Olmesartan: Onset and Duration to Full Antihypertensive Effect
Olmesartan begins lowering blood pressure within 1 week, with the majority of its antihypertensive effect evident after 2 weeks of once-daily dosing. 1
Onset of Action
- Initial blood pressure reduction occurs within the first week of starting olmesartan medoxomil therapy. 1
- The antihypertensive effect is largely manifest by 2 weeks, meaning most patients will experience near-maximal blood pressure lowering by this timepoint. 1
- In head-to-head trials, olmesartan demonstrated significant blood pressure reductions as early as week 2 compared to other angiotensin receptor blockers (losartan, valsartan, irbesartan). 2
- When compared to candesartan, most of olmesartan's treatment effect was evident after only 1 or 2 weeks. 2
Time to Maximal Effect
- While onset begins within 1 week, full assessment of blood pressure control should occur after 1-3 months (preferably 1 month) to evaluate both tolerance and complete blood pressure-lowering effect. 3
- The FDA label confirms that olmesartan produces dose-related blood pressure reductions, with 20 mg daily achieving approximately 10/6 mmHg reduction and 40 mg daily achieving approximately 12/7 mmHg reduction over placebo at trough (24 hours post-dose). 1
Sustained Efficacy
- Blood pressure lowering is maintained throughout the entire 24-hour dosing interval with once-daily administration, with trough-to-peak ratios between 60-80%. 1
- No tachyphylaxis (loss of effect) occurs during long-term treatment, and there is no rebound hypertension following abrupt withdrawal after 1 year of therapy. 1
- The antihypertensive effect of olmesartan was maintained in patients treated for up to 1 year in clinical trials. 1
Pharmacokinetic Considerations
- Olmesartan reaches maximum blood concentration approximately 2 hours after oral administration. 4
- The drug has a half-life of approximately 13 hours, which supports once-daily dosing. 4
- Olmesartan is hydrolyzed from its prodrug form (olmesartan medoxomil) in the gut to its active metabolite. 4
Clinical Pitfalls to Avoid
- Do not expect immediate blood pressure control—counsel patients that 1-2 weeks are needed for substantial effect. 1
- Avoid premature dose escalation before 2 weeks, as the drug has not yet reached its full effect. 1
- Black patients may experience smaller blood pressure reductions (as with all ARBs and ACE inhibitors), which is consistent with low-renin hypertension in this population. 1
- If blood pressure remains uncontrolled after 2-4 weeks at maximum dose (40 mg), consider adding hydrochlorothiazide rather than switching agents, as olmesartan demonstrates additional blood pressure lowering when combined with a thiazide diuretic. 1