Doxazosin mesylate, a quinazoline compound sold by Pfizer under the brand names Cardura and Carduran, is an α1-selective alpha blocker used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia (BPH).
On February 22, 2005, the US FDA approved a sustained release form of doxazosin, to be marketed as Cardura XL.
It is an alpha-1 adrenergic receptor blocker that inhibits the binding of norepinephrine (released from sympathetic nerve terminals) to the alpha-1 receptors on the membrane of vascular smooth muscle cells. The primary effect of this inhibition is relaxed vascular smooth muscle tone (vasodilation), which decreases peripheral vascular resistance, leading to decreased blood pressure.
Doxazosin and similar medications like prazosin have been found to help reduce the intensity of and/or stop posttraumatic stress disorder night terrors and nightmares. The full reasoning of this effect is not understood.
In Egypt, tablet formulation sold as Duracin produced by Biopharm group for research and the drug industry, Dosin by Eipico and Doxazocine by Multi-Apex.
In March 2000, the ALLHAT study stopped its arm of the trial looking at alpha blockers, because doxazosin was less effective than a simple diuretic, and because patients on doxazosin had a 25% higher rate of cardiovascular disease and twice the rate of congestive heart failure as patients on diuretics. Pfizer, aware of the results before publication, launched a marketing campaign in early 2000, and sales were largely unaffected, despite the dangers highlighted by the study. Doxazosin shows potential for treatment of benign prostatic hyperplasia and erectile dysfunction.
Doxazosin has also shown some efficacy in treating chronic epididymitis.
INDICATION AND DOSAGE
Adult: As mesilate: Initially, 1 mg at bedtime increased after 1-2 wk according to response. Maintenance: 4 mg once daily. Max: 16 mg daily.
Benign prostatic hyperplasia
Adult: As mesilate: Initially, 1 mg once daily at bedtime increased after 1-2 wk; monitor BP after 2-6 hr. Maintenance: 2-4 mg daily. Max: 8 mg daily
Contraindications Known hypersensitivity to quinazolines.
Special Precautions Renal or hepatic impairment. Prostatic carcinoma should be ruled out before starting therapy. Orthostatic hypotension may occur at the initiation of therapy or when there is dose increase. Avoid driving or performing hazardous tasks for 24 hr after starting therapy or dose changes. Pregnancy and lactation.
Adverse Drug Reactions Chest pain, fatigue, headache, influenza-like symptoms, pain, hypotension, palpitation, abdominal pain, diarrhoea, nausea, oedema, dizziness, dry mouth, somnolence, dyspnoea, respiratory disorders, vision abnormalities, impotence, urinary tract infection, increased sweating, anxiety, insomnia. Vertigo, orthostatic hypotension, arrhythmia, hypotension, arthralgia/arthritis, muscle weakness, myalgia, kinetic disorders, ataxia, hypertonia, muscle cramps, flushing, tinnitus, sexual dysfunction, rhinitis, epistaxis, polyuria, urinary incontinence, fatigue/malaise, face oedema.
BRAND - DOXACARD