1. Clinical Overview
A fixed-dose combination (FDC) antihypertensive agent containing an angiotensin II receptor blocker (ARB) and a beta-1 selective adrenergic blocker. Olmesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II, while Metoprolol Succinate reduces cardiac output, renin release, and sympathetic nervous system activity. This combination provides synergistic blood pressure control through complementary mechanisms, often allowing for lower doses of each component and improved tolerability. It is a mainstay in the management of essential hypertension in the Indian population, particularly in patients with concomitant conditions like tachycardia or ischemic heart disease.
| Onset | Duration | Bioavailability |
|---|---|---|
| Olmesartan: 1-2 hours; Metoprolol: ~1 hour (for heart rate reduction). Significant antihypertensive effect is typically observed within 2-4 weeks of continuous therapy. | Olmesartan: >24 hours; Metoprolol Succinate (Extended-Release): 24 hours. The combination provides sustained 24-hour blood pressure control with once-daily dosing. | Olmesartan Medoxomil: ~26%; Metoprolol Succinate: ~40-50%. |
2. Mechanism of Action
The combination exerts a dual antihypertensive action. Olmesartan selectively and competitively blocks the binding of angiotensin II to the AT1 receptor subtype found in vascular smooth muscle and the adrenal gland, preventing vasoconstriction and aldosterone release. Metoprolol Succinate is a cardioselective (beta-1) adrenergic receptor antagonist that reduces heart rate, myocardial contractility, and cardiac output. It also inhibits renin release from the kidneys and modulates central sympathetic outflow. Together, they reduce peripheral vascular resistance and cardiac workload.
3. Indications & Uses
- Essential Hypertension (Stage 1 & 2)
4. Dosage & Administration
Adult Dosage: One tablet (Olmesartan 20mg + Metoprolol Succinate 25mg) once daily, preferably in the morning. Dose may be titrated after 2-4 weeks to a maximum of Olmesartan 40mg + Metoprolol Succinate 100mg once daily, using separate component titrations or higher strength FDCs.
Administration: Swallow the tablet whole with a glass of water, with or without food. Do not crush, chew, or split the tablet as it contains extended-release metoprolol. Take at the same time each day. If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose.
5. Side Effects
Common side effects may include:
- Dizziness
- Fatigue
- Headache
- Bradycardia
- Cold extremities
- Nausea
- Diarrhea (esp. with Olmesartan - can be sprue-like enteropathy in rare cases)
- Upper respiratory tract infection symptoms
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Antihypertensives (Diuretics, CCBs, other ARBs/ACEIs) | Additive hypotensive effect, risk of severe hypotension. | Major |
| Digoxin | Metoprolol may increase digoxin concentration; risk of bradycardia. | Moderate |
| Antiarrhythmics (Amiodarone, Disopyramide) | Increased risk of bradycardia and myocardial depression. | Major |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | May reduce antihypertensive effect of Olmesartan; increase risk of renal impairment and hyperkalemia. | Moderate |
| Lithium | Beta-blockers may increase lithium toxicity; monitor levels. | Moderate |
| Clonidine | Risk of severe rebound hypertension if clonidine is withdrawn while on beta-blocker. | Major |
| CYP2D6 Inhibitors (Fluoxetine, Paroxetine, Quinidine) | Increase Metoprolol plasma levels, enhancing its effects and side effects. | Moderate |
| Insulin/Oral Hypoglycemics | Metoprolol may mask tachycardia as a sign of hypoglycemia; may potentiate hypoglycemia. | Moderate |
| Calcium Channel Blockers (Verapamil, Diltiazem) | Potentiate bradycardia and AV block; additive negative inotropic effect. | Major |
| Potassium supplements/Potassium-sparing diuretics (Spironolactone) | Increased risk of hyperkalemia with Olmesartan. | Moderate |
7. Patient Counselling
- Do take the tablet at the same time every day.
- Do not stop taking this medicine suddenly, especially Metoprolol, as it can cause severe rebound hypertension, angina, or heart attack. Taper under doctor's guidance.
- Do inform all your doctors and dentists that you are on this medication before any surgery.
- Do monitor your blood pressure and pulse rate regularly as advised.
- Do not take over-the-counter NSAIDs (like ibuprofen) for pain without consulting your doctor.
- Do not take potassium supplements or salt substitutes containing potassium without medical advice.
8. Toxicology & Storage
Overdose: Olmesartan: Profound hypotension, tachycardia, bradycardia, dizziness, circulatory collapse. Metoprolol: Severe bradycardia, hypotension, heart failure, bronchospasm, hypoglycemia, coma, seizures, and cardiorespiratory arrest.
Storage: Store below 30°C, in a cool, dry place, protected from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.