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Terazosin

Pronunciation

Pronunciation

(ter AY zoe sin)

Index Terms

  • Hytrin

Dosage Forms

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

Capsule, Oral:

Generic: 1 mg, 2 mg, 5 mg, 10 mg

Pharmacologic Category

  • Alpha1 Blocker
  • Antihypertensive

Pharmacology

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

Absorption

Rapid and complete

Metabolism

Hepatic; minimal first-pass

Excretion

Feces (~60%, ~20% as unchanged drug); urine (~40%, ~10% as unchanged drug)

Onset of Action

Antihypertensive effect: 15 minutes; Peak effect: Antihypertensive effect: 2 to 3 hours

Time to Peak

Plasma: ~1 hour; delayed ~40 minutes with food

Duration of Action

Antihypertensive effect: 24 hours

Half-Life Elimination

~12 hours

Protein Binding

90% to 94%

Special Populations: Elderly

Plasma clearance was decreased by 31.7% and half-life was 14 hours in patients ≥70 years.

Use: Labeled Indications

Benign prostatic hyperplasia: Treatment of symptomatic benign prostatic hyperplasia (BPH)

Hypertension: Management of hypertension (monotherapy or in combination with other antihypertensives).

Note: The 2014 guideline for the management of high blood pressure in adults (Eighth Joint National Committee [JNC 8]) does not recommend the use of terazosin in the treatment of hypertension (JNC8 [James, 2013]).

Off Label Uses

Pediatric hypertension

Based on the National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents, terazosin given to children for hypertension is an effective and recommended treatment option in the management of this condition.

Ureteral calculi (distal)

Use of alpha-1 adrenergic blockers, including terazosin, for treating ureteral calculi is recommended by US and European guidelines and is supported by data from meta-analyses as well as numerous controlled trials. Tamsulosin has the most data, but terazosin has demonstrated efficacy in facilitating expulsion of ureteral stones (less than 10 mm) as medical therapy alone or as an adjunct to shock wave lithotripsy. Some trials indicate a class effect of alpha-1 adrenergic blockers, with tamsulosin reported to be equally effective as terazosin, doxazosin, and alfuzosin.

Contraindications

Hypersensitivity to terazosin or any component of the formulation

Dosing: Adult

Note: If terazosin is discontinued for several days or longer, consider beginning with initial dose and retitrate as needed.

Benign prostatic hyperplasia: Oral: Initial: 1 mg at bedtime; thereafter, titrate upwards, if needed, over several weeks, balancing therapeutic benefit with terazosin-induced postural hypotension; most patients require 10 mg once daily; if no response after 4 to 6 weeks of 10 mg/day, may increase to 20 mg/day (maximum: 20 mg/day).

Hypertension: Oral: Initial: 1 mg at bedtime; slowly increase dose to achieve desired blood pressure, up to 20 mg/day; usual dosage range (ASH/ISH [Weber 2014]: 1 to 2 mg daily. Note: Daily dosage may be divided and given as a twice-daily regimen if response is diminished at 24 hours and hypotension is observed at 2 to 4 hours following a dose.

Ureteral calculi (distal) (off-label use): Oral: 2 to 5 mg at bedtime for up to 2 weeks or until stone expulsion; may be used as adjunctive therapy to shock wave lithotripsy (Gurbuz 2011; Wang 2009).

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: Pediatric

Hypertension (off-label use): Children and Adolescents: Oral: Initial: 1 mg once daily typically administered at bedtime; slowly increase dose to achieve desired blood pressure as tolerated; maximum daily dose: 20 mg/day (NHBPEP 2004; NHLBI 2011).

Dosing: Renal Impairment

No dosage adjustment necessary.

Hemodialysis: 10% dialyzable; supplemental dose not necessary.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling.

Administration

Administer at the same time each day.

Storage

Store at 20°C to 25°C (68°F to 77°F); protect from light and moisture.

