From the Guidelines
Yes, doxazosin can typically be restarted at 8 mg after a 4-day break, but it's best to restart at a lower dose and titrate up. Recommendation: Restart doxazosin at 1 mg or 2 mg daily, then increase gradually over several days to 1 week until reaching the 8 mg dose. Specific regimen:
- Day 1-2: 1 mg or 2 mg daily
- Day 3-4: 4 mg daily
- Day 5 onwards: 8 mg daily This gradual approach helps minimize side effects like dizziness or orthostatic hypotension that can occur when restarting at a full dose. Doxazosin has a long half-life, so some effects may persist after 4 days, but tolerance to side effects can decrease during the break. Starting low and titrating allows the body to readjust gradually. Take the medication at the same time each day, preferably at bedtime to reduce the risk of dizziness. Monitor blood pressure closely when restarting, especially when standing up. If side effects occur, slow the titration or consult your doctor. According to the guidelines 1, doxazosin is associated with orthostatic hypotension, especially in older adults, and the recommended dose range is 1-16 mg daily. The study by Lepor 1 notes that efficacy is dose-dependent for the titratable alpha blockers doxazosin and terazosin, and maximum tolerable and effective doses have not been defined, but reported clinical data support the efficacy and safety of titrating patients to 8 mg of doxazosin.
From the FDA Drug Label
2.1 Dosing Information Following the initial dose and with each dose increase of doxazosin tablets, monitor blood pressure for at least 6 hours following administration. If doxazosin tablets administration is discontinued for several days, therapy should be restarted using the initial dosing regimen.
- The initial dosing regimen is 1 mg given once daily.
- There is no information that directly supports restarting doxazosin at 8 mg after 4 days.
- Restarting therapy should be done using the initial dosing regimen, which is 1 mg. 2
From the Research
Dosage and Administration of Doxazosin
- The dosage of doxazosin can be titrated up to 8 mg/day if needed, as shown in a study where patients received doxazosin GITS in a single dose of 4 mg/d, which was titrated up to 8 mg/d if the blood pressure was greater than 140/90 mm Hg 3.
- Another study found that doxazosin can be safely administered at a dose of 8 mg/day, with no significant additional effect on blood pressure compared to a dose of 4 mg/day 4.
- The pharmacokinetics of doxazosin are linear between 2 and 8 mg, and the drug can be administered once daily due to its long half-life 5.
Restarting Doxazosin After Discontinuation
- A study found that the antihypertensive effects of doxazosin were abolished within two days after discontinuation of the drug, with no rebound hypertension observed 6.
- However, there is no direct evidence to suggest that doxazosin can be restarted at 8 mg if needed after 4 days, as the studies focused on the initial dosage and titration, rather than restarting the medication after a brief discontinuation.