Terazosin

Pronunciation

(ter AY zoe sin)

U.S. Brand Names

Hytrin®

Generic Available

Yes

Canadian Brand Names

Alti-Terazosin; Apo-Terazosin®; Hytrin®; Novo-Terazosin; Nu-Terazosin; PMS-Terazosin

Use

Management of mild to moderate hypertension; alone or in combination with other agents such as diuretics or beta-blockers; benign prostate hyperplasia (BPH)

Pregnancy Risk Factor

Lactation

Excretion in breast milk unknown

Contraindications

Hypersensitivity to quinazolines (doxazosin, prazosin, terazosin) or any component of the formulation; concurrent use with phosphodiesterase-5 (PDE-5) inhibitors including sildenafil (>25 mg), tadalafil, or vardenafil

Warnings/Precautions

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

Adverse Reactions

Asthenia, postural hypotension, dizziness, somnolence, nasal congestion/rhinitis, and impotence were the only events noted in clinical trials to occur at a frequency significantly greater than placebo (p <0.05).

>10%:

Central nervous system: Dizziness, headache

Neuromuscular & skeletal: Muscle weakness

1% to 10%:

Cardiovascular: Edema, palpitation, chest pain, peripheral edema (3%), orthostatic hypotension (3% to 4%), tachycardia

Central nervous system: Fatigue, nervousness, drowsiness

Gastrointestinal: Dry mouth

Genitourinary: Urinary incontinence

Ocular: Blurred vision

Respiratory: Dyspnea, nasal congestion

<1% (Limited to important or life-threatening): Sexual dysfunction, syncope (0.8%)

Postmarketing and/or case reports: Allergic reactions, anaphylaxis, atrial fibrillation, priapism, thrombocytopenia

Overdosage/Toxicology

Symptoms of overdose include hypotension, drowsiness, and shock. Treatment is supportive and symptomatic.

Drug Interactions

ACE inhibitors: Hypotensive effect may be increased.

Beta-blockers: Hypotensive effect may be increased.

Calcium channel blockers: Hypotensive effect may be increased.

NSAIDs may reduce antihypertensive efficacy.

Sildenafil, tadalafil, vardenafil: Blood pressure-lowering effects are additive. Use of tadalafil or vardenafil is contraindicated by the manufacturer. Use sildenafil with extreme caution (dose 25 mg).

Ethanol/Nutrition/Herb Interactions

Herb/Nutraceutical: Avoid dong quai if using for hypertension (has estrogenic activity). Avoid ephedra, yohimbe, ginseng (may worsen hypertension). Avoid saw palmetto. Avoid garlic (may have increased antihypertensive effect).

Mechanism of Action

Alpha1-specific blocking agent with minimal alpha2 effects; this allows peripheral postsynaptic blockade, with the resultant decrease in arterial tone, while preserving the negative feedback loop which is mediated by the peripheral presynaptic alpha2-receptors; terazosin relaxes the smooth muscle of the bladder neck, thus reducing bladder outlet obstruction

Pharmacodynamics/Kinetics

Onset of action: 1-2 hours

Absorption: Rapid

Protein binding: 90% to 95%

Metabolism: Extensively hepatic

Half-life elimination: 9.2-12 hours

Time to peak, serum: ~1 hour

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

Dosage

Oral: Adults:

Hypertension: Initial: 1 mg at bedtime; slowly increase dose to achieve desired blood pressure, up to 20 mg/day; usual dose range (JNC 7): 1-20 mg once daily

Dosage reduction may be needed when adding a diuretic or other antihypertensive agent; if drug is discontinued for greater than several days, consider beginning with initial dose and retitrate as needed; dosage may be given on a twice daily regimen if response is diminished at 24 hours and hypotensive is observed at 2-4 hours following a dose

Benign prostatic hyperplasia: Initial: 1 mg at bedtime, increasing as needed; most patients require 10 mg day; if no response after 4-6 weeks of 10 mg/day, may increase to 20 mg/day

Monitoring Parameters

Standing and sitting/supine blood pressure, especially following the initial dose at 2-4 hours following the dose and thereafter at the trough point to ensure adequate control throughout the dosing interval; urinary symptoms

Dietary Considerations

May be taken without regard to meals at the same time each day.

