Doxazosin
Doxazosin: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacological properties
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Side effects
- 7. Overdose
- 8. Special instructions
- 9. Application during pregnancy and lactation
- 10. Use in childhood
- 11. In case of impaired renal function
- 12. For violations of liver function
- 13. Use in the elderly
- 14. Drug interactions
- 15. Analogs
- 16. Terms and conditions of storage
- 17. Terms of dispensing from pharmacies
- 18. Reviews
- 19. Price in pharmacies
Latin name: Doxazosin
ATX code: C02CA04
Active ingredient: doxazosin (doxazosin)
Manufacturer: Nu-Pharm Inc. (Canada), Skopinsky pharmaceutical plant (Russia), Obolenskoe - pharmaceutical company (Russia), ZiO-Zdorov'e (Russia), NIOPIK SSC (Russia)
Description and photo update: 2019-14-08
Prices in pharmacies: from 94 rubles.
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Doxazosin is a drug with hypolipidemic, hypotensive, antispasmodic and vasodilating effects.
Release form and composition
Doxazosin is produced in the form of tablets: from white with a grayish-cream shade to white (7, 10, 14, 20, 25, 30, 50 pcs. In blisters, 1-5 packs in a cardboard box; 10, 14, 20, 28, 30, 50, 100 pcs. In cans or bottles, 1 can or bottle in a cardboard box).
The composition of 1 tablet includes:
- Active ingredient: doxazosin - 1, 2 or 4 mg (in the form of mesylate);
- Auxiliary components: milk sugar, sodium glycolate, starch, magnesium stearic acid, microcrystalline cellulose, sodium lauryl sulfate.
Pharmacological properties
Pharmacodynamics
In benign prostatic hyperplasia (BPH), doxazosin significantly improves urodynamic parameters and reduces symptoms of the disease. This effect is due to the selective blockade of α-adrenergic receptors in the capsule and stroma of the prostate gland, as well as in the bladder neck.
Doxazosin blocks α 1 -adrenergic receptors of subtype 1A, which constitute about 70% of the total number of α 1 -adrenergic receptors of all subtypes located in the prostate gland. The action of the drug in BPH is based on this mechanism.
The safety and supportive effect of doxazosin treatment has been proven during long-term use of the drug (for example, up to 48 months).
When using doxazosin in patients with arterial hypertension, a decrease in the total peripheral vascular resistance is noted, which leads to a significant decrease in blood pressure. This effect is the result of a selective blockade of alpha1-adrenergic receptors in the vascular network.
When taken once a day, the drug provides a clinically significant antihypertensive effect for 24 hours. The decrease in blood pressure occurs gradually. After oral administration, the maximum effect is usually achieved after 2-6 hours. In arterial hypertension, the effect of doxazosin treatment was the same in the standing and lying positions.
It is noted that long-term treatment with doxazosin did not develop tolerance to the drug, in contrast to therapy with non-selective alpha1-blockers. During maintenance therapy, tachycardia and an increase in plasma renin activity are uncommon.
Doxazosin therapy has a beneficial effect on the lipid profile of the blood, since in this case the ratio of high density lipoproteins to total cholesterol increases, and the concentration of total cholesterol and total triglycerides is significantly reduced. Treatment with the drug has an advantage over the use of beta-blockers and diuretics, which do not have a beneficial effect on these parameters.
Taking into account the established relationship between the lipid profile of blood, arterial hypertension and coronary heart disease, normalization of blood pressure and lipid concentration that occurs when taking doxazosin helps to reduce the likelihood of coronary heart disease.
It was found that, as a result of doxazosin therapy, regression of left ventricular hypertrophy was observed, platelet aggregation was suppressed, and the activity of tissue plasminogen activator increased. Research has also shown that in patients with impaired glucose tolerance, doxazosin increases insulin sensitivity.
Doxazosin has no metabolic side effects and can be prescribed to patients with bronchial asthma, left ventricular failure, gout and diabetes mellitus.
