What is the duration of effect of Olmesartan (angiotensin II receptor antagonist)?

Olmesartan Duration of Effect

Olmesartan provides 24-hour blood pressure control with a single daily dose, with a terminal elimination half-life of approximately 13 hours and achieving >90% inhibition of angiotensin II pressor effects at 24 hours with doses above 40 mg. 1

Pharmacokinetic Profile

The elimination half-life of olmesartan is approximately 13 hours, with biphasic elimination kinetics following the rapid conversion of olmesartan medoxomil to its active form. 1 This relatively long half-life, combined with high receptor affinity, enables true once-daily dosing without loss of efficacy during the 24-hour dosing interval.

• Peak plasma concentrations occur 1-2 hours after oral administration 1
• Steady-state levels are achieved within 3-5 days of once-daily dosing 1
• No plasma accumulation occurs with once-daily administration 1
• Total plasma clearance is 1.3 L/h with renal clearance of 0.6 L/h 1

Pharmacodynamic Duration

Olmesartan doses above 40 mg provide >90% inhibition of angiotensin I-induced pressor effects at 24 hours post-dose, demonstrating dose-dependent duration of pharmacologic effect. 1 This sustained receptor blockade translates directly to clinical blood pressure control throughout the entire dosing interval.

• The duration of inhibitory effect is dose-related, with higher doses providing more complete 24-hour coverage 1
• Doses of 2.5-40 mg inhibit angiotensin I pressor effects in a dose-dependent manner 1
• Blood pressure lowering is maintained throughout the 24-hour period with trough-to-peak ratios of 60-80% 1

Clinical Duration of Antihypertensive Effect

Olmesartan maintains blood pressure control for the full 24-hour dosing interval regardless of administration time (morning or evening). 2, 3 The onset of antihypertensive effect occurs within 1 week, with maximal effect largely manifest after 2 weeks of treatment. 1

• The 24-hour blood pressure reduction is similar whether olmesartan is taken in the morning or evening 2, 3
• The amplitude of the 24-hour blood pressure pattern does not vary with dosing time 3
• No tachyphylaxis develops during long-term treatment up to 1 year 1
• No rebound hypertension occurs following abrupt withdrawal after 1 year of treatment 1

Dosing Implications

A dose of 20 mg daily produces trough sitting blood pressure reductions of approximately 10/6 mmHg over placebo, while 40 mg daily produces reductions of approximately 12/7 mmHg. 1 Doses greater than 40 mg provide little additional antihypertensive effect, though pharmacodynamic studies show enhanced receptor blockade. 1

• The usual starting dose is 20 mg once daily, with titration to 40 mg if needed 4
• Blood pressure lowering effect is maintained with once-daily dosing for up to 2 years 1, 4
• Trough-to-peak ratios of 60-80% confirm adequate 24-hour coverage with once-daily administration 1

Special Populations

In elderly patients (≥65 years), modest accumulation occurs with repeated dosing, with AUC 33% higher corresponding to approximately 30% reduction in renal clearance. 1 However, this does not necessitate dosing more frequently than once daily, as the drug still provides effective 24-hour blood pressure control in this population.