Doxazosin

Brand Obolensky OP

In stock 1687 Items

Available since: 2019-09-19

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Clinical Pharmacology

Pharmaceutical group: alpha1-blocker

Pharmacodynamics: Doxazosin is a selective competitive blocker postsynaptic alpha1-adrenergic receptors (affinity for alpha1-adrenoceptors 600 times higher than for alpha2 adrenoceptors) decreases total peripheral vascular resistance (TPR), prevents vasoconstriction caused by catecholamines, which ultimately leads to lower blood pressure (BP) without developing reflex tachycardia.

Reduces pre-and afterload on the heart. After a single dose, a decrease in blood pressure develops gradually, the maximum decrease is observed after 2-6 hours and lasts for 24 hours.

After a single dose of the drug, the maximum of the hypotensive effect is observed in the period from 2 to 6 hours, and in general, the hypotensive effect lasts for 24 hours. In the period of treatment with doxazosin in patients with arterial hypertension (AH) there are no differences in the values of blood pressure in the "standing" and "lying" positions.

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

Reduces the risk of developing coronary heart disease (CHD). Taking the drug in patients with normal blood pressure is not accompanied by a decrease in blood pressure. With prolonged use of doxazosin, patients develop tolerance.

During treatment with doxazosin, a decrease in plasma concentration of triglycerides, total cholesterol, is observed. At the same time, there is some (by 4-13%) increase in the high-density lipoprotein ratio / total cholesterol.

With prolonged treatment with doxazosin, there is regression of left ventricular (LV) hypertrophy, suppression of platelet aggregation and an increase in the content of active plasminogen in the tissues.

Due to the fact that doxazosin blocks alpha1-adrenoreceptors located in the stroma and the capsule of the prostate gland and in the bladder neck, there is a decrease in resistance and pressure in the urethra, a decrease in resistance of the internal sphincter. Therefore, the administration of doxazosin to patients with symptoms of benign prostatic hyperplasia (BPH) leads to a significant improvement in urodynamic indicators and a decrease in symptoms of the disease.

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

Pharmacokinetics: After oral administration in therapeutic doses, doxazosin is well absorbed, absorption - 80-90% (simultaneous ingestion slows down the absorption for 1 hour), the time to reach the maximum plasma concentration (TC_max) is 3 hours, with evening reception of the vehicle_max lengthened to 5 hours.

Bioavailability - 60-70%. Communication with plasma proteins is about 98%. Removal from blood plasma occurs in 2 phases, with a final half-life (T_½) - 19-22 hours, which allows you to prescribe the drug 1 time per day.

Intensively metabolized in the liver by omethylation and hydroxylation. In patients with impaired liver function, as well as when taking drugs that can change the "liver" metabolism, the process of biotransformation of the drug may be disrupted. The main elimination is through the intestines (63-65% in the form of metabolites and about 5% in unchanged form). About 10% is excreted by the kidneys. A study of the pharmacokinetics of doxazosin in elderly patients and patients with kidney disease did not reveal significant pharmacokinetic differences.

Indications

· Benign prostatic hyperplasia: both in the presence of hypertension and in the normal level of arterial pressure.

· Arterial hypertension (as part of combination therapy).

Composition

1 tablet contains:

active substance:

Doxazosin Mesylate 1.22 mg / 2.44 mg / 4.88 mg (in terms of doxazosin

1 mg / 2 mg / 4 mg);

Excipients:

lactose monohydrate 80.18 mg /

90.16 mg / 180.32 mg; calcium phosphate 17.0 mg / 35.0 mg / 70.0 mg; Povidone K30 0.4 mg / 0.6 mg / 1.2 mg; sodium lauryl sulfate 0.2 mg / 0.3 mg / 0.6 mg; calcium stearate 0.5 mg / 1.0 mg / 2.0 mg; talc

0.5 mg / 0.5 mg / 1.0 mg

Doxazosin is marketed under different brands and generic names, and comes in different dosage forms:

Brand name	Manufacturer	Country	Dosage form
Doxazosin-FPO	Obolensky OP	Russia	pills
Cardura®	Pfizer	USA	pills
Doxazosin-Teva	Teva	Israel	pills
Doxazosin	NGO vector	Canada	pills
Kamiren HL	Krka dd Novo mesto AO	Slovenia	pills
Artezin	Valenta	Russia	pills
Camiren	Krka dd Novo mesto AO	Slovenia	pills

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Dosage and Administration

Orally, once a day (in the morning or in the evening), regardless of the meal, without chewing and drinking plenty of water.