Drug Interactions

Alpha-/Beta-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha-/Beta-Agonists. Similarly, Alpha-/Beta-Agonists may antagonize Alpha1-Blocker vasodilation. Monitor therapy

Alpha1-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha1-Agonists. Similarly, Alpha1-Agonists may antagonize Alpha1-Blocker vasodilation. Monitor therapy

Alpha1-Blockers: May enhance the antihypertensive effect of other Alpha1-Blockers. Avoid combination

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Beta-Blockers: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. The risk associated with ophthalmic products is probably less than systemic products. Exceptions: Levobunolol; Metipranolol. Monitor therapy

Brigatinib: May diminish the antihypertensive effect of Antihypertensive Agents. Brigatinib may enhance the bradycardic effect of Antihypertensive Agents. Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Calcium Channel Blockers: Alpha1-Blockers may enhance the hypotensive effect of Calcium Channel Blockers. Monitor therapy

Dapoxetine: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Levodopa: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. Monitor therapy

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Pholcodine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Pholcodine. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Alpha1-Blockers. Management: Ensure patient is stable on one agent prior to initiating the other, and always initiate combination using the lowest possible dose of the drug being added. When tadalafil is used for treatment of BPH, concurrent alpha 1-blockers are not recommended. Consider therapy modification

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Rilmenidine: Alpha1-Blockers may enhance the hypotensive effect of Rilmenidine. Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Adverse Reactions

>10%:

Central nervous system: Dizziness (9% to 19%), myasthenia (7% to 11%)

1% to 10%:

Cardiovascular: Peripheral edema (1% to 6%), orthostatic hypotension (1% to 4%), palpitations (≤4%), tachycardia (≤2%), syncope (≤1%)

Central nervous system: Drowsiness (4% to 5%), paresthesia (≤3%), vertigo (1%)

Endocrine & metabolic: Decreased libido (≤1%), weight gain (≤1%)

Gastrointestinal: Nausea (2% to 4%)

Genitourinary: Impotence (≤2%)

Neuromuscular & skeletal: Limb pain (≤4%), back pain (≤2%)

Ophthalmic: Blurred vision (≤2%)

Respiratory: Nasal congestion (2% to 6%), dyspnea (2% to 3%), sinusitis (≤3%)

<1% (Limited to important or life-threatening): Abdominal pain, anaphylaxis, anxiety, arthralgia, arthritis, arthropathy, atrial fibrillation, bronchitis, cardiac arrhythmia, chest pain, conjunctivitis, constipation, cough, diaphoresis, diarrhea, dyspepsia, epistaxis, facial edema, fever, flatulence, flu-like symptoms, gout, hypersensitivity reaction, insomnia, intraoperative floppy iris syndrome (IFIS), myalgia, neck pain, pharyngitis, polyuria, priapism, pruritus, rhinitis, shoulder pain, skin rash, thrombocytopenia, tinnitus, urinary incontinence, urinary tract infection, vasodilatation, visual disturbance, vomiting, xerostomia

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery or driving).

• Floppy iris syndrome: Intraoperative floppy iris syndrome has been observed in cataract surgery patients who were on or were previously treated with alpha1-blockers; there appears to be no benefit in discontinuing alpha-blocker therapy prior to surgery. May require modifications to surgical technique.

• Orthostatic hypotension/syncope: May cause significant orthostatic hypotension and syncope, especially with first dose or first few days of therapy; 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.

• Priapism: Priapism has been associated with use (rarely); seek immediate medical assistance for erections lasting longer than 4 hours.

Disease-related concerns:

• Heart failure: In a scientific statement from the American Heart Association, terazosin has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: moderate) (AHA [Page 2016]).

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Other warning/precautions:

• Appropriate use: BPH: Rule out prostatic carcinoma before beginning therapy (many symptoms of BPH and prostate cancer are similar).

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

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have not been observed in animal studies. Untreated chronic maternal hypertension is associated with adverse events in the fetus, infant, and mother. If treatment for hypertension during pregnancy is needed, other agents are generally preferred (ACOG 2013).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience fatigue, rhinitis, rhinorrhea, nausea, loss of strength and energy, or headache. Have patient report immediately to prescriber severe dizziness, passing out, vision changes, sexual dysfunction, tachycardia, arrhythmia, swelling of arms or legs, or priapism (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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