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Pharmacologic class: Anti-adrenergic (peripherally acting)
Therapeutic class: Antihypertensive
Pregnancy risk category C
Blocks postsynaptic alpha1-adrenergic receptors, causing vasodilation and decreasing smooth muscle contractions in bladder neck and prostate
Capsules: 1 mg, 2 mg, 5 mg, 10 mg
Indications and dosages
Adults: Initially, 1 mg P.O., increased slowly as needed up to 5 mg/day. Usual range is 1 to 5 mg/day, not to exceed 20 mg/day.
➣ Benign prostatic hyperplasia
Adults: 1 mg P.O. at bedtime. To achieve desired response, may increase gradually to 2 mg/day, then to 5 mg/day, and then to a maximum of 10 mg/day.
• Hypersensitivity to drug or other quinazoline derivatives
Use cautiously in:
• prostate cancer, hepatic disease, dehydration, volume or sodium depletion
• pregnant or breastfeeding patients
• children (safety not established).
Don't stop therapy suddenly. Dosage must be tapered.
• Know that drug may be given as a single dose at bedtime or in two divided doses.
CNS: dizziness, headache, weakness, drowsiness, nervousness, paresthesia, vertigo, fatigue, syncope
CV: orthostatic hypotension (with first dose), rebound hypertension, chest pain, palpitations, peripheral edema, tachycardia, arrhythmias
EENT: blurred vision, conjunctivitis, amblyopia, nasal congestion, sinusitis
GI: nausea, vomiting, diarrhea, abdominal pain, dry mouth
GU: urinary frequency or incontinence, erectile dysfunction, priapism
Musculoskeletal: joint, back, and extremity pain; arthritis
Other: fever, weight gain, flulike symptoms
Drug-drug. Estrogens, nonsteroidal anti-inflammatory drugs (NSAIDs), sympathomimetics: decreased antihypertensive effects
Midodrine: antagonism of terazosin's action
Nitrates, other antihypertensives: additive hypotension
Drug-herbs. Ephedra (ma huang): antagonism of terazosin's action
Drug-behaviors. Alcohol use: additive hypotension
• Monitor blood pressure. Stay alert for orthostatic hypotension (first-dose effect) when therapy begins.
• Assess cardiovascular status. Report chest pain, peripheral edema, palpitations, and other significant effects.
• Instruct patient to take at same time every day, with or without food.
Caution patient not to stop therapy abruptly. Dosage must be tapered.
Advise patient to immediately report swelling, breathing difficulty, palpitations, chest pain, and other cardiovascular reactions.
• Tell patient drug may cause erectile dysfunction and other sexual problems.
• Caution patient not to use NSAIDs or drink alcohol.
• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure decrease.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, herbs, and behaviors mentioned above.