Patients with hepatic impairment require smaller doses due to slow metabolism of the drug.

If the patient has forgotten to take the drug at the usual time, he should take the appropriate dose of the drug as soon as possible. If the time is right for taking the next dose, then only her should be taken (without doubling the dose). It is important to take the drug regularly. If the patient has not taken the drug for several days, then the new therapeutic course should be started with the lowest dose.

BPH: the initial dose is 1 mg of doxazosin per day. The patient should take the first dose in the evening before bedtime. Depending on urodynamic indices and the presence of symptoms of BPH, the dose can be gradually increased at intervals of 1–2 weeks to 2 mg, 4 mg and 8 mg per day. The recommended maintenance dose of 2 to 4 mg per day. The maximum daily dose is 8 mg.

After reaching a stable therapeutic effect, the dose is usually reduced (the average therapeutic dose with maintenance therapy is usually 2-4 mg per day).

AH: the initial dose of doxazosin is 1 mg per day at 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 the development of the “first dose” phenomenon, especially pronounced against the background of prior diuretic intake. With a lack of therapeutic effect of the drug, the daily dose can be increased to 2 mg in 1-2 weeks. Subsequently, 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 daily dose is 16 mg.

Adverse reactions

The frequency of adverse reactions with the use of the drug Doxazosin is given below in accordance with the generally accepted classification:

very often (≥1 / 10); often (≥1 / 100,

From the side of the cardiovascular system: often - AH (including orthostatic), palpitations, tachycardia; infrequently - angina, myocardial infarction; very rarely - bradycardia, rhythm disturbances, "flushes" of blood to the skin of the face, peripheral edema.

From the central and peripheral nervous system: often - drowsiness, dizziness, headache; infrequently - stroke, hypoesthesia, syncope, tremor, agitation, depression, anxiety, insomnia, nervousness; very rarely - paresthesia, postural dizziness.

From the senses: often - vertigo; infrequently - ringing in the ears; very rarely - blurred vision, narrow pupil syndrome.

On the part of the digestive system: often - abdominal pain, dyspepsia, dryness of the oral mucosa; infrequently - constipation, abdominal distension, vomiting, diarrhea, increased activity of liver enzymes, loss of appetite, anorexia; very rarely - hepatitis, cholestasis, jaundice.

On the part of the respiratory system: often - bronchitis, cough, shortness of breath, rhinitis, dry nasal mucosa; infrequently - nosebleeds; very rarely bronchospasm.

From the side of blood-forming organs: leukopenia, thrombocytopenia.

On the part of the musculoskeletal system: often - back pain, myalgia; not often - arthralgia; rarely - cramps, weakness in the muscles.

On the part of the skin: often - itching; infrequently - skin rash; very rarely urticaria, alopecia, purpura.

On the part of the genitourinary system: often cystitis, urinary incontinence; not often - dysuria, increased frequency of urination, hematuria, impotence, gout; rarely polyuria; very rarely - an increase in diuresis, urination disorder, nocturia, gynecomastia, priapism, retrograde ejaculation.

General reactions: often - asthenia, chest pain, malaise; infrequently - pain, swelling of the face, weight loss; very rarely - allergic reactions, fatigue.

