Doxazosin - instructions for use, dose, side effects, contraindications

Doxazosin is a selective competitive blocker of postsynaptic alpha 1-adrenergic receptors. By reducing the tone of the muscles of the vessels reduces the overall peripheral vascular resistance, which leads to a decrease in blood pressure (BP). After a single administration of the drug, a maximum of hypotensive action is observed in the period from 2 to 6 hours, and in general the hypotensive effect persists for 24 hours. In the period of treatment with doxazosin in patients with arterial hypertension there are no differences in the values of blood pressure in the standing and lying position.

Effective in hypertension, including those accompanied by metabolic disorders (obesity, decreased glucose tolerance).

Reduces the risk of coronary heart disease.

Admission of the drug in "normotonics" is not accompanied by a decrease in blood pressure.

With long-term use of doxazosin, patients do not exhibit changes in tolerance to the therapeutic antihypertensive effect.

During the period of treatment with the drug, the level of concentration in the blood plasma of triglycerides, total cholesterol, is reduced. At the same time, there is a certain (by 4% -13%) increase in the HDL / total cholesterol ratio.

With prolonged treatment with Doxazosin, regression of left ventricular hypertrophy, inhibition of platelet aggregation, and an increase in active plasminogen in tissues are observed.

Due to doxazosin blocks alpha1-adrenergic receptors located in the stroma and capsule of the prostate gland and in the neck of the bladder, the resistance and pressure in the urethra decrease, the resistance of the internal sphincter decreases. Therefore, the appointment of Doxazosin to patients with symptoms of benign prostatic hyperplasia leads to a significant improvement in urodynamics and a reduction in symptoms of the disease.

The effect in 66-71% of patients, the onset of action - after 1-2 weeks of treatment, maximum - after 14 weeks, the effect persists for a long time.

Pharmacokinetics:

After oral administration in therapeutic doses well absorbed, absorption - 80-90% (simultaneous intake of food slows down absorption by 1 hour). The maximum concentration in the blood plasma is created after 3 hours. At evening reception time of achievement of the maximum concentration is extended to 5 hours.

Bioavailability - 60-70% (presystemic metabolism). The connection with blood plasma proteins is about 98%. Excretion from the blood plasma occurs in 2 phases, with a finite half-life of -19-22 h, which allows you to prescribe the drug once a day.

Intensively metabolized in the liver by o-demethylation and hydroxylation.

In patients with impaired liver function, as well as when taking drugs that can alter hepatic metabolism, the biotransformation of the drug may be disrupted.

The main excretion through the intestine (65% in the form of metabolites and about 5% in unmodified form). The kidneys show 10%.

A study of the pharmacokinetics of doxazosin in elderly patients and in patients with kidney disease there were no significant pharmacokinetic differences.

Indications:

- Arterial hypertension: (in combination with other antihypertensive agents (thiazide diuretics, beta-adrenoblockers, blockers of "slow" calcium channels,inhibitors of angiotensin-converting enzyme (ACE)).

- Benign prostatic hyperplasia:

As in the presence of arterial hypertension, and with normal blood pressure.

Contraindications:- Hypersensitivity to doxazosin, other quinazolone derivatives or to any of the auxiliary components of the drug;

- under the age of 18 years (efficiency and safety not established).

Carefully:

Use with caution for violations of liver function, aortic and mitral stenosis, orthostatic hypotension.

Pregnancy and lactation:

To date, the experience of Doxazosin in patients with arterial hypertension during pregnancy and during breastfeeding is not enough. Therefore, despite the absence of teratogenic and embryogenic effects according to experimental studies, Doxazosin can be assigned at pregnancy and during lactation only after careful weighing by the attending physician benefit / risk ratio.

Safety and efficiency applications in childhood are not established.

Dosing and Administration:

Doxazosin is taken orally 1 time per day (morning or evening), regardless of food intake, without chewing and drinking with a sufficient amount of water.

In the treatment of hypertension the initial dose is 1 mg per day before bedtime. After taking the first dose, the patient should be in bed for 6-8 hours. This is required in connection with the possibility of developing a "first-dose phenomenon", especially pronounced against the background of previous intake of diuretics.

If the therapeutic effect is insufficient, the daily dose can be increased to 2 mg in 1-2 weeks. In the following, every 1-2 weeks the dose can be increased by 2 mg.

In the vast majority of patients, the optimal therapeutic effect is achieved at a dose of 8 mg per day. The maximum dose - 16 mg per day, can not be exceeded. After achieving a stable therapeutic effect, the dose is usually somewhat reduced (the average therapeutic dose with maintenance therapy is usually 2-4 mg per day).

In the treatment of patients with benign prostatic hyperplasia without arterial hypertension, doses equal to 2-4 mg per day are usually used. The maximum permissible is a dose equal to 8 mg per day.

