1. Clinical Overview
Ramipril is a long-acting, non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor prodrug. It is hydrolyzed to its active metabolite, ramiprilat, which inhibits ACE, leading to decreased plasma angiotensin II and aldosterone, resulting in vasodilation, reduced blood pressure, and decreased cardiac workload. It is a cornerstone therapy in hypertension, heart failure, and post-myocardial infarction care in India.
| Onset | Duration | Bioavailability |
|---|---|---|
| Peak plasma concentration of ramipril occurs within 1 hour. The antihypertensive effect begins within 1-2 hours, with peak effect at 3-6 hours after oral administration. | The antihypertensive effect is sustained for 24 hours, allowing for once-daily dosing. | Approximately 50-60% for the parent drug. Bioavailability of the active metabolite ramiprilat is about 45%. |
2. Mechanism of Action
Ramipril is a prodrug hydrolyzed to ramiprilat, which competitively inhibits angiotensin-converting enzyme (ACE or kininase II). This inhibition prevents the conversion of angiotensin I to the potent vasoconstrictor angiotensin II and decreases the degradation of bradykinin, a potent vasodilator. The net effects are systemic vasodilation, reduced secretion of aldosterone (leading to decreased sodium and water retention), and increased vasodilatory prostaglandins.
3. Indications & Uses
- Treatment of Hypertension (essential or renovascular)
- Management of Congestive Heart Failure (NYHA Class II-IV) as adjunctive therapy
- Reduction of risk of MI, stroke, and death from cardiovascular causes in patients at high risk (post-MI, PVD, CAD, diabetes with one other CV risk factor)
4. Dosage & Administration
Adult Dosage: Hypertension: Initial: 2.5 mg once daily. Maintenance: 2.5-5 mg once daily. Max: 10 mg/day. Heart Failure/Post-MI: Initial: 1.25-2.5 mg twice daily, titrated upward. High CV Risk: 2.5 mg once daily for 1 week, then 5 mg once daily for 3 weeks, then 10 mg once daily if tolerated.
Administration: Can be taken with or without food. Swallow whole with a glass of water. For once-daily dosing, take at the same time each day, preferably in the morning. If a dose is missed, take it as soon as remembered unless it's almost time for the next dose. Do not double the dose.
5. Side Effects
Common side effects may include:
- Persistent dry, non-productive cough (up to 20%)
- Dizziness, lightheadedness (especially with initial doses)
- Headache
- Fatigue
- Nausea
- Hypotension (symptomatic)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Diuretics (especially loop and thiazide) | Potentiates hypotensive effect; risk of first-dose hypotension. | Major |
| Potassium-sparing diuretics (Spironolactone, Amiloride) | Increased risk of severe hyperkalemia. | Major |
| Potassium supplements/Salt substitutes | Increased risk of hyperkalemia. | Major |
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDs: Ibuprofen, Diclofenac) | May diminish antihypertensive effect and increase risk of renal impairment. | Moderate |
| Lithium | Ramipril may increase lithium levels and toxicity. | Major |
| Aliskiren | Increased risk of hyperkalemia, hypotension, and renal impairment (contraindicated in diabetes/renal impairment). | Major |
| Allopurinol, Procainamide, Immunosuppressants | Increased risk of hypersensitivity reactions, neutropenia. | Moderate |
| Antidiabetics (Insulin, Sulfonylureas) | May enhance hypoglycemic effect. | Moderate |
7. Patient Counselling
- DO take your medicine at the same time every day.
- DO inform all your doctors and dentists you are on Ramipril before any surgery or new prescription.
- DO get regular blood tests (creatinine, potassium) as advised by your doctor.
- DO report any swelling of face, lips, tongue, or throat, or difficulty breathing immediately.
- DONT stop taking the medicine suddenly without consulting your doctor.
- DONT use potassium supplements or salt substitutes without medical advice.
- DONT take over-the-counter NSAIDs (like ibuprofen) for pain without consulting your doctor.
8. Toxicology & Storage
Overdose: Profound hypotension, which may lead to shock, bradycardia, circulatory collapse, electrolyte disturbances (hyperkalemia), and acute renal failure. Symptoms include severe dizziness, lightheadedness, fainting, and extreme weakness.
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.