Letizen (Tablets, Solution) Instructions for Use

ATC Code

R06AE07 (Cetirizine)

Active Substance

Cetirizine (Rec.INN registered by WHO)

Clinical-Pharmacological Group

Histamine H₁-receptor blocker. Antiallergic drug

Pharmacotherapeutic Group

H1 histamine receptor blocker

Pharmacological Action

Third-generation histamine H₁-receptor blocker. It affects the “early” stage of the allergic reaction and reduces eosinophil migration; limits the release of mediators at the “late” stage of the allergic reaction.

It has practically no anticholinergic or antiserotonin action. In therapeutic doses, it does not cause a sedative effect.

Pharmacokinetics

It is rapidly absorbed from the gastrointestinal tract. C_max after oral administration is reached within 1 hour. The bioavailability of cetirizine when taken as tablets and syrup is the same.

Food does not affect the completeness of absorption (AUC), but prolongs the time to reach C_max by 1 hour and reduces the value of C_max by 23%.

When taken at a dose of 10 mg once a day for 10 days, the C_ss in plasma is 310 ng/ml and is noted 0.5-1.5 hours after administration. Plasma protein binding is 93% and does not change at cetirizine concentrations in the range of 25-1000 ng/ml.

The pharmacokinetic parameters of cetirizine change linearly when prescribed in a dose of 5-60 mg. V_d is 0.5 l/kg. It is metabolized in small amounts in the liver by O-dealkylation to form a pharmacologically inactive metabolite (unlike other H₁-histamine receptor antagonists, which are metabolized in the liver by the cytochrome system).

It does not accumulate. Two-thirds of the dose is excreted unchanged by the kidneys and about 10% in the feces. Systemic clearance is 53 ml/min. T_1/2 in adults is 7-10 hours, in children aged 6 to 12 years – 6 hours, from 2 to 6 years – 5 hours, from 6 months to 2 years – 3.1 hours.

In elderly patients, T_1/2 increases by 50%, and systemic clearance decreases by 40% (decreased renal function). In patients with impaired renal function (creatinine clearance <40 ml/min), the clearance of the drug decreases, and T_1/2 is prolonged (for example, in patients on hemodialysis, total clearance decreases by 70% and is 0.3 ml/min/kg, and T_1/2 is prolonged 3 times), which requires an appropriate change in the dosage regimen.

It is practically not removed during hemodialysis. In patients with chronic liver diseases (hepatocellular, cholestatic or biliary cirrhosis), an increase in T_1/2 by 50% and a decrease in total clearance by 40% are noted (dose adjustment is required only with a concomitant decrease in the glomerular filtration rate). It penetrates into breast milk.

Indications

Hay fever; allergic rhinitis, conjunctivitis, dermatitis; urticaria, Quincke’s edema.

ICD codes

Dosage Regimen

Administer the tablet or solution orally, with or without food.

For adults and adolescents 12 years and older, the standard dose is 10 mg once daily.

For children aged 6 to 11 years, administer 5 mg (1/2 tablet or 5 ml solution) twice daily or 10 mg once daily.

For children aged 2 to 5 years, the recommended dose is 2.5 mg (1.25 ml solution) twice daily or 5 mg once daily.

For patients with moderate to severe renal impairment (creatinine clearance less than 30 ml/min) or on hemodialysis, reduce the dose by half.

Administer 5 mg once daily to renally impaired adults and adolescents.

For renally impaired children aged 6 to 11 years, administer 2.5 mg once daily.

For renally impaired children aged 2 to 5 years, administer 2.5 mg every other day.

In patients with hepatic impairment and normal renal function, no dose adjustment is required.

For elderly patients with normal renal function, use the standard adult dose.

Do not exceed the recommended daily dose.

Adverse Reactions

Possible dry mouth, drowsiness, headache, fatigue.

Rarely skin manifestations of allergic reactions, angioedema.

In some cases dyspepsia, agitation.

Contraindications

Renal failure, pregnancy, lactation period, hypersensitivity to cetirizine.

Use in Pregnancy and Lactation

Contraindicated for use during pregnancy and lactation.

Use in Renal Impairment

Contraindicated in renal failure.

Cetirizine should be prescribed with caution to patients with chronic renal failure (moderate and severe – dose adjustment is required).

Pediatric Use

Cetirizine should be prescribed with caution to children (experience of use in children under 1 year of age is insufficient).

Geriatric Use

Cetirizine should be prescribed with caution to elderly patients (a decrease in glomerular filtration rate is possible).

Elderly patients with normal renal function do not require dose adjustment.

Special Precautions

Cetirizine should be prescribed with caution to patients with chronic renal failure (moderate and severe – dose adjustment is required), and to elderly patients (a decrease in glomerular filtration rate is possible).

Elderly patients with normal renal function do not require dose adjustment.

Use in pediatrics

Cetirizine should be prescribed with caution to children (experience of use in children under 1 year of age is insufficient).

Effect on ability to drive vehicles and operate machinery

When the dose exceeds 10 mg/day, the ability for rapid reactions may deteriorate. During the treatment period, it is necessary to refrain from engaging in potentially hazardous activities that require increased concentration and speed of psychomotor reactions.

Drug Interactions

No pharmacokinetic interaction with pseudoephedrine, cimetidine, ketoconazole, erythromycin, azithromycin, diazepam and glipizide was found.

Concomitant administration with theophylline (400 mg/day) led to a 16% decrease in the total clearance of cetirizine (the kinetics of theophylline did not change).

Storage Conditions

Store at 2°C (36°F) to 30°C (86°F). Keep in original packaging, protected from light. Keep out of reach of children.

Dispensing Status

Over-the-Counter

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.