Olmesartan is a medication prescribed for high blood pressure (hypertension). It belongs to a class of drugs called angiotensin receptor blockers (ARBs), which work by influencing specific body pathways.
The Body’s Blood Pressure System
Blood pressure is maintained by a complex network of hormones and enzymes, notably the renin-angiotensin system (RAS). When blood pressure drops, the kidneys release renin. Renin converts angiotensinogen, a liver protein, into angiotensin I.
Angiotensin I is converted into angiotensin II by angiotensin-converting enzyme (ACE), primarily found in the lungs. Angiotensin II is a powerful hormone that narrows blood vessels, directly increasing blood pressure. It also stimulates the adrenal glands to release aldosterone, which promotes sodium and water retention, further elevating blood pressure. Angiotensin II exerts these effects by binding to AT1 receptors, located in various tissues like blood vessels and the adrenal glands.
How Olmesartan Targets Receptors
Olmesartan works by selectively blocking AT1 receptors, preventing angiotensin II from attaching and initiating its blood pressure-raising effects. Olmesartan is a competitive antagonist, directly competing with angiotensin II for AT1 receptor binding sites.
Olmesartan has a significantly higher affinity for AT1 receptors compared to AT2 receptors. This selective binding ensures olmesartan occupies AT1 receptors, preventing angiotensin II from binding and activating them. This blockade disrupts the signaling cascade leading to vasoconstriction and aldosterone release. Olmesartan medoxomil is a prodrug, inactive until metabolized in the gastrointestinal tract into active olmesartan.
Effects on the Body
Blocking AT1 receptors with olmesartan leads to several physiological outcomes that lower blood pressure. One significant effect is vasodilation, the widening of blood vessels. When angiotensin II cannot bind, small artery walls relax, allowing easier blood flow and reducing blood pressure.
Olmesartan also reduces aldosterone secretion from the adrenal glands. With less aldosterone, kidneys reabsorb less sodium and water, decreasing fluid volume and lowering blood pressure. Blocking AT1 receptors also reduces sympathetic nervous system activity, which contributes to elevated blood pressure. This comprehensive action alleviates stress on the heart and blood vessels, mitigating cardiac and vascular remodeling from prolonged high blood pressure.
What Olmesartan Treats
Olmesartan treats essential hypertension (high blood pressure with no identifiable cause). By preventing angiotensin II’s constrictive and fluid-retaining actions, olmesartan effectively lowers blood pressure. Its mechanism also protects organs often affected by high blood pressure, including reducing heart strain and safeguarding kidney function. This makes it suitable for managing hypertension and associated organ health.