Patient Education

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Take as directed; at bedtime. Do not skip dose or discontinue without consulting prescriber. Follow recommended diet and exercise program. 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); dry mouth or nausea (frequent mouth care or sucking lozenges may help); urinary incontinence (void before taking medication); or sexual dysfunction (reversible, may resolve with continued use). Report altered CNS status (eg, fatigue, lethargy, confusion, nervousness); 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; respiratory difficulty; muscle weakness; or other persistent side effects. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Consult prescriber if breast-feeding.

Nursing Implications

Syncope may occur usually within 90 minutes of the initial dose; administer initial dose at bedtime

Monitor blood pressure, standing and sitting/supine

Cardiovascular Considerations

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

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation).

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

Dizziness is common; may cause drowsiness or nervousness; may rarely cause insomnia or depression

Mental Health: Effects on Psychiatric Treatment

None reported

Dosage Forms

Capsule (Hytrin®): 1 mg, 2 mg, 5 mg, 10 mg

Tablet: 1 mg, 2 mg, 5 mg, 10 mg

References

Chobanian AV, Bakris GL, Black HR, et al, "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report," JAMA , 2003, 289(19):2560-71.

International Brand Names

Adecur® (BR, MX); Alti-Terazosin (CA); Apo-Terazosin® (CA); Benaprost® (AR); Benph® (IE); Blavin® (AR); Cloridrato de Terazosina® (BR); Deflox® (ES); Dysalfa® (FR); Eglidon® (AR); Ezosina® (IT); Flotrin® (DE); Flumarc® (AR); Fosfomik® (AR); Gerioformin® (AR); Heitrin® (DE); Hitrin® (CR, GT, HN, PA, SV); Hyron® (HU); Hytracin® (JP); Hytrin® (AU, BD, BE, BR, CA, CL, CO, CZ, GB, HK, HU, ID, IE, IL, IN, LU, MX, NL, PL, PT, RO, SG, TH, TR, ZA); Hytrin BPH® (CH, GB, NZ); Hytrine® (FR); Hytrinex® (SE); Ibiprovir® (IT); Isontyn® (AR); Itrin® (IT); Kornam® (CZ, HU, PL, RU, SI); Magnurol® (ES); Novo-Terazosin (CA); Nu-Terazosin (CA); Olyster® (IN); PMS-Terazosin (CA); Prostatil® (IT); Setegis® (HU, PL); Sinalfa® (DK, NO, SE); Sutif® (ES); Tazusin® (ES); Terablock® (DE); Terafluss® (IT); Teranar® (DE); Teraprost® (IT); Terasin® (DO, EC); Tera TAD® (DE); Teraumon® (ES); Terazid® (DE); Terazoflo® (DE); Terazosin 1A Pharma® (DE); Terazosina Alter® (ES); Terazosin AbZ® (DE); Terazosina Kern® (ES); Terazosin AL® (DE); Terazosina Qualix® (ES); Terazosin Arcana® (AT); Terazosina Rubio® (ES); Terazosina Teva® (IT); Terazosin AWD® (DE); Terazosin AZU® (DE); Terazosin BASICS® (DE); Terazosin beta® (DE); Terazosin® (GB, RO); Terazosin Hexal® (DE); Terazosin NM Pharma® (SE); Terazosin-ratiopharm® (DE); Terazosin Sandoz® (DE); Terazosin Stada® (DE); Terazosin von ct® (DE); Terenar® (DE); Tezosyn® (DO); Tructum® (CO); Unoprost® (IT); Urodie® (IT); Uroflo® (AT); Uro-Hytrin® (BE); Urozosin® (DE); Vasomet® (JP); Vicard® (AT); Zayasel® (ES)

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