Doxazosin Mesylate

 Action Selectively blocks postsynaptic alpha-1-adrenergic receptors, resulting in dilation of arterioles and veins.

 Indications Treatment of hypertension, alone or in combination with other agents; treatment of benign prostatic hyperplasia (BPH).

 Contraindications Hypersensitivity to prazosin or terazosin.

 Route/Dosage

Hypertension Adults: Initial dose: PO 1 mg qd. Maintenance: Based on standing BP response, may increase to 2 mg and thereafter to 4, 8, and 16 mg.

Benign Prostatic Hyperplasia Adults: Initial dose: PO 1 mg/day. Maintenance: Increase to 2 mg, and thereafter to 4 and 8 mg once daily, which is the max dose for BPH. Recommended titration interval is 1 to 2 wk.

 Interactions

None well documented.

 Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: Palpitations; orthostatic hypotension; hypotension; arrhythmia; chest pain. CNS: Depression; dizziness; decreased libido; sexual dysfunction; nervousness; paresthesia; somnolence; headache; anxiety; insomnia; asthenia; ataxia; hypertonia. DERMATOLOGIC: Pruritus; rash; sweating. EENT: Abnormal vision; conjunctivitis; tinnitus; rhinitis; epistaxis; pharyngitis. GI: Nausea; vomiting; dry mouth; diarrhea; constipation; abdominal discomfort or pain; flatulence. GU: Incontinence; polyuria. RESPIRATORY: Dyspnea. OTHER: Shoulder, neck, back or extremity pain; arthritis; joint or muscle pain; gout; arthralgia; vertigo; edema; facial edema; flushing.

 Precautions

Pregnancy: Category C. Lactation: Excreted in breast milk. Children: Safety and efficacy not established. “First-dose” effect: Marked hypotension (especially orthostatic) and syncope may occur at 2 to 6 hr after first few doses, after reintroduction, with rapid increase in dosing or after addition of another antihypertensive. Hepatic impairment: Use drug with extreme caution. Lipids: Slight decrease in total serum cholesterol and LDL may occur as well as increase in HDL.

 Administration/Storage

• Have patient swallow tablet whole. Do not crush or allow patient to chew tablet.
• Give first dose at bedtime to decrease possibility of orthostatic hypotension, dizziness, and syncope.
• Store at room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note any history of liver failure.
• Record patient's weight daily.
• Monitor BP and pulse 2 to 6 hr after initial dose and each increase and daily throughout therapy.
• Monitor LFTs, CBC, cholesterol, LDL, HDL, BUN, creatinine, and triglycerides.
• Monitor I&O.
• Monitor for chest pain and arrhythmia. Notify health care provider if these signs are present.
• Monitor patient for nausea, vomiting, abdominal distention, or pain.
• Monitor for edema. Check patient's feet and legs daily for swelling.
• Observe skin for rash or diaphoresis.

 Patient/Family Education

• Remind patient to take tablets whole and to not crush or chew tablets.
• Teach patient how to take BP. Advise patient to monitor weekly and to notify health care provider if significant changes occur.
• Emphasize importance of reducing the following risk factors: smoking cessation, weight loss, discontinuation of dietary intake of fat, exercise.
• Caution patient not to discontinue medication, even if feeling well, unless directed by health care provider.
• Instruct patient to record weight 3 times/wk.
• Advise patient to report the following symptoms to health care provider: nausea, vomiting or diarrhea; dizziness; chest pain or palpitations; swelling of feet or ankles.
• Caution patient to avoid sudden position changes 2 to 6 hr after taking medication to prevent orthostatic hypotension and syncope.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct patient not to take OTC medications without consulting health care provider.