Terazosin

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

Pharmacology

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

Pharmacokinetics/Pharmacodynamics

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%

Use in Specific Populations

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. Note: Alpha blockers are not recommended as first line therapy (ACC/AHA [Whelton 2017]).

Use: Off Label

Ureteral calculi expulsionbyes

Use of alpha-1 adrenergic blockers, including terazosin, for treating ureteral calculi is supported by data from a meta-analysis as well as numerous controlled trials. Tamsulosin has the most data, but terazosin has also demonstrated efficacy in facilitating expulsion of ureteral stones (<10 mm) as medical therapy alone or as an adjunct to shock wave lithotripsy and uteroscopy. Some trials indicate a class effect of alpha-1 adrenergic blockers, with terazosin reported to be equally effective as tamsulosin, doxazosin, and alfuzosin Campshroer 2018, Gurbuz 2011, Wang 2009.

American Urological Association/Endourological Society guidelines and European Association of Urology guidelines recommend use of alpha-1 blockers, including terazosin, for treating ureteral calculi

Contraindications

Hypersensitivity to terazosin or any component of the formulation

Dosage and Administration

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 (alternative agent): Oral: Initial: 1 mg once daily; titrate as needed based on patient response up to a dose of 20 mg daily in 1 or 2 divided doses (ACC/AHA [Whelton 2017]). Note: Administration at bedtime may help limit orthostasis.

Ureteral calculi expulsion (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

Avoid use for hypertension treatment (Beers Criteria [AGS 2019]). Refer to adult dosing for other indications.

Dosing: Pediatric

Hypertension: Children and Adolescents: Limited data available: 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). Note: If drug is discontinued for greater than several days, consider beginning with initial dose and retitrate as needed.

Administration

Oral: 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

Bromperidol: Blood Pressure Lowering Agents may enhance the hypotensive effect of Bromperidol. Bromperidol may diminish the hypotensive effect of Blood Pressure Lowering Agents. Avoid combination

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

Dexmethylphenidate: May diminish the therapeutic effect of Antihypertensive Agents. 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-Containing Products: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa-Containing Products. 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 (Nonselective). 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%, postmarketing, and/or case reports: 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, vasodilation, 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

Hypertension: The 2017 Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults (ACC/AHA [Whelton 2017]):

Confirmed hypertension and known CVD or 10-year ASCVD risk ≥10%: Target blood pressure <130/80 mm Hg is recommended

Confirmed hypertension without markers of increased ASCVD risk: Target blood pressure <130/80 mm Hg may be reasonable

Pregnancy

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have been observed in some animal reproduction studies.

Chronic maternal hypertension may increase the risk of birth defects, low birth weight, preterm delivery, stillbirth, and neonatal death. Actual fetal/neonatal risks may be related to duration and severity of maternal hypertension. Untreated hypertension may also increase the risks of adverse maternal outcomes, including gestational diabetes, myocardial infarction, preeclampsia, stroke, and delivery complications (ACOG 203 2019).

Agents other than terazosin are more commonly used to treat hypertension in pregnancy (ACOG 203 2019; ESC [Regitz-Zagrosek 2018]). Females with preexisting hypertension may continue their medication during pregnancy unless contraindications exist (ESC [Regitz-Zagrosek 2018]).

Patient Education

What is this drug used for?

• It is used to treat high blood pressure.
• In men, it is used to treat the signs of an enlarged prostate.
• It may be given to you for other reasons. Talk with the doctor.

Frequently reported side effects of this drug

• Fatigue
• Runny nose
• Nausea
• Loss of strength and energy
• Headache

Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:

• Severe dizziness
• Passing out
• Vision changes
• Fast heartbeat
• Abnormal heartbeat
• Swelling of arms or legs
• Erection that lasts more than 4 hours
• Signs of a significant reaction like 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. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.