What is the recommended dosing for Terazosin (alpha-1 blocker) in the treatment of benign prostatic hyperplasia (BPH) or hypertension?

Terazosin Dosing for BPH and Hypertension

For benign prostatic hyperplasia (BPH), terazosin should be initiated at 1 mg at bedtime, with gradual titration to an effective dose of 10 mg once daily for 4-6 weeks to achieve optimal clinical response. 1

Dosing Protocol for BPH

Initial Dosing

• Start with 1 mg at bedtime for all patients
• This initial dose should not be exceeded to minimize risk of severe hypotensive response 1
• Close monitoring during initial administration is essential

Dose Titration

• Increase dose in a stepwise fashion:
  • 1 mg → 2 mg → 5 mg → 10 mg once daily
• Titrate to achieve desired improvement in symptoms and/or flow rates
• 10 mg once daily is generally required for clinical response
• Minimum treatment duration of 4-6 weeks at 10 mg to assess beneficial response 1

Maximum Dosing

• Some patients may respond to 20 mg daily, but insufficient data exists to make definitive conclusions about this dose
• Insufficient data to support higher doses for non-responders to 20 mg daily 1

Dosing Protocol for Hypertension

Initial Dosing

• Start with 1 mg at bedtime for all patients
• This initial dosing regimen must be strictly observed to minimize risk of severe hypotensive effects 1

Dose Titration

• Dose may be slowly increased to achieve desired blood pressure response
• Usual recommended dose range: 1-5 mg once daily
• Some patients may benefit from doses up to 20 mg per day
• Doses over 20 mg do not appear to provide further blood pressure effect 1

Monitoring

• Blood pressure should be monitored at the end of dosing interval
• Consider measuring blood pressure 2-3 hours after dosing to evaluate maximum and minimum responses
• If response diminishes at 24 hours, consider increased dose or twice daily regimen 1

Restarting Therapy

• If terazosin administration is discontinued for several days or longer, therapy should be reinstituted using the initial dosing regimen of 1 mg at bedtime 1

Efficacy

• Alpha blockers like terazosin produce on average a 4-6 point improvement in AUA Symptom Index 2
• Terazosin increases peak urinary flow rate by approximately 2 ml/s compared to baseline 3
• Reduces residual urine volume significantly 3

Side Effects and Precautions

Common Side Effects

• Orthostatic hypotension
• Dizziness
• Tiredness (asthenia)
• Ejaculatory problems
• Nasal congestion 2

Special Precautions

• Use caution when administering concomitantly with other antihypertensive agents, especially calcium channel blocker verapamil
• Hypotension has been reported when used with PDE-5 inhibitors 1
• In hypertensive patients with cardiac risk factors, alpha blocker monotherapy may not constitute optimal management of concomitant hypertension 2

Blood Pressure Effects

• In normotensive and controlled hypertensive patients, terazosin produces no clinically significant mean changes in systolic or diastolic blood pressure
• In hypertensive patients, terazosin produces clinically significant reductions in blood pressure 4

Clinical Pearls

• First-dose effect: Unusually large falls in blood pressure can occur after first dose or first few doses
• Terazosin is safe for both normotensive and hypertensive men with BPH, including those taking additional antihypertensive medications 4
• Terazosin has minimal effect on prostate volume but significantly improves symptoms and flow rates 5
• Patients should be advised to rise slowly from sitting or lying positions and to take medication at bedtime to minimize orthostatic effects

By following this dosing protocol and monitoring guidelines, terazosin can be safely and effectively used for the treatment of BPH and hypertension.