Terazosin

Brand Names: Hytrin

Drug Class: Alpha-1 adrenergic blocker

Overview

Terazosin is an alpha-1 adrenergic blocker used to treat hypertension and symptomatic benign prostatic hyperplasia (BPH). It works by relaxing blood vessels and prostate/urethral smooth muscle, improving urinary flow in BPH and lowering blood pressure. The drug is typically administered orally in capsule form with dose titration to minimize first-dose hypotension.

Mechanism of Action

Terazosin selectively blocks postsynaptic alpha-1 adrenergic receptors, causing vasodilation of both arteries and veins (reducing peripheral vascular resistance) and relaxation of smooth muscle in the prostate and bladder neck (improving urinary flow).

Indications

  • Treatment of symptomatic benign prostatic hyperplasia (BPH) to improve urinary flow and symptoms
  • Treatment of hypertension, either as monotherapy or in combination with other antihypertensive agents

Common Doses

  • 1 mg
  • 2 mg
  • 5 mg
  • 10 mg

Dosage

Initial dose typically 1 mg at bedtime, titrated upward based on response and tolerability. For BPH: usual dose 5-10 mg daily. For hypertension: usual dose 1-20 mg daily in single or divided doses. If therapy is interrupted for several days, restart with initial dosing regimen.

Contraindications

  • Hypersensitivity to terazosin hydrochloride or any component of the formulation

Side Effects

  • Dizziness, headache, asthenia (weakness)
  • Postural hypotension, syncope (especially with first dose)
  • Nasal congestion, peripheral edema
  • Palpitations, tachycardia
  • Blurred vision, somnolence
  • Nausea, gastrointestinal discomfort

Interactions

  • Additive hypotensive effects with other antihypertensives, nitrates, phosphodiesterase-5 inhibitors
  • Enhanced first-dose hypotension with concomitant beta-blockers
  • No clinically significant interactions observed with analgesics, antibiotics, anticholinergics, corticosteroids, or gastrointestinal agents in clinical studies

Counseling Points

  • Take first dose at bedtime to minimize risk of fainting
  • Rise slowly from sitting/lying position to prevent dizziness
  • Report dizziness, lightheadedness, or palpitations to healthcare provider
  • Do not interrupt therapy without medical advice; if missed for several days, contact provider before restarting
  • Avoid alcohol which may worsen dizziness and hypotension
  • Inform all healthcare providers about terazosin use before surgery