In vitro, the antioxidant properties of 7 'and 6'-hydroxymetabolites of doxazosin are manifested at a concentration of 5 μmol.
In controlled clinical trials in patients with hypertension, doxazosin therapy was accompanied by an improvement in erectile function. Along with this, in patients who received doxazosin, subsequent erectile dysfunction occurred less frequently than in patients who received antihypertensive drugs.
Pharmacokinetics
After oral administration of therapeutic doses of Doxazosin, the active substance is well absorbed (from 80 to 90%). Its concentration in the blood reaches a maximum after about 2 hours.
The connection with blood plasma proteins is approximately 98%.
Doxazosin is actively biotransformed in the liver. Its metabolites have no pharmacological activity. Bioavailability is about 69-70% (first pass effect). The primary pathways of doxazosin metabolism are hydroxylation and O-demethylation.
The drug is characterized by two-phase elimination from blood plasma. The half-life is 22 hours, which allows prescribing the drug once a day. When taken orally, most of doxazosin is excreted through the intestine in the form of inactive metabolites, and in unchanged form - up to 5% of the dose taken.
Data from pharmacokinetic studies of the effect of the drug in elderly patients and in patients with renal insufficiency show that the pharmacokinetics of doxazosin does not differ significantly from that in younger patients with normal renal function.
There are only limited data on pharmacokinetics in patients with impaired liver function, as well as on the effect of drugs that can alter hepatic metabolism (for example, cimetidine). In a clinical study, a single dose of doxazosin in 12 patients with moderate hepatic dysfunction was accompanied by a 43% increase in the AUC (area under the concentration-time curve) and a 40% decrease in true oral clearance.
Indications for use
- Arterial hypertension (as monotherapy or simultaneously with other antihypertensive drugs: beta-blockers, thiazide diuretics, angiotensin-converting enzyme inhibitors or calcium channel blockers);
- Benign prostatic hyperplasia (with normal blood pressure and in the presence of arterial hypertension).
Contraindications
- Age under 18;
- Pregnancy and lactation;
- Hypersensitivity to drug components.
According to the instructions, Doxazosin should be taken with caution in the following diseases / conditions:
- Pulmonary edema due to mitral or aortic stenosis;
- Left ventricular failure with low filling pressure;
- Insufficiency of the right ventricle of the heart, due to effusion into the pericardial cavity or pulmonary embolism;
- Insufficient cardiac output.
Particular care is required to prescribe the drug for functional disorders of the liver, when drugs that can have a negative effect on liver function are simultaneously used. If the indicators of the functional state of the liver deteriorate, Doxazosin should be canceled immediately.
Instructions for the use of Doxazosin: method and dosage
Doxazosin is taken orally, regardless of food intake. The tablets should be taken with plenty of water without chewing.
The drug is taken once a day (in the morning or evening). The daily dose is determined by the indications:
- Arterial hypertension: the dose can vary from 1 (initial) to 16 mg (maximum). It is recommended that the initial dose be taken at bedtime. After taking the drug, the patient should be in bed for 6-8 hours (due to the possible development of the "first dose" phenomenon, especially pronounced after the previous intake of diuretics). After 7-14 days of continuous treatment, in case of insufficient therapeutic effect, it is possible to increase the daily dose by 2 times. If necessary, after the same time interval, you can increase the dose by another 2 mg, and so on until the optimal therapeutic effect is achieved. In the future, after achieving a stable therapeutic effect, the daily dose is usually reduced (with maintenance therapy, the average therapeutic daily dose is 2-4 mg);
- Benign prostatic hyperplasia without arterial hypertension: 2-4 (usually) to 8 mg (maximum) per day.
Side effects
During therapy, especially at the beginning, orthostatic hypotension most often develops, which in some cases can lead to fainting. To prevent this disorder, it is recommended to avoid abrupt and unexpected changes in body position (transition to a standing position from a prone position).
In addition, when taking Doxazosin, you may experience: nausea, dizziness, headache, a general feeling of weakness, drowsiness, fatigue and rhinitis. Patients with arterial hypertension can sometimes experience: arrhythmia, tachycardia, chest pain, myocardial infarction, angina attacks, cerebrovascular disorders.
