Classifications: alpha-adrenergic antagonist; Therapeutic: antihypertensive
Pregnancy Category: B
1 mg, 2 mg, 4 mg, 8 mg tablets
By selective competitive inhibition of alpha1-adrenoreceptors, it produces vasodilation in both arterioles and veinous vessels with the result that both peripheral vascular
resistance and blood pressure are reduced.
Long-acting effect of lowering blood pressure in supine or standing individuals with most pronounced effect on diastolic
Mild to moderate hypertension, benign prostatic hypertrophy.
Hypersensitivity to doxazosin, prazosin, and terazosin; hypotension, syncope. Safe use in children is not established.
Hepatic impairment or disease; renal disease, impairment, or failure; pregnancy (category B); lactation.
Route & Dosage
Adult: PO Start with 1 mg h.s. and titrate up to maximum of 16 mg/d in 12 divided doses
Geriatric: PO Start with 0.5 mg h.s.
- Give initial dose at bedtime to minimize problems with postural hypotension and syncope.
- Individualize maintenance dose according to the standing BP response.
- Store at 15°30° C (59°86° F).
Adverse Effects (≥1%)CV: Orthostatic hypotension,
dizziness, somnolence, fatigue
, nervousness, anxiety. GI:
Nausea, abdominal pain. Hematologic: Leukopenia
InteractionsDrug: Sildenafil, vardenafil,
may enhance hypotensive effects.
Readily absorbed from GI tract; 6269% of dose reaches systemic circulation. Peak:
26 h. Duration:
Up to 24 h. Distribution:
Highly protein bound (9899%). Metabolism:
Approximately 35% of dose is metabolized in liver. Elimination:
9% in urine, 63% in feces. Half-Life:
Assessment & Drug Effects
- Monitor BP with patient lying down and standing; doses above 4 mg increase the risk of postural hypotension.
- Monitor BP 26 h after initial dose or any dose increase. This is when postural hypotension is most likely to occur.
Patient & Family Education
- Do not drive or engage in other potentially hazardous activities for 1224 h after the first dose or an increase in
dosage or when medication is restarted after an interruption in dosage.
- Use caution when rising from a sitting or supine position in order to avoid orthostatic hypotension and syncope; make position
and directional changes slowly and in stages.
- Report to the physician episodes of dizziness or palpitations. These will require a dosage adjustment.