Skip to Content

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

Serum: ~1 hour

Duration of Action

Antihypertensive effect: 24 hours

Half-Life Elimination

~12 hours

Protein Binding

90% to 95%

Special Populations: Elderly

After oral administration, plasma Cl was decreased 31.7% in patients older than 70 yr of age vs patients 20 to 39 yr of age.

Use: Labeled Indications

Hypertension: Management of mild-to-moderate hypertension; alone or in combination with other agents such as diuretics or beta-blockers

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]).

Benign prostate hyperplasia: Benign prostate hyperplasia (BPH)

Use: Unlabeled

Pediatric hypertension

Contraindications

Hypersensitivity to terazosin or any component of the formulation

Dosing: Adult

Note: If drug is discontinued for greater than several days, consider beginning with initial dose and retitrate as needed.

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]: 1-2 mg daily. Note: Dosage may be given on a twice daily regimen if response is diminished at 24 hours and hypotension is observed at 2-4 hours following a dose.

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 day; if no response after 4-6 weeks of 10 mg/day, may increase to 20 mg/day

Dosage adjustment with concurrent medication:

Concurrent use with a diuretic or other antihypertensive agent (especially verapamil): Dosage reduction may be needed when adding

Concurrent use with PDE-5 inhibitors: Initiate PDE-5 inhibitor therapy at the lowest dose due to additive orthostatic and blood pressure lowering effects

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): Oral: Initial: 1 mg once daily; gradually increase dose as necessary, up to maximum of 20 mg/day

Dosing: Renal Impairment

No dosage adjustment necessary.

Hemodialysis: No supplemental dose necessary.

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer’s labeling.

Administration

Administer without regard to meals at the same time each day.

Dietary Considerations

May be taken without regard to meals 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

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

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

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

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

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

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

Adverse Reactions

>10%:

Central nervous system: Dizziness (9% to 19%)

Neuromuscular & skeletal: Muscle weakness (7% to 11%)

1% to 10%:

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

Central nervous system: Somnolence (4% to 5%), vertigo (1%)

Gastrointestinal: Nausea (2% to 4%), weight gain (≤1%)

Genitourinary: Impotence (≤2%), libido decreased (≤1%)

Neuromuscular & skeletal: Extremity pain (≤4%), paresthesia (≤3%), back pain (≤2%)

Ocular: Blurred vision (≤2%)

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

<1% (Limited to important or life-threatening): Abdominal pain, abnormal vision, allergic reactions, anaphylaxis, anxiety, arrhythmia, arthralgia, arthritis, atrial fibrillation, bronchitis, chest pain, conjunctivitis, constipation, cough, diaphoresis, diarrhea, dyspepsia, epistaxis, facial edema, fever, flatulence, flu-like syndrome, gout, insomnia, intraoperative floppy iris syndrome (IFIS), joint disorder, myalgia, neck pain, pharyngitis, polyuria, priapism, pruritus, rash, rhinitis, shoulder pain, thrombocytopenia, tinnitus, urinary incontinence, urinary tract infection, vasodilation, vomiting, xerostomia

Warnings/Precautions

Concerns related to adverse effects:

• Angina: Discontinue if symptoms of angina occur or worsen.

• Floppy iris syndrome: Intraoperative floppy iris syndrome has been observed in cataract surgery patients who were on or were previously treated with alpha1-blockers; causality has not been established and there appears to be no benefit in discontinuing alpha-blocker therapy prior to surgery.

• Orthostatic hypotension/syncope: May cause significant orthostatic hypotension and syncope, especially with first dose; 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. Patients should be cautioned about performing hazardous tasks when starting new therapy or adjusting dosage upward.

• Priapism: Priapism has been associated with use (rarely).

Disease-related concerns:

• Prostate cancer: It is recommended to rule out prostatic carcinoma before beginning therapy.

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

Teratogenic effects have not been observed in animal studies. Decreased fetal weight and increased risk of fetal mortality were noted in some animal reproduction studies. There are no adequate and well-controlled studies in pregnant women. Use only if benefit outweighs risk.

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, dyspepsia, asthenia, or headache. Have patient report immediately to prescriber severe dizziness, syncope, vision changes, sexual dysfunction, tachycardia, arrhythmia, edema of extremities, 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 healthcare 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.

Hide