Can Doxazosin (alpha-1 adrenergic blocker) be administered at bedtime?

Doxazosin Administration at Bedtime

Yes, doxazosin can be given at bedtime, and bedtime dosing may actually be superior to morning dosing for achieving 24-hour blood pressure control. 1

Evidence for Bedtime Dosing

Pharmacokinetic Support

• The FDA label explicitly states that doxazosin can be administered "either in the morning or evening" for both benign prostatic hyperplasia (BPH) and hypertension, confirming bedtime dosing is an approved option. 2
• Pharmacokinetic studies demonstrate similar safety profiles for morning versus evening dosing, with no clinically significant differences in drug exposure. 2

Superior Blood Pressure Control with Bedtime Dosing

• A randomized trial of 91 hypertensive patients showed that bedtime administration of doxazosin GITS significantly reduced 24-hour blood pressure (6.9/5.9 mmHg systolic/diastolic in monotherapy), while morning dosing produced minimal, non-significant reductions (1.8/3.2 mmHg). 1
• Morning dosing failed to provide adequate nocturnal blood pressure control, whereas bedtime dosing achieved consistent BP reduction throughout both day and nighttime hours. 1
• Bedtime doxazosin effectively suppresses morning hypertension, which is particularly important given the increased cardiovascular risk associated with morning BP surges. 3

Practical Administration Guidelines

Dosing Schedule

• For BPH: Start with 1 mg once daily at bedtime, titrate at 1-2 week intervals up to maximum 8 mg daily as needed. 2
• For hypertension: Start with 1 mg once daily at bedtime, may double dose up to 16 mg daily to achieve BP goals. 2

Critical Safety Monitoring

• Monitor blood pressure for at least 6 hours following the initial dose and with each dose increase to detect orthostatic hypotension. 2
• Alpha-1 blockers like doxazosin are associated with orthostatic hypotension, especially in older adults, making the first-dose effect a key concern. 4
• If therapy is discontinued for several days, restart using the initial 1 mg dosing regimen. 2

Important Caveats

Not First-Line for Hypertension

• Doxazosin should be considered a second-line agent for hypertension, particularly useful in patients with concomitant BPH. 4
• The ALLHAT trial demonstrated that doxazosin was associated with significantly increased risk of congestive heart failure compared to thiazide diuretics. 4
• Doxazosin is also associated with weight gain, likely due to extracellular fluid volume expansion. 4

Contrast with General Bedtime Dosing Recommendations

• While bedtime dosing of doxazosin specifically shows benefit, current guidelines do not recommend preferential bedtime dosing of antihypertensives as a general principle, as earlier benefits have not been reproduced in recent large trials. 4
• This creates an important distinction: doxazosin may be an exception where bedtime dosing offers specific advantages based on its pharmacodynamic profile. 1

Monitoring Requirements

• Routinely monitor blood pressure in all patients receiving doxazosin, regardless of indication. 2
• The maximum hypotensive effects occur 2-6 hours after dosing, which with bedtime administration would occur during sleep when orthostatic stress is minimal. 2