Prazosin
Prazosin: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacodynamics and pharmacokinetics
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Overdose
- 7. Side effects
- 8. Special instructions
- 9. Application during pregnancy and lactation
- 10. Use in childhood
- 11. Drug interactions
- 12. Analogs
- 13. Terms and conditions of storage
- 14. Terms of dispensing from pharmacies
- 15. Reviews
- 16. Price in pharmacies
Latin name: Prazosin
ATX code: C02CA01
Active ingredient: Prazosin (Prazosin)
Manufacturer: Norton Healthcare (UK)
Description and photo update: 02.10.2019
Prazosin is a selective blocker of postsynaptic alpha 1 -adrenergic receptors, a drug with antihypertensive and vasodilating effects.
Release form and composition
It is produced in the form of tablets (30 pcs. In polypropylene bottles, 1 bottle in a cardboard box).
The active substance is prazosin, in 1 tablet - 0.5 or 1 mg.
Pharmacodynamics and pharmacokinetics
According to the instructions, Prazosin has the following effect on the body:
- blocking postsynaptic α1-adrenergic receptors;
- decrease in the vasoconstrictor effect of catecholamines;
- decrease in total peripheral vascular resistance and decrease in blood pressure;
- expansion of peripheral veins;
- reduction of afterload on the heart;
- decrease in pressure in the pulmonary circulation;
- improvement of intracardiac and systemic hemodynamics in chronic heart failure;
- a decrease in myocardial oxygen demand and an increase in stroke volume of blood during physical exertion;
- decrease in renal vascular resistance;
- a decrease in pressure and resistance in the urethra and a decrease in the severity of symptoms of dysfunction of the urinary tract.
Taking the drug may be accompanied by the development of moderate reflex tachycardia. With prolonged use, a decrease in the concentration of atherogenic lipids in the blood is observed.
After taking a single dose, the maximum hypotensive effect develops in 1-4 hours. The duration of the drug is up to 10 hours. During treatment, early (after 3-5 days) or late (by 12 months) tolerance may develop, so the doctor may decide to increase the dose.
The drug is rapidly absorbed from the gastrointestinal tract (food intake does not affect absorption). The maximum concentration in the blood is reached within 1–3 hours. Bioavailability of Prazosin is from 50 to 85%, binding to plasma proteins exceeds 95%. The drug is metabolized in the liver.
The half-life of Prazosin is 2 to 4 hours. The drug is excreted mainly in the bile. In patients with chronic renal failure and elderly patients, the elimination half-life is prolonged.
Indications for use
- Arterial hypertension;
- Congestive heart failure.
Contraindications
Absolute:
- Heart disease with reduced left ventricular filling pressure;
- Constrictive pericarditis;
- Hypotension;
- Cardiac tamponade;
- Children under 12 years of age;
- Pregnancy and lactation period;
- Hypersensitivity to the drug.
Instructions for the use of Prazosin: method and dosage
The tablets should be taken orally. Food intake does not affect the effectiveness of the drug.
At the beginning of the treatment of arterial hypertension, 0.5 mg is prescribed at bedtime. Gradually, the dose is increased, first to 1 mg 3-4 times a day, and then until a persistent decrease in blood pressure is achieved (this usually takes 4 to 8 weeks). The optimal daily dose for each patient can vary within 3-20 mg, more often it is 6-15 mg. The total daily dose is divided into 3-4 doses.
When prescribing Prazosin as a monopreparation, it is necessary to take into account the possibility of developing tolerance. It is possible at the beginning of treatment (3-5 days) or after a few months. This phenomenon requires an increase in the dose of prazosin or additional prescription of diuretics.
With a slowly developing or insufficient hypotensive effect, other antihypertensive drugs or diuretics are additionally prescribed. In this case, the dose of Prazosin is reduced to 1-2 mg 3 times a day, a second drug is added, and then the dose is gradually increased again, choosing the most appropriate therapy regimen.
The duration of the drug is not limited.
With congestive heart failure, it is prescribed at 3-20 mg / day in 3-4 doses.
The maximum allowable daily intake for adults is 20 mg.
Overdose
Taking very high doses of the drug can cause a marked decrease in blood pressure. In such cases, it is recommended to take a horizontal position and raise your legs.
Side effects
- From the side of the central and peripheral nervous system: headache, weakness, vertigo, sleep disorders, emotional disorders, hallucinations, anxiety, impaired perception, depression, fatigue, paresthesia;
- From the side of the cardiovascular system: anginal pain, shortness of breath, tachycardia, palpitations, arterial hypotension (especially orthostatic); with prolonged use - edema of the lower extremities; rarely - orthostatic collapse (more often after taking the first dose);
- From the urinary system: frequent urination;
- From the digestive system: diarrhea or constipation, nausea, vomiting, dry mouth;
- From the senses: visual impairment, darkening of the eyes, redness of the cornea and conjunctiva, tinnitus;
- Allergic reactions: skin rash, itching;
- Others: hyperthermia, nasal congestion, hyperhidrosis, arthralgia, nosebleeds, the appearance of antinuclear factors, alopecia, decreased potency, priapism.
special instructions
During treatment, it is necessary to constantly monitor the heart rate and blood pressure, both in the lying position and standing.
In patients receiving beta-blockers, sympatholytics and diuretics, the likelihood of hypotension is higher.
Application during pregnancy and lactation
It is forbidden to use the drug during this period.
Pediatric use
It is forbidden to use the drug in the treatment of children under 12 years of age.
Drug interactions
Prazosin is incompatible with nifedipine. Its action is enhanced by sympatholytics, diuretics, beta-blockers.
With the simultaneous use of beta-blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, the risk of severe arterial hypotension increases, especially after taking the first dose of prazosin.
The vasodilating effect of calcium channel blockers and alpha-blockers can be synergistic or additive. With the simultaneous use of prazosin with verapamil, the development of severe arterial hypotension is partly due to their pharmacokinetic interaction: the maximum concentration increases and the total concentration of prazosin increases.
Indomethacin may reduce the effect of prazosin.
Prazosin promotes a rapid and significant increase in the level of digoxin in the blood plasma, and can alter the antihypertensive effect of clonidine.
In patients receiving propranolol, after taking the first dose of prazosin, there is a risk of developing severe arterial hypertension.
Analogs
Analogs of Prazosin are: Pratsiol, Adversuten, Eurex, Minipress.
Terms and conditions of storage
Store at temperatures up to 25 ºС, protected from light, dry and out of reach of children.
The shelf life is 3 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews about Prazosin
Reviews of Prazosin are positive: it is successfully used not only for high blood pressure, but also for prostatic hyperplasia and pheochromocytoma.
The price of Prazosin in pharmacies
The drug is not available in most pharmacies, so the price of Prazosin is unknown.
Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
Information about the drug is generalized, provided for informational purposes only and does not replace the official instructions. Self-medication is hazardous to health!
