Class: Alpha-1-adrenergic blocker
- Capsules 1 mg
- Capsules 2 mg
- Capsules 5 mg
- Capsules 10 mg
Selectively blocks postsynaptic alpha 1 -adrenergic receptors, resulting in dilation of arterials and veins.
Oral terazosin is completely absorbed. Food delayed the time to peak concentration by 1 h. T max occurs 1 h after dosing.
Terazosin is 90% to 94% bound to plasma proteins.
Terazosin undergoes minimal first-pass metabolism.
Terazosin t ½ is approximately 12 h. Approximately 40% of an orally administered dose is excreted in urine and approximately 60% is excreted in feces.
After oral administration, plasma Cl was decreased 31.7% in patients older than 70 yr of age vs patients 20 to 39 yr of age.
Indications and Usage
Management of hypertension and symptomatic benign prostatic hyperplasia (BPH).
Hypersensitivity to doxazosin or prazosin.
Dosage and AdministrationHypertension
PO Initial: 1 mg at bedtime. (Do not exceed this as initial dose to avoid severe hypotensive effects; reinstitute at this dose if drug is discontinued for several days). Maintenance: 1 to 5 mg every day; may consider twice daily dosing (max, 20 mg/day).BPH
1 mg at bedtime. (Do not exceed this as initial dose); increase dose in step-wise fashion.Usual maintenance
10 mg every day for minimum of 4 to 6 wk (max, 20 mg/day).
Store in tight container in cool location.
None well documented.
Laboratory Test Interactions
None well documented.
Palpitations; orthostatic hypotension; hypotension; tachycardia; arrhythmias; vasodilation.
Dizziness; nervousness; paresthesia; somnolence; anxiety; headache; insomnia; weakness; drowsiness.
Pruritus; rash; sweating.
Blurred or abnormal vision; conjunctivitis; tinnitus; nasal congestion; sinusitis; epistaxis; pharyngitis.
Nausea; vomiting; dry mouth; diarrhea; constipation; abdominal discomfort or pain; flatulence.
Impotence; urinary frequency; UTI.
Dyspnea; bronchitis; bronchospasm; flu symptoms; increased cough.
Shoulder, neck, back, or extremity pain; arthralgia; edema; fever; weight gain.
Category C .
Safety and efficacy not established.
Long-term effects on incidence of surgery, acute urinary obstruction, or other complications of BPH have not been determined.
May cause marked hypotension (especially orthostatic) and syncope at 15 to 90 min after first few doses, after reintroduction, with rapid increase in dosing, or after addition of another antihypertensive; to avoid, initiate dosing with low dose and gradually increase after 2 wk; monitor patients carefully.
Small decreases in hematocrit, hemoglobin, WBCs, total protein, and albumin may occur, possibly because of hemodilution.
- Explain to patient that first few doses may cause hypotension and syncope. Therefore, initially, terazosin should be taken at bedtime and patient should be warned to stay prone after taking dose. After first few doses, orthostatic hypotension with syncope is rare.
- Advise patient to avoid OTC cough, cold, and allergy medicines containing sympathomimetics, and identify common examples.
- Instruct patient to avoid driving or other activities that require alertness for first 24 h after initial dose.
- Advise patient to follow up with health care provider to monitor BP.
- Caution patient to rise slowly from lying or sitting position to minimize dizziness.
- Instruct patient to report these symptoms to health care provider: dizziness, visual changes, palpitations.
- Alert male patients that impotence may be an adverse reaction.
- Explain potential adverse reactions: arthralgia, weight gain, tinnitus, pruritus, epistaxis, blurred vision. Be certain patient understands that health care provider should be made aware of any significant adverse reactions.
- Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
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