Information about Terazosin
Mechanism of action of Terazosin
Terazosin (ter ay' zoe sin) was the second alpha-1 adrenergic antagonist to be approved for use in the United States and is still widely used for therapy of hypertension and benign prostatic hypertrophy. Terazosin inhibits alpha-adrenergic receptors present on smooth muscle in arterioles (so-called alpha-1b adrenergic receptors) as well as in those in the bladder neck and prostate (alpha-1a adrenergic receptors). The inhibition of alpha-adrenergic tone in blood vessels causes relaxation of arteriolar resistance and lowering of the blood pressure.
FDA approval information for Terazosin
Terazosin was approved for use in the United States in 1987 and is still used for treatment of hypertension, although rarely as a first line agent and usually in combination with other antihypertensive drugs. Terazosin is also approved for alleviation of the symptoms of urinary obstruction due to benign prostatic hypertrophy. More than 4 million prescriptions for terazosin are filled yearly in the United States.
Dosage and administration for Terazosin
Terazosin is available in tablets or capsules of 1, 2, 5 and 10 mg generically and under the trade name Hytrin. Terazosin is usually started at a dose of 1 mg daily at bedtime with increase in the dose based upon tolerance and clinical response to an average of 5 to 10 mg daily in one dose daily, usually at bedtime.
Side effects of Terazosin
Side effects include dizziness and syncope (particularly with the initial dose), fatigue, headache, palpitations, impotence, incontinence and gastrointestinal upset. Rare, but potentially severe adverse events include postural hypotension and priapism.
Liver safety of Terazosin
Terazosin therapy is associated with a low rate of transient serum aminotransferase elevations and to rare instances of clinically apparent acute liver injury.