What category of medication is terazosin (alpha-1 adrenergic blocker)?

Terazosin Drug Classification

Terazosin is an alpha-1 adrenergic blocker (alpha-1 adrenoceptor antagonist). 1

Mechanism of Action

• Terazosin selectively antagonizes alpha-1 adrenergic receptors, inhibiting alpha-1 adrenergic-mediated contraction of prostatic smooth muscle and vascular smooth muscle. 2, 1
• In benign prostatic hyperplasia (BPH), this mechanism relieves bladder outlet obstruction by relaxing smooth muscle in the prostate, prostatic capsule, proximal urethra, and bladder base. 2, 3
• In hypertension, terazosin reduces peripheral vascular resistance through vasodilation. 1

Clinical Classification Context

Terazosin is classified as a non-selective (non-uroselective) alpha-1 blocker, distinguishing it from uroselective agents like tamsulosin and alfuzosin. 4

• Non-selective alpha-1 blockers (terazosin, doxazosin) have greater systemic cardiovascular effects including orthostatic hypotension, dizziness, and fatigue compared to uroselective agents. 4
• This non-selectivity explains terazosin's dual FDA approval for both hypertension and BPH, whereas uroselective agents are primarily indicated for BPH. 1, 5

Pharmacologic Properties

• Terazosin is a quinazoline derivative with selective alpha-1 receptor antagonism (as opposed to non-selective alpha blockade affecting both alpha-1 and alpha-2 receptors). 1, 3
• The drug has a relatively long duration of action allowing once-daily dosing. 3, 6
• Terazosin demonstrates dose-dependent efficacy, with higher doses providing greater therapeutic benefit but also increased adverse effects. 2, 7

Regulatory Classification

• Terazosin was initially approved as an antihypertensive agent and subsequently received FDA approval in 1993 for treatment of symptomatic BPH. 5
• The drug is available in oral capsule formulations at 1 mg, 2 mg, 5 mg, and 10 mg strengths. 1