terazosin (Rx)

Brand and Other Names:Hytrin
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

capsule

  • 1mg
  • 2mg
  • 5mg
  • 10mg

Benign Prostate Hyperplasia

Initial: 1 mg PO qHS

May gradually increase to 5 mg PO qHS; up to 20 mg/day beneficial for some

Dosing considerations

  • Give first dose and subsequent increases at bedtime to avoid syncope
  • May take with food

Hypertension

Initial: 1 mg PO qHS

Maintenance: 1-5 mg/day or q12hr; may increase to ≤20 mg/day

Dosing considerations

  • Give first dose and subsequent increases at bedtime to avoid syncope
  • May take with food

Dosing Modifications

Hepatic impairment: Use with caution

Dosage Forms & Strengths

capsule

  • 1mg
  • 2mg
  • 5mg
  • 10mg

Hypertension (Off-label)

1 mg/day PO; increase dose gradually as necessary; up to maximum of 20 mg/day

Hypertension

Initial: 0.5 mg PO qHS and titrate to response

Dosing considerations

Avoid use for hypertension; high risk of orthostatic hypotension (Beers criteria)

May cause significant orthostatic hypotension and syncope

Lower initial doses than those used for nongeriatric adults, as well as gradual adjustments, are recommended for hypertension

Give first dose and subsequent increases at bedtime to avoid syncope

Adverse effects such as dry mouth and urinary complications can be bothersome in the elderly

May take with food

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Interactions

Interaction Checker

and terazosin

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            Adverse Effects

            >10%

            Dizziness (10-20%)

            Asthenia (2-13%)

            1-10%

            Hypotension (3-7%)

            Rhinitis/nasal congestion (2-6%)

            Lightheadedness (3-5%)

            Somnolence (3-5%)

            Palpitation (4%)

            Nausea (2-4%)

            Edema (3%)

            Sinusitis (3%)

            Dyspnea (2-3%)

            Fatigue (2.5%)

            Headache (2.5%)

            Back pain (2.4%)

            Flulike syndrome (2.4%)

            Tachycardia (2%)

            Amblyopia (1-2%)

            Blurred vision (1-2%)

            Impotence (1-2%)

            Syncope (1%)

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            Warnings

            Contraindications

            Hypersensitivity to terazosin, other quinazolines

            Cautions

            Carcinoma of the prostate and BPH cause many of the same symptoms; these two diseases frequently co-exist; patients thought to have BPH should be examined prior to starting therapy to rule out presence of carcinoma of the prostate

            Therapy can cause marked lowering of blood pressure, especially postural hypotension, and syncope in association with first dose or first few days of therapy; a similar effect can be anticipated if therapy is interrupted for several days and then restarted; to decrease likelihood of syncope or excessive hypotension, treatment should always be initiated at a low dose (1 mg) and increased slowly; additional antihypertensive agents should be added with caution; patient should be cautioned to avoid situations, such as driving or hazardous tasks, where injury could result should syncope occur during initiation of therapy

            If syncope occurs, the patient should be placed in a recumbent position and treated supportively as necessary; there is evidence that orthostatic effect is greater, even in chronic use, shortly after dosing; the risk of the events is greatest during initial seven days of treatment, but continues at all time intervals

            While syncope is the most severe orthostatic effect, other symptoms of lowered blood pressure, such as dizziness, lightheadedness and palpitations, are more common; patients with occupations in which such events represent potential problems should be treated with particular caution

            May cause CNS depression, which may impair physical or mental abilities; use caution when performing tasks that may require mental alertness, including driving or operating heavy machinery

            May exacerbate heart failure

            Concomitant administration with PDE-5 inhibitor (eg, sildenafil) can result in additive blood pressure-lowering effects and symptomatic hypotension; initiate PDE-5 inhibitor therapy at lowest dose

            Risk of priapism (rare); because this condition can lead to permanent impotence if not promptly treated, patients must be advised about seriousness of the condition

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            Pregnancy & Lactation

            Pregnancy category: C

            Lactation: Not known if excreted into breast milk; use caution

            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.

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            Pharmacology

            Mechanism of Action

            Blocks postsynaptic alpha-1 receptor; alpha blockade causes arterial and venous dilation

            Selective agents cause less tachycardia than do nonselective agents

            Absorption

            Bioavailability: 90%

            Onset (hypertension): 3 hr

            Onset (benign prostate hyperplasia): 2 weeks

            Duration: 24 hr

            Peak response (benign prostate hyperplasia): 4-6 weeks

            Peak plasma time: 1 hr

            Distribution

            Protein bound: 90-94%

            Vd: 25-30 L

            Metabolism

            Metabolized extensively via hydrolysis, O-demethylation, and N-dealkylation in liver

            Metabolites: 6- and 7-O-demethyl terazosin, piperazine derivative, diamine metabolite

            Elimination

            Half-life: 9-12 hr

            Renal clearance: 9-12.5 mL/min

            Excretion: Feces (55-60%); urine (40%)

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            Formulary

            FormularyPatient Discounts

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            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.
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            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
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            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.