No

Alpha₁ Blockers

Treatment of hypertension alone or in conjunction with diuretics, cardiac glycosides, ACE inhibitors, or calcium antagonists (particularly appropriate for those with hypertension and other cardiovascular risk factors such as hypercholesterolemia and diabetes mellitus); treatment of urinary outflow obstruction and/or obstructive and irritative symptoms associated with benign prostatic hyperplasia (particularly useful in patients with troublesome symptoms who are unable or unwilling to undergo invasive procedures, but who require rapid symptomatic relief)

C

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

Can cause significant orthostatic hypotension and syncope, especially with first dose. Prostate cancer should be ruled out before starting for BPH. May need dosage adjustment in severe hepatic dysfunction. Anticipate a similar effect if therapy is interrupted for a few days, if dosage is rapidly increased, or if another antihypertensive drug is introduced.

>10%: Central nervous system: Dizziness (16% to 19%), headache (10% to 14%)

1% to 10%:

Cardiovascular: Orthostatic hypotension (dose-related; 0.3% up to 10%), edema (2.7% to 4%), hypotension (1.7%), palpitation (1.2% to 2%), chest pain (1.2% to 2%), arrhythmia (1%), syncope (2%), flushing (1%)

Central nervous system: Fatigue (8% to 12%), somnolence (3% to 5%), nervousness (2%), pain (2%), vertigo (2%), insomnia (1% to 1.2%), anxiety (1.1%), paresthesia (1%), movement disorder (1%), ataxia (1%), hypertonia (1%), depression (1%), weakness (1%)

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

Endocrine & metabolic: Sexual dysfunction (2%)

Gastrointestinal: Abdominal pain (2.4%), diarrhea (2% to 2.3%), dyspepsia (1% to 1.7%), nausea (1.5% to 3%) xerostomia (1.4% to 2%), constipation (1%), flatulence (1%)

Genitourinary: Urinary tract infection (1.4%), impotence (1.1%), polyuria (2%), incontinence (1%)

Neuromuscular & skeletal: Back pain (1.8%), arthritis (1%), muscle weakness (1%), myalgia (1%), muscle cramps (1%)

Ocular: Abnormal vision (1.4% to 2%), conjunctivitis (1%)

Otic: Tinnitus (1%)

Respiratory: Rhinitis (3%), dyspnea (1% to 2.6%), respiratory disorder (1.1%), epistaxis (1%)

Miscellaneous: Flu-like syndrome (1.1%), increased sweating (1.1%)

<1% (Limited to important or life-threatening symptoms): Tachycardia, bradycardia, peripheral ischemia, syncope, hypoesthesia, increased sweating, agitation, weight gain, angina, myocardial infarction, stroke, pallor, thirst, gout, hypokalemia, lymphadenopathy, purpura, breast pain, alopecia, dry skin, eczema, paresis, twitching, confusion, migraine, impaired concentration, paranoia, amnesia, emotional lability, abnormal thinking, depersonalization, parosmia, earache, taste perversion, photophobia, abnormal lacrimation, increased appetite, anorexia, fecal incontinence, gastroenteritis, bronchospasm, sinusitis, coughing, pharyngitis, renal calculus, hot flashes, infection, fever, rigors, weight loss

Case reports: Leukopenia, cataplexy, enuresis, systemic lupus erythematosus

Symptoms of overdose include severe hypotension, drowsiness, tachycardia

Hypotension usually responds to I.V. fluids, Trendelenburg positioning, or parenteral vasoconstrictor; treatment is primarily supportive and symptomatic.

NSAIDs may reduce antihypertensive efficacy.

ACE inhibitors: Hypotensive effect may be increased.

Beta-blockers: Hypotensive effect may be increased.

Calcium channel blockers: Hypotensive effect may be increased.

Competitively inhibits postsynaptic alpha-adrenergic receptors which results in vasodilation of veins and arterioles and a decrease in total peripheral resistance and blood pressure; approximately 50% as potent on a weight by weight basis as prazosin

Increased age does not significantly affect pharmacokinetics of doxazosin

Duration: >24 hours

Half-life: 22 hours

Time to peak serum concentration: 2-3 hours

Oral:

Hypertension: Maximum dose: 16 mg/day

BPH: Maximum dose: 8 mg/day.

Elderly: Initial: 0.5 mg once daily

Blood pressure, standing and sitting/supine

Increased urinary VMA 17%, norepinephrine metabolite 42%

Doxazosin can be used alone or in combination as an antihypertensive. Patients with BPH may derive an extra benefit from therapy.

Dizziness is common; may cause anxiety, nervousness, or sedation; rarely may cause depression

Psychotropics may potentiate the hypotensive effects of doxazosin

No information available to require special precautions

No effects or complications reported

Take as directed, at bedtime. Do not skip dose or discontinue without consulting prescriber. Follow recommended diet and exercise program. Do not use OTC medications which may affect blood pressure (eg, cough or cold remedies, diet pills, stay-awake medications) without consulting prescriber. This medication may cause drowsiness, dizziness, or impaired judgment (use caution when driving or engaging in tasks that require alertness until response to drug is known); postural hypotension (use caution when rising from sitting or lying position or when climbing stairs); or dry mouth or nausea (frequent mouth care or sucking lozenges may help). Report increased nervousness or depression; sudden weight gain (weigh yourself in the same clothes at the same time of day once a week); unusual or persistent swelling of ankles, feet, or extremities; palpitations or rapid heartbeat; muscle weakness, fatigue, or pain; or other persistent side effects. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

Syncope may occur usually within 90 minutes of the initial dose

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

Boston D and Collins C, "Safety, Efficacy, and Lipid Profile of Doxazosin at a VA Medical Center," Hosp Formul, 1995, 30(4):233-6.

Carlson RV, Bailey RR, Begg EJ, et al, "Pharmacokinetics and Effect on Blood Pressure of Doxazosin in Normal Subjects and Patients With Renal Failure," Clin Pharmacol Ther, 1986, 40(5):561-6.

Cubeddu LX, Fuenmayor N, Caplan N, et al, "Clinical Pharmacology of Doxazosin in Patients With Essential Hypertension," Clin Pharmacol Ther, 1987, 41(4):439-49.