(ter AY zoe sin)
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Generic: 1 mg, 2 mg, 5 mg, 10 mg
- Alpha1 Blocker
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
Rapid and complete
Hepatic; minimal first-pass
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
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)
Hypersensitivity to terazosin or any component of the formulation
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
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).
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.
Administer without regard to meals at the same time each day.
May be taken without regard to meals at the same time each day.
Store at 20°C to 25°C (68°F to 77°F); protect from light and moisture.
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
Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy
Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy
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
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).
• Prostate cancer: It is recommended to rule out prostatic carcinoma before beginning therapy.
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
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).
• 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.
More about terazosin
- Other brands: Hytrin