Terazosin (Tablets) Instructions for Use

ATC Code

G04CA03 (Terazosin)

Active Substance

Terazosin (Rec.INN registered by WHO)

Clinical-Pharmacological Group

Alpha₁-adrenergic blocker. Antihypertensive agent. Agent used for urination disorders in benign prostatic hyperplasia

Pharmacotherapeutic Group

Drugs used in urology; drugs for the treatment of benign prostatic hyperplasia; alpha-adrenergic blockers

Pharmacological Action

Selective blocker of postsynaptic α₁-adrenergic receptors. By blocking these receptors on resistive (arterial) vessels, it causes their dilation, a decrease in total peripheral vascular resistance, and a reduction in blood pressure. It reduces the afterload on the heart. It also causes a decrease in the tone of capacitive (venous) vessels, reducing the preload on the heart. Unlike non-selective blockers of α₁– and α₂-adrenergic receptors, it does not cause significant tachycardia.

Terazosin has a certain hypolipidemic effect: its use is associated with a decrease in the levels of cholesterol, LDL, and VLDL (the mechanism of these effects is not clear). Furthermore, Terazosin normalizes urination in patients with benign hypertrophy (adenoma) of the prostate gland because, by blocking postsynaptic α₁-adrenergic receptors of the smooth muscles of the trigone and neck of the bladder, the proximal part of the urethra, and the prostate gland, it reduces resistance to urine flow.

Pharmacokinetics

After oral administration, it is rapidly and sufficiently completely absorbed from the intestine (80-100%). Absorption does not depend on food intake; bioavailability is more than 90%. C_max is reached within 1 hour. Plasma protein binding is 90-94%. It is metabolized in the liver to form 4 metabolites, one of which (a piperazine derivative of terazosin) has antihypertensive activity.

T_1/2 is 12 hours. It is excreted mainly through the intestine (60%, of which 20% is unchanged) and by the kidneys (40%, of which 10% is unchanged). In hepatic insufficiency, clearance is reduced.

Indications

Symptomatic treatment of benign prostatic hyperplasia (BPH). Treatment of arterial hypertension (as part of combination therapy).

ICD codes

Dosage Regimen

Determine the dosage individually based on indication, clinical situation, therapeutic efficacy, and patient tolerance.

For arterial hypertension, use Terazosin only as part of combination therapy with other antihypertensive agents.

For benign prostatic hyperplasia, use as monotherapy.

Initiate therapy with a 1 mg dose once daily at bedtime.

Increase the dose gradually to achieve the desired therapeutic effect. Titrate the dose upwards, typically doubling it, at intervals of no less than one week.

The usual maintenance dose for both hypertension and BPH is 2 mg to 10 mg administered once daily.

Do not exceed a maximum daily dose of 20 mg.

If therapy is interrupted for several days or longer, re-initiate treatment using the initial dosing regimen, starting with 1 mg at bedtime.

In elderly patients and patients with renal or hepatic impairment, exercise caution during dose titration due to an increased risk of hypotension.

Adverse Reactions

Infections and infestations Common – sinusitis; Frequency unknown – upper respiratory tract infections, bronchitis, pharyngitis, rhinitis, urinary tract infections.

Blood and lymphatic system disorders Frequency unknown – thrombocytopenia.

Immune system disorders Very rare – anaphylactic reactions.

Metabolism and nutrition disorders Rare – increased body weight; Frequency unknown – exacerbation of gout.

Psychiatric disorders Common – asthenia, increased irritability; Uncommon – depression; Frequency unknown – anxiety.

Nervous system disorders Common – dizziness, weakness, headache, drowsiness, paresthesia; Frequency unknown – insomnia.

Eye disorders Common – blurred vision, impaired color vision; Frequency unknown – conjunctivitis.

Ear and labyrinth disorders Very common – vertigo; Frequency unknown – tinnitus.

Cardiac disorders: Common – palpitations, tachycardia, chest pain, syncope (especially with rapid transition from a ‘lying’ to a ‘standing’ or ‘sitting’ position – postural hypotension), peripheral edema; Frequency unknown – vasodilation, orthostatic hypotension, atrial fibrillation (a causal relationship with terazosin intake has not been established), cardiac arrhythmia. After the first dose of terazosin, orthostatic hypotension up to fainting may occur; in isolated cases, heart rate may sharply increase to 120-160 beats/min before fainting.

Respiratory, thoracic and mediastinal disorders Common – dyspnea, nasal congestion; Frequency unknown – cough, epistaxis.

Gastrointestinal disorders: Common – nausea; Frequency unknown – abdominal pain, constipation, diarrhea, vomiting, dyspepsia, dry mouth, flatulence.

Skin and subcutaneous tissue disorders Frequency unknown – hyperhidrosis, skin rash and pruritus, urticaria.

Musculoskeletal and connective tissue disorders: Common – pain in extremity, back pain; Frequency unknown – arthralgia, arthritis, arthropathy, arthralgia, neck pain, shoulder pain.

Renal and urinary disorders: Frequency unknown – urinary tract infections, urinary incontinence (mainly in postmenopausal women), increased urinary frequency.

Reproductive system and breast disorders: Common – erectile dysfunction; Uncommon – decreased libido; Frequency unknown – priapism.

General disorders and administration site conditions Very common – asthenia; Common – increased fatigue, peripheral edema, mucosal edema; Frequency unknown – facial edema, hyperthermia, chest pain, flu-like syndrome, pyrexia, hemodilution phenomena.