Contraindications

Hypersensitivity to doxazosin and other quinazoline derivatives (prazosin, terazosin) or to other components of the drug;

Tendency to orthostatic hypotension;

AH (for patients with benign prostatic hyperplasia);

Patients with BPH and a concomitant violation of the outflow of urine from the upper urinary tract, chronic urinary tract infections, stones in the bladder;

Lactose intolerance, lactase deficiency or glucose-galactose malabsorption;

Lactation period;

Age up to 18 years (efficacy and safety have not been established);

As monotherapy in patients with either an overflowing bladder or anuria, with or without a combination of progressive renal failure.

C caution: Pulmonary edema due to aortic or mitral stenosis;

Right-sided heart failure due to pulmonary embolism or pericarditis exudativepravostoronnyaya serdechnaya nedostatochnost? vsledstvie legochno? embolii ili ekssudativny? perikardit;

Left ventricular heart failure with low filling pressure;

The simultaneous use of phosphodiesterase-5 inhibitors (sildenafil, vardenafil, trandalafil);

Syndrome of intraoperative instability of the iris of the eye (narrow pupil syndrome);

Liver dysfunction.

Drug interactions

Doxazosin enhances the antihypertensive effect of antihypertensive drugs (when used in combination with them, dose adjustment is required).

There was no adverse interaction with simultaneous use of doxazosin and thiazide diuretics, furosemide, beta-blockers, blockers of “slow” calcium channels, angiotensin-converting enzyme inhibitors, antibacterial agents, hypoglycemic agents for ingestion, indirect anticoagulants and uricocentric agents.

The drug does not affect the degree of binding to plasma proteins of digoxin, phenytoin.

With simultaneous use of enzymes of microsomal oxidation in the liver (ethanol, barbiturates, phenylbutazone, tricyclic antidepressants) with inducers, it is possible to increase the effectiveness of doxazosin, with inhibitors (cimetidine) - decrease. Non-steroidal anti-inflammatory drugs (NSAIDs), especially indomethacin, estrogens (fluid retention) and sympathomimetic drugs can reduce the hypotensive effect of doxazosin.

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

Concomitant use with selective phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil) can lead to the development of arterial hypotension.

Pregnancy and Lactation

Pregnant women can take the drug only when the benefit to the mother outweighs the potential risk to the fetus / child. There is no data on the penetration of doxazosin into breast milk; therefore, it is recommended that nursing mothers stop feeding during the period of treatment with the drug Doxazosin.

Special instructions

Particular caution should be exercised when using the drug Doxazosin in patients with impaired liver function, especially when using drugs that can alter the “hepatic” metabolism (for example, ethanol, barbiturates, phenylbutazone, tricyclic antidepressants, cimetidine). In cases of deterioration of the functional status of the liver, the drug is immediately canceled.

In order to prevent orthostatic reactions, patients should avoid unexpected and abrupt changes in body position (moving from the "lying" to the "standing" position).

Care should be taken when taking phosphodiesterase-5 and doxazosin inhibitors at the same time. possible development of arterial hypotension. To reduce the risk of arterial hypotension (includingorthostatic) it is necessary to begin treatment with phosphodiesterase-5 inhibitors only if the patient has adapted to doxazosin therapy, and besides, there should be a 6-hour interval between doxazosin intake between drugs.

During surgery for cataracts during the administration of the drug, the syndrome of intraoperative instability of the iris of the eye (narrow pupil syndrome) may develop, which must be considered by the surgeon for the preoperative preparation of the patient and during the operation.

Acceptance of alcohol can increase the adverse reactions of doxazosin.

The effect of the “first dose” of the drug is especially pronounced against the background of previous diuretic therapy and a sodium-restricted diet.

Before starting therapy, it is necessary to exclude cancer prostate degeneration.

Impact on the ability to drive vehicles and other mechanisms

In the case of taking the drug Doxazosin, caution should be exercised when driving or when performing work that requires high concentration of attention and speed of psychomotor reactions.

Overdosage

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

Treatment: gastric lavage, taking activated carbon. The patient must be laid on his back and lift his legs. With a pronounced decrease in blood pressure, anti-shock measures are taken - they fill the circulating blood volume, and, if necessary, they are prescribed vasopressors.

Hemodialysis is ineffective.