Dosing and uses of Hytrin (terazosin)
Adult dosage forms and strengths
capsule
- 1mg
- 2mg
- 5mg
- 10mg
Benign Prostate Hyperplasia
Initial: 1 mg PO qHs
May gradually increase to 5 mg PO qHS; up to 20 mg/day beneficial for some
Dosing considerations
- Give first dose and subsequent increases at bedtime to avoid syncope
- May take with food
Hypertension
Initial: 1 mg PO qHs
Maintenance: 1-5 mg/day or q12hr; may increase to ≤20 mg/day
Dosing considerations
- Give first dose and subsequent increases at bedtime to avoid syncope
- May take with food
Dosing Modifications
Hepatic impairment: Use with caution
Pediatric dosage forms and strengths
capsule
- 1mg
- 2mg
- 5mg
- 10mg
Hypertension (Off-label)
1 mg/day PO; increase dose gradually as necessary; up to maximum of 20 mg/day
Geriatric dosage forms and strengths
Hypertension
Initial: 0.5 mg PO qHS and titrate to response
Dosing considerations
Avoid use for hypertension; high risk of orthostatic hypotension (Beers criteria)
May cause significant orthostatic hypotension and syncope
Lower initial doses than those used for nongeriatric adults, as well as gradual adjustments, are recommended for hypertension
Give first dose and subsequent increases at bedtime to avoid syncope
Adverse effects such as dry mouth and urinary complications can be bothersome in the elderly
May take with food
Hytrin (terazosin) adverse (side) effects
>10%
Dizziness (10-20%)
Asthenia (2-13%)
1-10%
Hypotension (3-7%)
Rhinitis/nasal congestion (2-6%)
Lightheadedness (3-5%)
Somnolence (3-5%)
Palpitation (4%)
Nausea (2-4%)
Edema (3%)
Sinusitis (3%)
Dyspnea (2-3%)
Fatigue (2.5%)
Headache (2.5%)
Back pain (2.4%)
Flulike syndrome (2.4%)
Tachycardia (2%)
Amblyopia (1-2%)
Blurred vision (1-2%)
Impotence (1-2%)
Syncope (1%)
Warnings
Contraindications
Hypersensitivity to terazosin, other quinazolines
Cautions
Prostate carcinoma
Liver disease
May cause first-dose syncope/sudden LOC and orthostatic hypotension; minimize effect by using small first dose at bedtime; increase dose slowly
Concomitant use of other antihypertensives (additive hypotensive effects)
May exacerbate heart failure
Concomitant administration with PDE-5 inhibitor (eg, sildenafil) can result in additive blood pressure-lowering effects and symptomatic hypotension; initiate PDE-5 inhibitor therapy at lowest dose
Risk of priapism (rare but needs medical attention)
Pregnancy and lactation
Pregnancy category: C
Lactation: Not known if excreted into breast milk; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Hytrin (terazosin)
Mechanism of action
Blocks postsynaptic alpha-1 receptor; alpha blockade causes arterial and venous dilation
Selective agents cause less tachycardia than do nonselective agents
Absorption
Bioavailability: 90%
Onset (hypertension): 3 hr
Onset (benign prostate hyperplasia): 2 weeks
Duration: 24 hr
Peak response (benign prostate hyperplasia): 4-6 weeks
Peak plasma time: 1 hr
Distribution
Protein bound: 90-94%
Vd: 25-30 L
Metabolism
Metabolized extensively via hydrolysis, O-demethylation, and N-dealkylation in liver
Metabolites: 6- and 7-O-demethyl terazosin, piperazine derivative, diamine metabolite
Elimination
Half-life: 9-12 hr
Renal clearance: 9-12.5 mL/min
Excretion: Feces (55-60%); urine (40%)