There have also been isolated cases of allergic reactions (jaundice, skin rash, increased transaminase levels, thrombocytopenic purpura), nosebleeds, dry mouth, priapism, urinary incontinence, constipation, increased appetite, increased urine output, arthralgia and myalgia.
Overdose
Symptoms: dizziness, headache, shortness of breath, nausea, vomiting, loss of consciousness, a marked decrease in blood pressure, sometimes with concomitant fainting, tachycardia, palpitations, arrhythmia, hypokalemia, hypoglycemia.
Treatment: symptomatic therapy. Blood pressure monitoring is shown. Dialysis is ineffective, since the binding of the active substance to blood plasma proteins is high.
special instructions
Alcohol increases unwanted reactions.
At the beginning of therapy or during an increase in the daily dose, it is advisable to refrain from performing all potentially hazardous types of work, in particular, from driving and driving other vehicles and mechanisms.
Application during pregnancy and lactation
In the course of experiments on animals, it has been proven that doxazosin does not have a teratogenic effect. At the same time, the use of extremely high doses of the substance led to a decrease in fetal survival. As a result, despite the absence of embryotoxic and teratogenic effects in the results of experimental studies, the drug can be prescribed to pregnant women only in cases where the potential benefit to the mother is higher than the potential risk to the fetus.
Studies in rats have shown that doxazosin accumulates in the milk of females.
It is not known whether this substance is excreted in human breast milk. If necessary, use of the drug during lactation should stop breastfeeding.
Pediatric use
It is forbidden to use Doxazosin to treat patients under the age of 18 years.
With impaired renal function
It is forbidden to use the drug in case of progressive renal failure.
For violations of liver function
It is forbidden to use Doxazosin for severe hepatic impairment. The drug should be used with caution in mild to moderate hepatic impairment.
Use in the elderly
When treating elderly patients, the drug should be used with caution.
Drug interactions
With the simultaneous use of Doxazosin with certain drugs, undesirable effects may occur:
- Antihypertensive drugs: increased hypotensive effect;
- Inducers of microsomal oxidation in the liver: the effect of doxazosin may increase;
- Inhibitors of microsomal oxidation in the liver: may decrease the effect of doxazosin;
- Non-steroidal anti-inflammatory drugs (especially indomethacin), sympathomimetic agents and estrogens: lowering the hypotensive effect;
- Ephedrine: lowering the pressor effect;
- Epinephrine: simultaneously with the elimination of alpha-adrenostimulating effects, it is possible to develop a perversion of its pressor action and tachycardia.
Doxazosin is compatible with furosemide, thiazide diuretics, calcium channel blockers, beta-blockers, angiotensin-converting enzyme inhibitors, oral hypoglycemic agents, antibiotics, uricosuric agents, and indirect anticoagulants.
Analogs
Doxazosin analogues are: Artezin, Doxazosin-FPO, Kamiren, Kamiren HL, Kardura, Prazosin, Omnik, Terazosin, Flosin.
Terms and conditions of storage
Store in a dark, dry place out of reach of children at a temperature of 5-25 ° C.
Shelf life is 2 years.
Terms of dispensing from pharmacies
Available without a prescription.
Reviews about Doxazosin
Reviews of Doxazosin from users with BPH indicate that when taking this drug, there is often an improvement in the condition, but complete recovery does not occur. Many men note that while taking pills and carrying out physiotherapy procedures, they get better, but after stopping therapy, the manifestations of the disease return.
The effectiveness of the use of Doxazosin in the treatment of arterial hypertension is evaluated by users in different ways. In such cases, the drug is often used as part of complex therapy.
In any case, users note that Doxazosin can only be used as directed by a specialist and under medical supervision.
Price for Doxazosin in pharmacies
The approximate price for Doxazosin is: 30 4 mg tablets - 280 rubles, 90 4 mg tablets - 810 rubles.
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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!
