Is Olmesartan a Beta Blocker?
No, olmesartan is not a beta blocker—it is an angiotensin II receptor blocker (ARB), a completely different class of antihypertensive medication. 1
Drug Classification
Olmesartan medoxomil is specifically an angiotensin II type 1 (AT₁) receptor antagonist that works by selectively blocking the binding of angiotensin II to the AT₁ receptor in vascular smooth muscle, thereby preventing vasoconstriction and aldosterone release. 1, 2
- Mechanism of action: Olmesartan blocks the vasoconstrictor effects of angiotensin II by antagonizing the AT₁ receptor, with more than 12,500-fold greater affinity for the AT₁ receptor than for the AT₂ receptor. 1
- Key distinction: Unlike ACE inhibitors, olmesartan does not inhibit ACE (kininase II) and therefore does not affect bradykinin degradation. 1
- Pharmacologic profile: It acts as a competitive and insurmountable angiotensin II antagonist with high receptor affinity and no cytochrome P450 interaction. 3
Comparison with Beta Blockers
Guidelines clearly distinguish olmesartan from beta blockers by listing them in separate drug categories:
- ACC/AHA guidelines list olmesartan among angiotensin receptor blockers, while beta blockers (bisoprolol, carvedilol, metoprolol succinate) are categorized separately for heart failure management. 4
- ESC guidelines specifically warn against combining olmesartan with beta blockers and ACE inhibitors in certain contexts (e.g., HFpEF), demonstrating these are distinct drug classes. 4
Clinical Use
Olmesartan is indicated for hypertension treatment with once-daily dosing of 20-40 mg, either as monotherapy or in combination with other antihypertensives including thiazide diuretics or calcium channel blockers. 5, 1
- Dosing: The absolute bioavailability is approximately 26%, with peak plasma concentration reached after 1-2 hours and a terminal elimination half-life of approximately 13 hours. 1
- Combination therapy: Can be combined with diuretics or calcium channel blockers, but should never be combined with other renin-angiotensin system blockers (ACE inhibitors, other ARBs, or aliskiren). 5, 6