Class: α1-Adrenergic Blocker
Dosage Forms. Tablet: 1 mg, 2 mg, 4 mg, 8 mg; Tablet, Extended Release: 4 mg, 8 mg
Common FDA Label Indication, Dosing, and Titration.
1. Benign prostatic hyperplasia: Immediate release, 1 mg po daily, titrate to 1-8 mg po daily; Extended release, 4 mg po daily, titrate to 8 mg po daily
2. Hypertension: 1 mg po daily, titrate to 16 mg po daily
1. Disorder of the urinary system: 2 mg po daily hs
MOA. Doxazosin selectively blocks postsynaptic a1-adrenergic receptors, reducing peripheral resistance through arterial and venous dilatations. Reflex tachycardia that occurs with other vasodilators is infrequent because there is no presynaptic α2-receptor blockade. Increase urine flow by relaxing smooth muscle tone in the bladder neck and prostate.
Drug Characteristics: Doxazosin
Medication Safety Issues: Doxazosin
Drug Interactions: Doxazosin
Adverse Reactions: Doxazosin
Efficacy Monitoring Parameters. Decreased BP, improvement in urinary symptoms.
Toxicity Monitoring Parameters. Signs of hypotension, increased heart rate.
Key Patient Counseling Points. Initial dose should be taken with breakfast. Avoid activities requiring coordination until drug effects are realized, as drug may cause vertigo or dizziness. Rise slowly from a sitting/lying position, as this drug may cause orthostatic hypotension. Syncope or loss of consciousness is possible with first dose or dose increases, especially if patient is in an upright position.
Clinical Pearls. Safety and effectiveness not established in children.