Generic Name

Terazosin Hydrochloride

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Classification

FDA Approved Indications

• Benign prostatic hyperplasia (BPH)
• Hypertension

Mechanism of Action

Terazosin selectively antagonizes alpha-1 adrenergic receptors in vascular smooth muscle and the prostate, leading to vasodilation and relaxation of prostate smooth muscle, which reduces urinary resistance and blood pressure.

Dosage and Administration

Adult: Initial dose for hypertension: 1 mg at bedtime, titrated by 1 mg every 3-7 days to a typical dose of 2-10 mg once daily. For BPH: 1 mg at bedtime, titrated as needed.

Pediatric: Not commonly used in pediatric patients.

Geriatric: Start at lower dose; monitor closely due to increased sensitivity to hypotension.

Renal Impairment: Use with caution; no specific dose adjustment, but monitor blood pressure.

Hepatic Impairment: Use with caution; no specific dose adjustment.

Pharmacokinetics

Absorption: Well absorbed after oral administration, food may delay absorption.

Distribution: Extensively bound to plasma proteins (~78%).

Metabolism: Primarily hepatic via hepatic oxidation and conjugation.

Excretion: Excreted in urine and feces.

Half Life: approximately 12 hours.

Contraindications

• Hypersensitivity to terazosin or other quinazolines.

Precautions

• Orthostatic hypotension, particularly at initiation or dose escalation.
• History of syncope.
• Use with caution in patients with cardiovascular disease, hepatic impairment, or renal impairment.

Adverse Reactions - Common

• Dizziness (Common)
• Headache (Common)
• Fatigue (Common)
• Palpitations (Less common)

Adverse Reactions - Serious

• Syncope (fainting due to hypotension) (Less common)
• Priapism (Rare)
• Severe hypotension/shock (Rare)

Drug-Drug Interactions

• Other antihypertensives, especially other vasodilators
• Phosphodiesterase inhibitors (e.g., sildenafil) which can enhance hypotensive effects

Drug-Food Interactions

• Alcohol may enhance hypotensive effects.

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Rise slowly from sitting or lying position to prevent dizziness.
• Avoid alcohol and abrupt cessation.
• Report dizziness, fainting, or priapism immediately.

Special Considerations

Black Box Warnings:

• Potential for profound hypotension and syncope, especially after the first dose or dose increase.
• Use with caution in patients with a history of orthostatic hypotension.

Genetic Factors: None specified.

Lab Test Interference: May affect blood pressure readings.

Overdose Management

Signs/Symptoms: Severe hypotension, dizziness, syncope.

Treatment: Cease medication immediately, apply pressure to bleeding sites if any, administer fluids or vasopressors as needed, and provide symptomatic support.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable under recommended storage conditions.