Doxazosin

DOXAZOSIN- doxazosin mesylate tablet
Mylan Institutional Inc.

1 INDICATIONS AND USAGE

1.1 Benign Prostatic Hyperplasia (BPH)

Doxazosin tablets are indicated for the treatment of the signs and symptoms of BPH.

1.2 Hypertension

Doxazosin tablets are indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes, including this drug.

Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program’s Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC).

Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly.

Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal.

Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy.

Doxazosin tablets may be used alone or in combination with other antihypertensives.

2 DOSAGE AND ADMINISTRATION

2.1 Dosing Information

Following the initial dose and with each dose increase of doxazosin tablets, monitor blood pressure for at least 6 hours following administration. If doxazosin tablets administration is discontinued for several days, therapy should be restarted using the initial dosing regimen.

2.2 Benign Prostatic Hyperplasia

The recommended initial dosage of doxazosin tablets is 1 mg given once daily either in the morning or evening.

Depending on the individual patient’s urodynamics and BPH symptomatology, the dose may be titrated at 1 to 2 week intervals to 2 mg, and thereafter to 4 mg and 8 mg once daily. The maximum recommended dose for BPH is 8 mg once daily.

Routinely monitor blood pressure in these patients.

2.3 Hypertension

The initial dosage of doxazosin tablets is 1 mg given once daily. Daily dosage may be doubled up 16 mg once daily, as needed, to achieve the desired reduction in blood pressure.

3 DOSAGE FORMS AND STRENGTHS

Doxazosin Tablets, USP are available containing doxazosin mesylate, USP equivalent to 1 mg, 2 mg, 4 mg or 8 mg of doxazosin.

  • The 1 mg tablets are white to off-white, round tablets debossed with M over D9 on one side of the tablet and scored on the other side.
  • The 2 mg tablets are pink, round tablets debossed with M over D10 on one side of the tablet and scored on the other side.
  • The 4 mg tablets are blue, round tablets debossed with M over D11 on one side of the tablet and scored on the other side.
  • The 8 mg tablets are purple, round tablets debossed with M over D12 on one side of the tablet and scored on the other side.

4 CONTRAINDICATIONS

The use of doxazosin tablets is contraindicated in patients with a hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any of its components.

5 WARNINGS AND PRECAUTIONS

5.1 Postural Hypotension

Postural hypotension with or without symptoms (e.g., dizziness) may develop within a few hours following administration of doxazosin tablets. However, infrequently, symptomatic postural hypotension has also been reported later than a few hours after dosing. As with other alpha-blockers, there is a potential for syncope, especially after the initial dose or after an increase in dosage strength. Advise patient how to avoid symptoms resulting from postural hypotension and what measures to take should they develop.

Concomitant administration of doxazosin tablets with a PDE-5 inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.

5.2 Cataract Surgery

Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on or previously treated with alpha 1 blockers. This variant of small pupil syndrome is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. The patient’s surgeon should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. There does not appear to be a benefit of stopping alpha 1 blocker therapy prior to cataract surgery.

5.3 Prostate Cancer

Carcinoma of the prostate causes many of the symptoms associated with BPH and the two disorders frequently co-exist. Carcinoma of the prostate should therefore be ruled out prior to commencing therapy with doxazosin tablets for the treatment of BPH.

5.4 Priapism

Alpha 1 antagonists, including doxazosin, have been associated with priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation). This condition can lead to permanent impotence if not promptly treated.

6 ADVERSE REACTIONS

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Benign Prostatic Hyperplasia (BPH)

The incidence of adverse events has been ascertained from worldwide clinical trials in 965 BPH patients. The incidence rates presented below (Table 2) are based on combined data from seven placebo-controlled trials involving once-daily administration of doxazosin tablets in doses of 1 mg to 16 mg in hypertensives and 0.5 mg to 8 mg in normotensives. Adverse reactions occurring more than 1% more frequently in BPH patients treated with doxazosin tablets versus placebo are summarized in Table 1.

Table 1. Adverse Reactions Occurring more than 1% More Frequently in BPH Patients Treated with Doxazosin Tablets versus Placebo
*
Includes vertigo

BODY SYSTEM

Doxazosin Tablets

N = 665

Placebo

N = 300

NERVOUS SYSTEM DISORDERS

Dizziness *

15.6%

9.0%

Somnolence

3.0%

1.0%

CARDIAC DISORDERS

Hypotension

1.7%

0%

RESPIRATORY, THORACIC AND MEDIASTINAL DISORDERS

Dyspnoea

2.6%

0.3%

GASTROINTESTINAL DISORDERS

Dry Mouth

1.4%

0.3%

GENERAL DISORDERS AND ADMINISTRATION SITE CONDITIONS

Fatigue

8.0%

1.7%

Oedema

2.7%

0.7%

Other adverse reactions occurring less than 1% more frequently in BPH patients treated with doxazosin tablets versus placebo but plausibly related to doxazosin tablets include: palpitations.

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