What is the recommended dosage and treatment protocol for Terazosin (alpha-blocker) in patients with benign prostatic hyperplasia (BPH) and hypertension?

Terazosin Dosing and Treatment Protocol for BPH and Hypertension

For BPH, start terazosin at 1 mg at bedtime and titrate stepwise to 10 mg once daily over 4-6 weeks, which is the dose generally required for clinical response; however, do not rely on terazosin alone for optimal hypertension management in patients with cardiac risk factors. 1

Initial Dosing Protocol

• Always start at 1 mg at bedtime for all patients, regardless of indication (BPH or hypertension), and this dose must not be exceeded as an initial dose to minimize severe hypotensive response risk 1
• Patients require close monitoring during initial administration to detect orthostatic hypotension, dizziness, and syncope 1, 2
• If therapy is discontinued for several days or longer, restart using the initial 1 mg dosing regimen 1

Dose Titration for BPH

• Increase in a stepwise fashion: 1 mg → 2 mg → 5 mg → 10 mg once daily at bedtime 1
• Target dose is 10 mg once daily, as this is generally required for clinical response in BPH 1, 3
• Allow a minimum of 4-6 weeks at 10 mg to assess therapeutic benefit before considering the patient a non-responder 1
• Efficacy is dose-dependent—higher doses produce greater symptom improvement 3, 4
• Some patients may respond to 20 mg daily, though insufficient data exist to support routine use of doses above 20 mg 1

Expected Clinical Outcomes

• Terazosin produces an average 4-6 point improvement in AUA Symptom Index, which patients perceive as meaningful change 3, 4
• Peak urinary flow rates increase by approximately 50% and mean flow rates by 46% 5
• Network meta-analyses show -3.7 point improvement in IPSS compared to placebo 4
• Symptom improvement includes 67% reduction in obstructive symptoms and 35% reduction in irritative symptoms 5

Adverse Effects and Monitoring

Common side effects (in order of frequency):

• Orthostatic hypotension 3, 4, 2
• Dizziness (most common cause of discontinuation at 2.0%) 3, 2
• Asthenia/tiredness 3, 4
• Ejaculatory dysfunction 3, 4
• Nasal congestion 3, 4
• Headache (1.1% discontinuation rate) 2

Critical safety considerations:

• Only 0.6% of patients experience syncope, typically at initiation or dose escalation 2
• Side effects are generally mild to moderate and resolve after discontinuation 2
• Overall discontinuation rate due to adverse events is 9%, not significantly different from placebo (7%) 2
• Warn patients with planned cataract surgery about intraoperative floppy iris syndrome (IFIS) risk 4

Blood Pressure Effects by Patient Type

Normotensive patients: Terazosin produces minimal, clinically insignificant changes in blood pressure 2, 6

Controlled hypertensive patients (on other antihypertensives): No clinically significant blood pressure changes occur 6

Untreated hypertensive patients: Substantial decreases in both systolic and diastolic blood pressure occur 2, 6

Critical Hypertension Management Caveat

In men with hypertension and cardiac risk factors, alpha blocker monotherapy (including terazosin) should NOT be assumed to constitute optimal hypertension management 3. This is based on data showing doxazosin monotherapy was associated with higher incidence of congestive heart failure compared to other antihypertensives 3. These patients require separate, optimized antihypertensive therapy 3, 7.

Drug Interactions and Combination Therapy

• Exercise caution when combining with other antihypertensives, especially calcium channel blockers like verapamil, due to significant hypotension risk 1
• Hypotension reported when combined with PDE-5 inhibitors 1
• When combining with other antihypertensives, dosage reduction and retitration of either agent may be necessary 1
• Terazosin can be safely administered with concomitant antihypertensive medications without adverse effects 6

Comparative Considerations

While terazosin is equally effective as other alpha blockers (alfuzosin, doxazosin, tamsulosin) for BPH symptom relief 3, 4, 7, tamsulosin and alfuzosin are preferred first-line agents due to superior tolerability with fewer cardiovascular side effects 7. Specifically:

• Tamsulosin has lower orthostatic hypotension risk but higher ejaculatory dysfunction rates 3, 4
• Terazosin requires dose titration, whereas tamsulosin does not 7
• Terazosin and doxazosin have higher rates of dizziness, fatigue, and orthostatic hypotension 7

Practical Algorithm

For BPH patients without hypertension or with controlled hypertension:

• Start terazosin 1 mg at bedtime
• Increase to 2 mg after 1 week if tolerated
• Increase to 5 mg after another week if tolerated
• Increase to 10 mg (target dose) and maintain for 4-6 weeks minimum
• Consider 20 mg if inadequate response at 10 mg after 4-6 weeks

For BPH patients with untreated hypertension:

• Use same titration protocol as above
• Expect substantial blood pressure reduction
• Do NOT rely on terazosin alone for hypertension management if cardiac risk factors present
• Add separate, optimized antihypertensive therapy

For patients who discontinue therapy:

• Always restart at 1 mg regardless of previous dose
• Retitrate using standard protocol