Cardura

Car·dur·a (kär-dr)

A trademark for the drug doxazosin mesylate.

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doxazosin mesylate

Cardura, Doxadura (UK)

Pharmacologic class: Sympatholytic, peripherally acting antiadrenergic

Therapeutic class: Antihypertensive

Pregnancy risk category C

Action

Blocks alpha₁-adrenergic receptors, promoting vasodilation. Also reduces urethral resistance, relieving obstruction and improving urine flow and other symptoms of benign prostatic hypertrophy (BPH).

Availability

Tablets: 1 mg, 2 mg, 4 mg, 8 mg

⊘Indications and dosages

➣ Hypertension

Adults: 1 mg P.O. once daily. May increase dosage gradually q 2 weeks, up to 2 to 16 mg daily, as needed.

➣ BPH

Adults: 1 mg P.O. once daily. May increase dosage gradually, up to 8 mg daily, as needed.

Off-label uses

• Pheochromocytoma
• Syndrome X

Contraindications

• Hypersensitivity to drug or quinazoline derivatives

Precautions

Use cautiously in:
• renal or hepatic impairment, heart failure
• elderly patients
• pregnant or breastfeeding patients
• children (safety not established).

Administration

• Give initial dose at bedtime to minimize orthostatic hypotension and syncope.
• Know that incidence of orthostatic hypotension increases greatly when daily dosage exceeds 4 mg and that it usually occurs within 6 hours of administration.

Route	Onset	Peak	Duration
P.O.	1-2 hr	2-6 hr	24 hr

Adverse reactions

CNS: dizziness, vertigo, headache, depression, drowsiness, fatigue, nervousness, weakness, asthenia

CV: orthostatic hypotension, chest pain, palpitations, tachycardia, arrhythmias

EENT: abnormal or blurred vision, conjunctivitis, epistaxis, rhinitis, pharyngitis

GI: nausea, vomiting, diarrhea, constipation, abdominal discomfort, flatulence, dry mouth

GU: decreased libido, sexual dysfunction

Respiratory: dyspnea

Musculoskeletal: joint pain, arthritis, gout, myalgia

Skin: flushing, rash, pruritus

Other: edema

Interactions

Drug-drug. Clonidine, nitrates, other antihypertensives: decreased antihypertensive effect

Drug-diagnostic tests. Neutrophils, white blood cells: decreased counts

Drug-herbs. Butcher's broom: decreased doxazosin effects

Drug-behaviors. Alcohol use: additive hypotension

Patient monitoring

• Monitor blood pressure with patient lying down and standing up every 2 to 6 hours after initial dose or after a dosage increase (when orthostatic hypotension is most likely to occur).

Patient teaching

• Caution patient not to drive or perform other activities requiring alertness for 12 to 24 hours after first dose.
• Tell patient to move slowly when sitting up or standing, to avoid dizziness or light-headedness from sudden blood pressure decrease.
• Advise patient to report episodes of dizziness or palpitations.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.