What is the recommended rate of increase for prazosin (alpha-blocker) dosage in patients with hypertension, benign prostatic hyperplasia, or post-traumatic stress disorder (PTSD) to minimize the risk of hypotension?

Prazosin Dose Titration

Start prazosin at 1 mg at bedtime and increase by 1-2 mg every few days until an effective dose is reached, monitoring for orthostatic hypotension after each increase. 1

Initial Dosing Strategy

• Begin with 1 mg at bedtime to minimize first-dose hypotension, which occurs in approximately 0.15% of patients (1 in 667) when this conservative starting dose is used 2, 3
• Taking the first dose at bedtime is critical to avoid syncope and orthostatic symptoms 3
• Monitor blood pressure after the first dose, particularly in elderly patients or those on concurrent antihypertensives 2

Titration Schedule

For PTSD-Associated Nightmares

• Increase by 1-2 mg every few days based on clinical response and tolerability 1
• Target maintenance dose: 2-6 mg nightly for most civilian patients with PTSD 4
• Higher doses (9.5-13.3 mg nightly) were used successfully in military veterans with combat-related PTSD in Level 1 studies 1
• Some treatment-resistant cases may require doses up to 30-45 mg daily (divided dosing), though this is off-label and requires careful monitoring 5
• Clinical response typically occurs within 3-9 weeks of reaching therapeutic dose 1

For Hypertension

• Initial: 1 mg two or three times daily 2
• Maintenance: 6-15 mg daily in divided doses (most common therapeutic range) 2
• May slowly increase to maximum 20 mg daily in divided doses; doses above 20 mg rarely provide additional benefit, though some patients respond to up to 40 mg daily 2
• After initial titration, some patients can be maintained on twice-daily dosing 2

For Benign Prostatic Hyperplasia

• Dose range: 1-9 mg daily with 60-70% of patients experiencing symptom relief 6
• Use the same gradual titration approach as for hypertension 6

Critical Monitoring Points

• Check orthostatic blood pressure after each dose increase, particularly the first dose 1, 2
• Monitor for dizziness, lightheadedness, and syncope—the primary dose-limiting adverse effects 1, 3
• If adding other antihypertensives or diuretics, reduce prazosin to 1-2 mg three times daily and retitrate 2
• If adding PDE-5 inhibitors, start the PDE-5 inhibitor at the lowest dose due to additive hypotensive effects 2

Common Pitfalls to Avoid

• Never start at doses higher than 1 mg unless the patient is already on prazosin—this dramatically increases first-dose hypotension risk 3
• Do not increase too rapidly—the "every few days" interval allows assessment of blood pressure effects before further escalation 1
• Withhold diuretics for 1 day before initiating prazosin to reduce orthostatic hypotension risk 3
• Be aware that fluid retention may develop with long-term therapy, potentially requiring diuretic addition 3

Special Populations

• Elderly patients: Use extra caution with titration and monitor closely for falls related to orthostatic hypotension 2
• Patients with renal impairment: Prazosin is particularly useful in this population, but maintain the same cautious titration schedule 3
• Patients on hemodialysis: Can safely use prazosin with standard titration 3