terazosin

Absorption: Well absorbed after oral administration.

Distribution: Unknown.

Metabolism/Excretion: 50% metabolized by the liver. 10% excreted unchanged by the kidneys. 20% excreted unchanged in feces. 40% eliminated in bile.

Half-Life: 12 hr.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET‡	PEAK‡	DURATION‡
PO-hypertension	15 min	6–8 wk	24 hr
PO-BPH	2–6 wk	unknown	unknown

‡After single dose.

‡After multiple oral dosing.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity.

Use Cautiously in:

Dehydration, volume or sodium depletion (↑ risk of hypotension);
Patients undergoing cataract surgery (↑ risk of intraoperative floppy iris syndrome);
OB: Other antihypertensive agents preferred during pregnancy;
Lactation: Safety not established in breastfeeding;
Pedi: Safety and effectiveness not established in children;
Geri: Appears on Beers list. ↑ risk of orthostatic hypotension in older adults. Avoid use for treatment of hypertension in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

CV: first-dose orthostatic hypotension, arrhythmias, chest pain, palpitations, peripheral edema, tachycardia

Derm: pruritus

EENT: nasal congestion, blurred vision, conjunctivitis, intraoperative floppy iris syndrome, sinusitis

GI: nausea, abdominal pain, diarrhea, dry mouth, vomiting

GU: erectile dysfunction, urinary frequency

Metab: weight gain

MS: arthralgia, back pain, extremity pain

Neuro: dizziness, headache, weakness, drowsiness, nervousness, paresthesia

Resp: dyspnea

Misc: fever

Interactions ⬆ ⬇

Drug-drug:

↑risk of hypotension with sildenafil, tadalafil, vardenafil, other antihypertensives, nitrates, or acute ingestion of alcohol.
NSAIDs, sympathomimetics, or estrogens may ↓ effects of antihypertensive therapy.

Route/Dosage ⬆ ⬇

Hypertension

PO (Adults ): 1 mg initially; then slowly ↑ up to 5 mg/day (usual range 1–5 mg/day); may be given as single dose or in 2 divided doses (not to exceed 20 mg/day).

Benign Prostatic Hyperplasia

PO (Adults ): 1 mg at bedtime; may be gradually ↑ up to 5–10 mg/day.

Availability ⬆ ⬇

(Generic available)

Capsules: 1 mg; 2 mg; 5 mg; 10 mg
Tablets: 1 mg; 2 mg; 5 mg; 10 mg

Assessment ⬆ ⬇

Assess for first-dose orthostatic reaction (dizziness, weakness) and syncope. May occur 30 min–2 hr after initial dose and occasionally thereafter. Incidence may be dose related. Volume-depleted or sodium-restricted patients may be more sensitive. Observe patient closely during this period; take precautions to prevent injury. 1st dose may be given at bedtime to minimize this reaction. Geri: Older adults are at high risk of orthostatic hypotension.
- Monitor intake and output ratios and daily weight; assess for edema daily, especially at beginning of therapy.
Hypertension: Monitor BP and HR frequently during initial dose adjustment and periodically during therapy. Report significant changes.
BPH: Assess patient for symptoms of BPH (urinary hesitancy, feeling of incomplete bladder emptying, interruption of urinary stream, impairment of size and force of urinary stream, terminal urinary dribbling, straining to start flow, dysuria, urgency) before and periodically during therapy.
- Rule out prostatic carcinoma before therapy; symptoms are similar.

Implementation ⬆ ⬇

May be used in combination with diuretics or beta blockers to minimize sodium and water retention in treatment of hypertension. If these are added to terazosin therapy, ↓ dose of terazosin initially and titrate to effect.
Restart use at the initial dose if therapy interrupted for several days or longer.
If used with phosphodiesterase-5 inhibitor therapy, initiate at the lowest dose to avoid hypotension in patients taking terazosin.
PO: Administer daily dose at bedtime. If necessary, dose may be ↑ to twice daily.

Patient/Family Teaching ⬆ ⬇

Explain the purpose and side effects of terazosin to patient. Instruct patient to take medication at the same time each day, preferably at bedtime to minimize side effects, especially the 1st dose. Take missed doses as soon as remembered. If not remembered until next day, omit; do not double doses. Advise patient against sudden discontinuation of drug, as this may cause rebound hypertension. Do not share medication with others, even if they have similar symptoms; may be harmful. Advise patient to read Patient Information before starting and with each Rx refill in case of changes.
- Advise patient to weigh self twice weekly and assess feet and ankles for fluid retention.
- May cause dizziness or drowsiness. Advise patient to avoid driving or other activities requiring alertness until response to the medication is known.
- Caution patient to avoid sudden changes in position to ↓ orthostatic hypotension. Alcohol, CNS depressants (including opioids), standing for long periods, hot showers, and exercising in hot weather should be avoided because of enhanced orthostatic effects.
- Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications, especially NSAIDs or cough/cold/allergy remedies.
- Instruct patient to notify health care professional of medication regimen before any surgery.
Hypertension: Emphasize the importance of continuing to take this medication as directed, even if feeling well. Medication controls but does not cure hypertension.
Encourage patient to comply with additional interventions for hypertension (weight ↓, low-sodium diet, smoking cessation, moderation of alcohol consumption, regular exercise, stress management).
Instruct patient and family on proper technique for BP monitoring. Advise them to check BP at least weekly and to report significant changes.
Rep: Advise women of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. Terazosin is not a preferred antihypertensive for use during pregnancy; consider transitioning to a preferred agent in patients planning to become pregnant.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