What It Is

Doxazosin is a medication primarily used to treat high blood pressure (hypertension) and benign prostatic hyperplasia (BPH), a condition in which the prostate gland becomes enlarged. It belongs to a class of drugs known as alpha-1 adrenergic blockers or antagonists.

Dosage Forms and Strengths

Doxazosin is available in various dosage forms, including:

• Tablets: These are the most common form and are available in strengths of 1 mg, 2 mg, 4 mg, and 8 mg.

Brand and Generic Names

• Brand Names: Cardura, Cardura XL (extended-release formulation).
• Generic Name: Doxazosin.

Indications for Use

Doxazosin is prescribed for:

1. Hypertension: It helps lower blood pressure by relaxing blood vessels.
2. Benign Prostatic Hyperplasia (BPH): It alleviates symptoms such as difficulty in urination by relaxing the muscles in the prostate and bladder neck.

Mechanism of Action

Doxazosin works by selectively blocking alpha-1 adrenergic receptors, which are found in the smooth muscles of blood vessels and the prostate. By inhibiting these receptors, doxazosin causes the blood vessels to relax and dilate, thereby reducing blood pressure. In the prostate, this relaxation helps to ease urinary symptoms associated with BPH.

Administration and Dosage

• Hypertension: The usual starting dose is 1 mg once daily, which can be gradually increased based on the patient’s response and tolerance. The typical maintenance dose ranges from 1 mg to 16 mg per day.
• Benign Prostatic Hyperplasia: The initial dose is usually 1 mg once daily. Depending on the patient's response, the dose may be adjusted up to a maximum of 8 mg per day.

Doxazosin is typically administered orally and can be taken with or without food. The extended-release formulation (Cardura XL) is usually taken once daily.

Side Effects and Precautions

Common Side Effects:

• Dizziness
• Fatigue
• Headache
• Drowsiness
• Nasal congestion

Serious Side Effects:

• Orthostatic hypotension (a sudden drop in blood pressure when standing up)
• Severe allergic reactions (e.g., rash, itching, swelling)
• Priapism (a prolonged and painful erection)

Precautions:

• Orthostatic Hypotension: Patients should be advised to rise slowly from a sitting or lying position to avoid dizziness and fainting.
• Preexisting Conditions: Caution is advised in patients with a history of prostate cancer or severe liver impairment.
• Drug Interactions: Doxazosin may interact with other medications, including other antihypertensives and drugs that affect liver enzymes.

Conclusion

Doxazosin is a valuable medication for managing hypertension and symptoms of benign prostatic hyperplasia. By targeting alpha-1 adrenergic receptors, it effectively reduces blood pressure and alleviates urinary difficulties. While generally well-tolerated, it is important for patients to be aware of potential side effects and to follow dosing instructions carefully. As with any medication, a healthcare provider should be consulted to ensure its suitability for individual health needs and to manage any possible interactions or side effects.

INDICATION AND DOSAGE OF DOXAZOSIN