectively, compared to taking furosemide alone, and T_1/2 decreased by 32% without a significant change in the renal clearance of furosemide. There is no information on the drug interaction between metformin and furosemide with long-term concomitant use.

A drug interaction study of nifedipine and metformin with single doses in healthy volunteers revealed an increase in the C_max and AUC of metformin in plasma by 20% and 9%, respectively, as well as an increase in the amount of metformin excreted by the kidneys. The T_max and T_1/2 of metformin did not change. Nifedipine increases the absorption of metformin. The effect of metformin on the pharmacokinetics of nifedipine is minimal.

Cationic drugs that are excreted by tubular secretion (e.g., amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, or vancomycin) could theoretically interact with metformin, as they are eliminated through a common renal tubular transport system. Such an interaction between metformin and cimetidine was observed during the concomitant oral administration of metformin and cimetidine in healthy volunteers in single-dose and multiple-dose interaction studies, in which the C_max and AUC of metformin in plasma and whole blood increased by 60% and 40%, respectively. In the single-dose study, the T_1/2 of metformin did not change. Metformin did not affect the pharmacokinetics of cimetidine. And although the indicated drug interaction is of theoretical significance (with the exception of cimetidine), careful monitoring of the patient and dose adjustment of the drug and/or the above-mentioned cationic drugs excreted by the proximal renal tubules is recommended in cases of their concomitant use.

Others Some drugs have hyperglycemic potential and may reduce glycemic control. These include thiazide and other diuretics, corticosteroids, phenothiazines, thyroid preparations, estrogens, oral contraceptive drugs, phenytoin, nicotinic acid, sympathomimetics, calcium channel blockers, and isoniazid. When prescribing the listed drugs to a patient receiving the combination Metformin + Sitagliptin, careful monitoring of glycemic control parameters is recommended.

In interaction studies involving healthy volunteers, no changes in the pharmacokinetic parameters of these drugs were observed with the concomitant administration of single doses of metformin and propranolol or metformin and ibuprofen.

Metformin is slightly bound to plasma proteins, so a drug interaction of metformin with drugs that are highly bound to plasma proteins (salicylates, sulfonamides, chloramphenicol, and probenecid) is unlikely compared to sulfonylurea derivatives, which are also highly bound to plasma proteins.

Storage Conditions

Store at 2°C (36°F) to 25°C (77°F). Keep in original packaging, protected from light. Keep out of reach of children.

Dispensing Status

Rx Only

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.