1. Clinical Overview
A fixed-dose combination (FDC) antihypertensive medication containing an angiotensin II receptor blocker (ARB), Olmesartan Medoxomil, and a dihydropyridine calcium channel blocker (CCB), Amlodipine. This combination provides synergistic blood pressure lowering through complementary mechanisms, offering improved efficacy and tolerability compared to monotherapy. It is a first-line treatment for essential hypertension in patients requiring more than one drug to achieve target BP.
| Onset | Duration | Bioavailability |
|---|---|---|
| Olmesartan: 1-2 hours; Amlodipine: 6-12 hours. | Olmesartan: >24 hours; Amlodipine: 24-48 hours. | Olmesartan Medoxomil: ~26%; Amlodipine: 64-90%. |
2. Mechanism of Action
Combined blockade of the Renin-Angiotensin-Aldosterone System (RAAS) and inhibition of vascular smooth muscle calcium influx. Olmesartan selectively blocks the binding of angiotensin II to the AT1 receptor, preventing vasoconstriction, aldosterone secretion, and sympathetic activation. Amlodipine inhibits transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle, causing peripheral arterial vasodilation and reduced peripheral vascular resistance.
3. Indications & Uses
- Essential Hypertension (when monotherapy is inadequate)
4. Dosage & Administration
Adult Dosage: One tablet (Olmesartan 40mg + Amlodipine 5mg) orally once daily. Dose may be titrated after 2-4 weeks. Maximum: Olmesartan 40mg + Amlodipine 10mg daily.
Administration: Can be taken with or without food. Swallow whole with a glass of water. Administer at the same time each day, preferably in the morning. Do not crush or chew. Dose is not influenced by food.
5. Side Effects
Common side effects may include:
- Dizziness
- Headache
- Peripheral edema (less frequent than with Amlodipine monotherapy)
- Flushing
- Palpitations
- Fatigue
- Nausea
- Abdominal pain
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Antihypertensives (Diuretics, Beta-blockers) | Additive hypotensive effect; risk of severe hypotension. | Major |
| Potassium supplements / Potassium-sparing diuretics (Spironolactone, Eplerenone) | Increased risk of hyperkalemia. | Major |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | May reduce antihypertensive effect and increase risk of renal impairment, especially in elderly/volume-depleted. | Major |
| Lithium | Olmesartan may increase lithium levels and toxicity. Monitor serum lithium. | Major |
| Strong CYP3A4 Inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin, Ritonavir) | Increase Amlodipine plasma concentration, risk of hypotension and edema. | Moderate |
| Simvastatin | Amlodipine may increase simvastatin exposure, increasing risk of myopathy. Limit simvastatin dose to 20mg daily. | Moderate |
| Sildenafil, Tadalafil (for PAH) | Additive hypotensive effect. | Moderate |
| Aliskiren | Increased risk of hypotension, hyperkalemia, and renal impairment. Contraindicated in diabetes/renal impairment. | Major |
7. Patient Counselling
- DO take the medicine at the same time every day.
- DO continue taking even if you feel well. Hypertension often has no symptoms.
- DO get your blood pressure checked regularly.
- DO inform all your doctors and dentists you are on this medication.
- DONT stop taking suddenly; can cause rebound hypertension.
- DONT take a double dose if you miss one. Take the next dose at the regular time.
- DONT use potassium supplements or salt substitutes without doctor's advice.
- DONT take over-the-counter NSAIDs (like ibuprofen) for pain without consulting your doctor.
8. Toxicology & Storage
Overdose: Profound hypotension, reflex tachycardia, bradycardia (with Amlodipine), circulatory shock, electrolyte disturbances (hyperkalemia with Olmesartan).
Storage: Store below 30°C. Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach of children. Do not use after the expiry date printed on the pack.