doxazosin (Rx)

Brand and Other Names:Cardura, Cardura XL
  • Print

Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 1mg
  • 2mg
  • 4mg
  • 8mg

tablet, extended release

  • 4mg
  • 8mg
more...

Hypertension

1 mg PO qDay in AM or PM; may titrate by doubling daily dose up to 16 mg qDay based on blood pressure response; usual dosage range is 1-2 mg qDay; if therapy is discontinued for several days, initiate dose at 1 mg qDay and titrate using initial dosing regimen

Extended release: Not indicated for hypertension

Benign Prostatic Hyperplasia

Immediate release: 1 mg PO qDay; may titrate by doubling daily dose at 1-2 week intervals to maximum 8 mg/day

If therapy is discontinued for several days, initiate dose at 1 mg qDay and titrate using initial dosing regimen

Extended release: 4 mg PO qDay; may titrate based on response and tolerability every 3-4 weeks to 8 mg PO qDay

If therapy is discontinued for several days, initiate dose at 1 mg qDay and titrate using initial dosing regimen

Dosing Modifications

Hepatic impairment: Use with caution in mild-to-moderate hepatic dysfunction; do not use in severe impairment

Renal impairment: Labeling from manufacturer does not provide dosage adjustment information

Dosing Considerations

Give first dose and increase at bedtime to avoid syncope

Dosage Forms & Strengths

tablet

  • 1mg
  • 2mg
  • 4mg
  • 8mg
more...

Hypertension (Off-label)

Immediate release: 1-4 mg PO once daily in AM or PM

Hypertension

Avoid use for hypertension; high risk of orthostatic hypotension (Beers criteria); if used, lower initial dosages and gradual adjustments are recommended

Immediate release: 0.5-16 mg PO once daily in AM or PM

Extended release: Not indicated for hypertension

Benign Prostatic Hyperplasia

Immediate release: 1-8 mg/day PO

Extended release: 4 mg/day PO initially at breakfast; may be increased to no more than 8 mg/day PO

Next:

Interactions

Interaction Checker

and doxazosin

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

            All Interactions Sort By:
             activity indicator 
            Previous
            Next:

            Adverse Effects

            >10%

            Dizziness (5-19%)

            Fatigue (8-12%)

            Headache (6-10%)

            1-10%

            Vertigo (7%)

            Upper respiratory tract infection (URTI) (5%)

            Edema (3-4%)

            Rhinitis (3%)

            Dyspnea (1-3%)

            Abdominal pain (2%)

            Hypotension (1-2%)

            Nausea (1-2%)

            Orthostatic hypotension (dose related) (0.3-2%)

            Anxiety (1%)

            Palpitations (1%)

            Postmarketing experience

            Autonomic Nervous System: Priapism

            Cardiovascular System: Cerebrovascular accidents, dizziness postural, myocardial infarction

            Central and Peripheral Nervous System: Hypoesthesia, paresthesia

            Endocrine System: Gynecomastia

            Gastrointestinal System: Gastrointestinal obstruction, vomiting

            General Body System: Fatigue, hot flushes, malaise

            Heart Rate/Rhythm: Bradycardia, cardiac arrhythmias

            Hematopoietic: Leukopenia, purpura, thrombocytopenia

            Liver/Biliary System: Abnormal liver function tests, hepatitis, hepatitis cholestatic, jaundice

            Musculoskeletal System: Muscle cramps, muscle weakness

            Psychiatric: Agitation, anorexia, nervousness

            Respiratory System: Bronchospasm aggravated

            Skin Disorders: Alopecia, urticaria, skin rash, pruritus

            Special Senses: Blurred vision, intraoperative Floppy Iris Syndrome

            Urinary System: Hematuria, micturition disorder, micturition frequency, nocturia, polyuria

            Previous
            Next:

            Warnings

            Contraindications

            Hypersensitivity to doxazosin or other quinazolines

            Cautions

            Use with caution in liver disease or recent cerebrovascular accident (CVA)

            Rule out prostate cancer before initiating therapy

            May cause first-dose syncope or sudden loss of consciousness

            Risk of orthostatic hypotension (dose dependent)

            Potential for hypotension, dry mouth, and urinary complications in elderly

            Priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation) rarely reported (probably less frequently than once in every several thousand patients), with alpha-1 antagonists, including doxazosin; because condition can lead to permanent impotence if not promptly treated, patients must be advised about seriousness of condition

            Concomitant use of other antihypertensives (additive hypotensive effects)

            Extended-release form not indicated for hypertension

            Concomitant administration of immediate-release form with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension

            May increase the risk of heart failure by exacerbating underlying myocardial dysfunction by β1Receptor stimulation with increases in renin and aldosterone

            May cause CNS depression, which may impair ability to operate heavy machinery and performing tasks that require mental alertness

            Allergic reactions, including urticaria, rash, angioedema, pruritus, and respiratory symptoms may occur

            Intraoperative floppy iris syndrome reported in cataract surgery patients who received alph1-blocker therapy; discontinuing alpha-blocker therapy prior to surgery does not appear to be of benefit

            Decreases in white blood cells (WBC) and neutrophil count reported; WBC and neutrophil counts returned to normal following discontinuation of therapy

            Previous
            Next:

            Pregnancy & Lactation

            Pregnancy

            Not indicated for use in females or for the treatment of hypertension; the limited available data in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriage; no adverse developmental outcomes were observed in animal reproduction studies with oral administration to pregnant rats and rabbits at doses of up to 10 and 4 times, respectively, the 12 mg/day recommended dose; postnatal development was delayed in rats at a dose of 8 times the 12 mg/day recommended dose

            Lactation

            Present in human milk; there is no information on effects on breastfed infant or effects on milk production

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

            more...
            Previous
            Next:

            Pharmacology

            Mechanism of Action

            Hypertension: Blocks postsynaptic alpha1 receptors; alpha blockade causes arterial, arteriolar, and venous dilation; decreases total peripheral resistance and blood pressure

            Benign prostatic hyperplasia (BPH): Blocks alpha1 receptors in prostatic stromal and bladder tissues; reduces sympathetic tone-induced urethral stricture responsible for BPH symptoms

            Absorption

            Bioavailability: Immediate release, 65%; extended release, 54-59%

            Onset (antihypertensive response): Peak, 4-8 hr

            Onset (BPH response): Initial, 2 wk; peak, 4-6 weeks

            Duration: 24 hr

            Peak plasma time: 2-3 hr

            Distribution

            Protein bound: 99%

            Vd: 1-3.4 L/kg

            Metabolism

            Metabolized extensively in liver

            Metabolites: 6- and 7-O-demethyl metabolites, 6'- and 7'-hydroxy metabolites, other minor metabolites (activity unknown)

            Elimination

            Half-life: Immediate release, 22 hr; extended release, 15-19 hr

            Dialyzable: HD, no

            Total body clearance: 83-140 mL/min

            Excretion: Feces (65%), urine (0.6-9%)

            Previous
            Next:

            Images

            Previous
            Next:

            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
            Additional Offers
            Email to Patient

            From:

            To:

            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Email Forms to Patient

            From:

            To:

            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Previous
            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.