Blocks postsynaptic alpha-1-receptors

Dosing: Adult

BPH: Oral:

Immediate release: 1 mg once daily in morning or evening; may be increased to 2 mg once daily. Thereafter titrate upwards, if needed, over several weeks, balancing therapeutic benefit with doxazosin-induced postural hypotension. Goal: 4-8 mg/day; maximum dose: 8 mg/day

Reinitiation of therapy: If therapy is discontinued for several days, restart at 1 mg dose and titrate as before

Extended release: 4 mg once daily with breakfast; titrate based on response and tolerability every 3-4 weeks to maximum recommended dose of 8 mg/day

Reinitiation of therapy: If therapy is discontinued for several days, restart at 4 mg dose and titrate as before

Note: Conversion to extended release from immediate release: Omit final evening dose of immediate release prior to starting morning dosing with extended release product; initiate extended release product using 4 mg once daily

Hypertension: Oral: Immediate release: 1 mg once daily in morning or evening; may be increased to 2 mg once daily. Thereafter titrate upwards, if needed, over several weeks, balancing therapeutic benefit with doxazosin-induced postural hypotension. Maximum dose: 16 mg/day

Reinitiation of therapy: If therapy is discontinued for several days, restart at 1 mg dose and titrate as before

Dosing: Pediatric

Hypertension (unlabeled use): Oral: Immediate release: Initial: 1 mg once daily; maximum: 4 mg/day

Dosing: Geriatric

Refer to adult dosing. In the management of hypertension, consider lower initial doses (eg, immediate release: 0.5 mg once daily) and titrate to response (Aronow, 2011)

Dosing: Hepatic Impairment

Use with caution in mild-to-moderate hepatic dysfunction. Do not use with severe impairment.

Dosage Forms: U.S.

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, oral: 1 mg, 2 mg, 4 mg, 8 mg

Cardura®: 1 mg, 2 mg, 4 mg, 8 mg [scored]

Tablet, extended release, oral:

Cardura® XL: 4 mg, 8 mg

Generic Equivalent Available: U.S.

Yes: Excludes extended release tablet

Administration

Cardura® XL: Tablets should be swallowed whole; do not crush, chew, or divide. Administer with morning meal.

Use

Immediate release formulation: Treatment of hypertension as monotherapy or in conjunction with diuretics, ACE inhibitors, beta-blockers, or calcium antagonists

Immediate release and extended release formulations: Treatment of urinary outflow obstruction and/or obstructive and irritative symptoms associated with benign prostatic hyperplasia (BPH)

Use - Unlabeled/Investigational

Pediatric hypertension

Adverse Reactions Significant

Note: Type and frequency of adverse reactions reflect combined data from BPH and hypertension trials and immediate release and extended release products.

>10%: Central nervous system: Dizziness (5% to 19%), headache (5% to 14%)

1% to 10%:

Cardiovascular: Orthostatic hypotension (dose related; 0.3% up to 2%), edema (3% to 4%), hypotension (1% to 2%), palpitation (1% to 2%), chest pain (1% to 2%), arrhythmia (1%), syncope (2%), flushing (1%)

Central nervous system: Fatigue (8% to 12%), somnolence (1% to 5%), nervousness (2%), pain (2%), vertigo (2% to 4%), insomnia (1%), anxiety (1%), paresthesia (1%), movement disorder (1%), ataxia (1%), hypertonia (1%), depression (1%)

Dermatologic: Rash (1%), pruritus (1%)

Endocrine & metabolic: Sexual dysfunction (2%)

Gastrointestinal: Abdominal pain (2%), diarrhea (2%), dyspepsia (1% to 2%), nausea (1% to 3%), xerostomia (1% to 2%), constipation (1%), flatulence (1%)

Genitourinary: Urinary tract infection (1%), impotence (1%), polyuria (2%), incontinence (1%)

Neuromuscular & skeletal: Back pain (2% to 3%), weakness (1% to 7%), arthritis (1%), muscle weakness (1%), myalgia (≤1%), muscle cramps (1%)

Ocular: Abnormal vision (1% to 2%), conjunctivitis (1%)

Otic: Tinnitus (1%)

Respiratory: Respiratory tract infection (5%), rhinitis (3%), dyspnea (1% to 3%), respiratory disorder (1%), epistaxis (1%)

Miscellaneous: Diaphoresis increased (1%), flu-like syndrome (1%)

<1% (Limited to important or life-threatening): Abnormal thinking, agitation, allergic reaction, amnesia, angina, anorexia, appetite increased, bradycardia, breast pain, bronchospasm, cerebrovascular accident, cholestasis, confusion, depersonalization, emotional lability, fecal incontinence, fever, gastroenteritis, gout, gynecomastia, hematuria, hepatitis, hypoesthesia, hypokalemia, infection, intraoperative floppy iris syndrome (cataract surgery), jaundice, leukopenia, liver function tests increased, lymphadenopathy, MI, micturition abnormality, migraine, neutropenia, nocturia, pallor, paranoia, paresis, paresthesia, parosmia, peripheral ischemia, priapism, purpura, renal calculus, rigors stroke, syncope, tachycardia, thrombocytopenia, urticaria, vomiting

Contraindications

Hypersensitivity to quinazolines (prazosin, terazosin), doxazosin, or any component of the formulation

Warnings/Precautions

Concerns related to adverse effects:

• Angina: Discontinue if symptoms of angina occur or worsen.

• Floppy iris syndrome: Intraoperative floppy iris syndrome has been observed in cataract surgery patients who were on or were previously treated with alpha1-blockers; causality has not been established and there appears to be no benefit in discontinuing alpha-blocker therapy prior to surgery.

• Orthostatic hypotension/syncope: Can cause significant orthostatic hypotension and syncope, especially with first dose; anticipate a similar effect if therapy is interrupted for a few days, if dosage is rapidly increased, or if another antihypertensive drug (particularly vasodilators) or a PDE-5 inhibitor is introduced. Patients should be cautioned about performing hazardous tasks when starting new therapy or adjusting dosage upward.

Disease-related concerns:

• Hepatic impairment: Use with caution in patients with mild-to-moderate hepatic impairment; not recommended in severe dysfunction.

• Prostate cancer: Rule out prostatic carcinoma before beginning therapy.

Special populations:

• Elderly: May be inappropriate in this age group due to potential for dry mouth, hypotension, and urinary problems (Beers Criteria).

Dosage form specific issues:

• Extended release formulation: Consists of drug within a nondeformable matrix; following drug release/absorption, the matrix/shell is expelled in the stool. The use of nondeformable products in patients with known stricture/narrowing of the GI tract has been associated with symptoms of obstruction. Use caution in patients with increased GI retention (eg, chronic constipation) as doxazosin exposure may be increased. Not indicated for use in women or for the treatment of hypertension.