1. Clinical Overview
A fixed-dose combination (FDC) of an angiotensin II receptor blocker (ARB) and a unique dual L/N-type calcium channel blocker (CCB) used for the management of essential hypertension. This combination provides synergistic blood pressure lowering by blocking the renin-angiotensin-aldosterone system (RAAS) and inhibiting calcium influx through both L-type and N-type channels, offering potential benefits in reducing reflex tachycardia and providing renal protection.
| Onset | Duration | Bioavailability |
|---|---|---|
| Olmesartan: 1-2 hours; Cilnidipine: 1-2 hours. Significant blood pressure reduction typically observed within 2 weeks of starting therapy. | Olmesartan: >24 hours; Cilnidipine: Approximately 24 hours. The combination provides sustained 24-hour blood pressure control with once-daily dosing. | Olmesartan Medoxomil: ~26%; Cilnidipine: ~13% (due to significant first-pass metabolism). |
2. Mechanism of Action
The combination exerts a complementary and synergistic antihypertensive effect. Olmesartan selectively and competitively blocks the binding of angiotensin II to the AT1 receptor, inhibiting its vasoconstrictor and aldosterone-secreting effects. Cilnidipine inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle via voltage-dependent L-type calcium channels, causing vasodilation. Uniquely, cilnidipine also blocks N-type calcium channels, which are present on sympathetic nerve terminals, inhibiting norepinephrine release and attenuating reflex sympathetic activation.
3. Indications & Uses
- Essential Hypertension (when monotherapy is insufficient)
4. Dosage & Administration
Adult Dosage: One tablet (Olmesartan 20mg + Cilnidipine 10mg) once daily. Dose may be titrated to Olmesartan 40mg + Cilnidipine 10mg after 2-4 weeks if needed. Maximum: Olmesartan 40mg + Cilnidipine 20mg per day.
Administration: Can be taken with or without food. However, for consistent effect, administer at the same time each day, preferably in the morning. Swallow whole with a glass of water; do not crush or chew. Food, especially high-fat meals, increases cilnidipine absorption significantly.
5. Side Effects
Common side effects may include:
- Dizziness
- Headache
- Peripheral edema (less frequent than with amlodipine)
- Fatigue
- Flushing
- Palpitations (less frequent)
- Nausea
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Antihypertensives (Diuretics, Beta-blockers, ACE inhibitors) | Additive hypotensive effect, risk of severe hypotension. | Major |
| Potassium supplements / Potassium-sparing diuretics (Spironolactone, Amiloride) | Increased risk of hyperkalemia, especially in renal impairment. | Major |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | May reduce antihypertensive effect; risk of renal impairment and hyperkalemia. | Moderate |
| Lithium | Increased serum lithium levels and toxicity risk. | Major |
| Strong CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Clarithromycin, Ritonavir) | Increased cilnidipine plasma concentration, risk of adverse effects (edema, hypotension). | Moderate |
| Strong CYP3A4 Inducers (Rifampicin, Phenytoin, Carbamazepine) | Decreased cilnidipine plasma concentration, reduced efficacy. | Moderate |
| Aliskiren | Increased risk of renal impairment, hypotension, and hyperkalemia; contraindicated in diabetes/renal impairment. | Major |
| Digoxin | Cilnidipine may increase digoxin levels; monitor for toxicity. | Moderate |
| Grapefruit Juice | Inhibits CYP3A4, may increase cilnidipine levels. | Moderate |
7. Patient Counselling
- DO take the medication at the same time every day, preferably in the morning.
- DO continue taking even if you feel well; hypertension often has no symptoms.
- DO inform all your doctors and dentists you are on this medication.
- DO get regular blood pressure, kidney function (creatinine), and potassium checks.
- DONT stop taking abruptly without consulting your doctor.
- DONT take over-the-counter NSAIDs (like ibuprofen) for pain/fever without asking your doctor.
- DONT use potassium supplements or salt substitutes containing potassium without medical advice.
- DONT double the dose if you miss one; take it as soon as you remember, but skip if it's almost time for the next dose.
8. Toxicology & Storage
Overdose: Profound hypotension, tachycardia (or bradycardia due to vagal reflex), dizziness, syncope, shock, electrolyte disturbances (hyperkalemia), acute renal failure.
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.