Contraindications

Hypersensitivity to terazosin and other quinazolines and alpha-adrenergic blockers; simultaneous use with phosphodiesterase 5 (PDE5) inhibitors, such as sildenafil, tadalafil, and vardenafil; concomitant obstruction of the upper urinary tract; chronic infectious diseases of the urinary tract or bladder stones; arterial hypotension; predisposition to orthostatic regulation disorders, including in the medical history; severe hepatic impairment; severe renal impairment; decreased urine flow rate; anuria; history of syncope during urination; pregnancy, breastfeeding period; children and adolescents under 18 years of age.

With caution in cardiovascular system diseases: pulmonary edema with aortic or mitral stenosis, heart failure (HF) with high cardiac output, right ventricular failure due to pulmonary embolism or exudative pericarditis, left ventricular HF with low ventricular filling pressure, arterial hypotension; mild to moderate hepatic impairment, mild to moderate renal impairment, cerebrovascular disorders; elderly age (over 65 years); coronary artery disease, hypertensive retinopathy grade III or IV, type 1 diabetes mellitus, simultaneous use of terazosin with thiazide diuretics or other antihypertensive agents; dehydration, reduced salt intake (e.g., following a salt-free diet), water-electrolyte balance disorders.

Use in Pregnancy and Lactation

Terazosin is contraindicated for use during pregnancy. If use is necessary during lactation, the issue of discontinuing breastfeeding should be considered.

Use in Hepatic Impairment

Contraindicated in severe hepatic impairment. Should be used with caution in mild to moderate hepatic impairment. The daily dose of terazosin should be selected with caution.

Use in Renal Impairment

Contraindicated in severe renal impairment. Should be used with caution in mild to moderate renal impairment. Selection of the maintenance dose of terazosin in elderly patients, especially in patients with BPH over 65 years of age, is recommended to be done with caution, under medical supervision, due to the high risk of orthostatic hypotension in this patient group.

Pediatric Use

Contraindicated for use in children and adolescents under 18 years of age (efficacy and safety have not been established).

Geriatric Use

Should be prescribed with caution to elderly patients (over 65 years). Dose adjustment of terazosin is not required, but constant monitoring of the patient’s condition is necessary.

Special Precautions

Before starting therapy for benign prostatic hyperplasia (BPH), a malignant neoplasm of the prostate gland should be ruled out. When prescribing the drug to patients with BPH, blood pressure should be monitored at the beginning of treatment and when changing the dose during therapy.

Regardless of the indications for which Terazosin is prescribed, to avoid the development of the “first-dose effect”, the initial dose of terazosin should not exceed 1 mg. Blood pressure must be carefully monitored to reduce the risk of orthostatic arterial hypotension.

To reduce the risk of orthostatic arterial hypotension (“first-dose effect”), the first dose of terazosin is recommended to be taken in the evening before bedtime, after which the patient should remain in bed for 6-8 hours. The risk of a pronounced decrease in blood pressure is highest within 30-90 minutes after administration, and is also increased in patients simultaneously receiving beta-blockers and diuretics, with reduced blood volume, when following a low-salt diet, and when resuming treatment with terazosin after a break (several days).

The patient should be informed that at the first signs of orthostatic hypotension (dizziness, weakness), the patient should sit or lie down and remain in this position until feeling better, as well as about the increased risk of a pronounced decrease in blood pressure when consuming alcohol, prolonged standing or exercising, and in high ambient temperatures.

Caution should be exercised with the simultaneous use of terazosin with thiazide diuretics or other antihypertensive agents; if combination therapy is necessary, the dose of terazosin should be reduced. Simultaneous use of PDE-5 inhibitors, including sildenafil, tadalafil, vardenafil, may lead to a pronounced decrease in blood pressure.

In some patients previously taking tamsulosin, “intraoperative floppy iris syndrome” (a variant of small pupil syndrome) was noted during cataract surgery.

When performing cataract surgery, the ophthalmic surgeon must be informed about the use of α₁-adrenergic receptor blockers.

During treatment of BPH with terazosin, the PSA concentration does not change.

Effect on ability to drive vehicles and operate machinery

During the use of terazosin, patients should exercise caution when driving vehicles and operating machinery, as well as when engaging in other potentially hazardous activities that require increased concentration and speed of psychomotor reactions.

Drug Interactions

With simultaneous use of terazosin with other antihypertensive agents, an enhancement of the antihypertensive effect is possible.

With simultaneous use with thiazide diuretics or other antihypertensive agents, a reduction in the dose of terazosin or even its discontinuation may be required, followed by re-titration of the terazosin dose under medical supervision.

Simultaneous use of terazosin with other alpha-adrenergic blockers is not recommended due to an increased frequency of adverse reactions.

With simultaneous use with vasodilators and nitrates, the antihypertensive effect of terazosin may be enhanced.

Simultaneous use of terazosin and PDE-5 inhibitors (such as sildenafil, tadalafil, vardenafil) may cause a pronounced decrease in blood pressure.

With simultaneous use with terazosin, NSAIDs (especially indomethacin) and estrogens may reduce the antihypertensive effect of terazosin, due to suppression of prostaglandin synthesis and/or retention of fluid and sodium.

With simultaneous use, Terazosin may weaken the peripheral vasoconstrictor effect of dopamine, epinephrine, norepinephrine, metaraminol, methoxamine, and phenylephrine. Sympathomimetics may weaken the antihypertensive effect of terazosin.

With simultaneous use, Terazosin reduces the antihypertensive effect of clonidine administered intravenously.

Absorption of terazosin is reduced with simultaneous intake of adsorbents and antacids.

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.