A drug Doxazosin apply for a long time.

The duration of treatment is determined by the attending physician.

Side effects:

Arterial hypertension

In clinical trials, orthostatic hypotension was most often observed, especially at the beginning of treatment, which in rare cases can lead to fainting.

General reactions: asthenia, fatigue, malaise.

From the central nervous system: headache, dizziness, drowsiness.

From the gastrointestinal tract: nausea.

From the side of the cardiovascular system: swelling, fainting.

From the respiratory system: rhinitis.

Benign prostatic hyperplasia (BPH)

Patients with BPH have the same side effects as patients with hypertension, as well as:

General reactions: allergic reactions, skin rash, urticaria, back pain, sensation of heat ("hot flashes").

From the side of the cardiovascular system: decreased blood pressure, orthostatic hypotension.

From the central and peripheral nervous system: dry mouth, priapism, hyposthenia, parasthesia, tremor, impotence, insomnia, increased excitability.

From the endocrine system: gynecomastia.

From the gastrointestinal side tract: abdominal pain, constipation, diarrhea, dyspepsia, flatulence, nausea, loss of appetite.

From the hepatobiliary system: increased activity of "liver" transaminases, cholestasis, hepatitis, jaundice.

From the urinary system: dysuria, hematuria, urination disorder, nocturia, polyuria; rarely - urinary incontinence.

From the hemopoietic system and hemostasis system: thrombocytopenia, thrombocytopenic purpura, leukopenia;

From the respiratory system: bronchospasm, cough, shortness of breath, nosebleed.

From the skin: allopecia.

From the sense organs: blurred vision, tinnitus.

And also noted the following adverse reactions in patients arterial hypertension (cause-and-effect relationship not established): bradycardia, tachycardia, palpitation, chest pain, angina pectoris, myocardial infarction, cerebrovascular accident, arrhythmias.

Overdose:

Symptoms: marked decrease in blood pressure, sometimes accompanied by fainting.

Treatment: The patient should be immediately placed in a horizontal position, raise his legs.Symptomatic therapy is performed. Dialysis is ineffective.

Interaction:

Doxazosin enhances the antihypertensive effect of antihypertensive agents.

There was no adverse interaction with simultaneous use of doxazosin and thiazide diuretics, furosemide, beta adrenoblockers, slow calcium channel blockers, angiotensin converting enzyme inhibitors, antibiotics, oral hypoglycemic agents, indirect anticoagulants and uricosuric agents.

Does not affect the degree of absorption with blood plasma proteins digoxin, phenytoin.

When used simultaneously with inducers of microsomal oxidation in the liver, it is possible to increase the effectiveness of Doxazosin, with inhibitors a decrease.

Non-steroidal anti-inflammatory drugs (especially indomethocin), estrogens and sympathomimetic agents can reduce the hypotensive effect of doxazosin.

Eliminating alpha-adrenostimulating effects of epinephrine, can lead to tachycardia and arterial hypotension.

Special instructions:

Features of application for chronic diseases

Particular care should be exercised in the appointment of this drug to patients with impaired liver function, especially in cases where concurrent use of drugs that may adversely affect liver function. In cases of worsening of the functional state of the liver, the drug is immediately withdrawn.

In order to prevent orthostatic reactions, patients should avoid sudden and abrupt changes in body position (transition from lying to standing position).

Features of the drug at the first admission

The effect of the "first" administration of the drug is particularly pronounced against the background of previous diuretic therapy and a diet with sodium restriction. Before the beginning of therapy it is necessary to exclude the cancer degeneration of the prostate gland.

Effect on the ability to drive transp. cf. and fur:

Due to Doxazosin can cause orthostatic reactions at the beginning of treatment or during the period of increasing dosages, it is advisable for patients to refrain from all potentially hazardous activities, in particular from management motor transport and other vehicles and mechanisms. Taking alcohol can increase unwanted reactions.

Form release / dosage:Tablets, 2 mg.

Packaging:

For 10 tablets in a contour mesh box made of PVC film and aluminum foil printed lacquered.

For 2, 3, 5 or 9 contour packagings together with instructions for use.

Storage conditions:

In a dry, the dark place at a temperature of no higher than 25 ° C.

Keep out of the reach of children.

Shelf life:

3 years.

Do not use after the expiration date.

Terms of leave from pharmacies:On prescription

Registration number:P N003813 / 01

Date of registration:02.10.2009 / 03.04.2012

Expiration Date:Unlimited

The owner of the registration certificate:ZIO-HEALTH, JSC ZIO-HEALTH, JSC Russia

Manufacturer: & nbsp

ZIO-HEALTH, JSC Russia

Information update date: & nbsp21.11.2016

Illustrated instructions

Instructions

Doxazosin (Doxazosin)