1. Clinical Overview
Ramipril is a long-acting, non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor prodrug. It is hydrolyzed in the liver to its active metabolite, ramiprilat. It is a cornerstone therapy in the management of hypertension, heart failure, and post-myocardial infarction, and for renal protection in diabetic nephropathy. It reduces the formation of angiotensin II, a potent vasoconstrictor, leading to vasodilation, reduced aldosterone secretion, and decreased sodium and water retention.
| Onset | Duration | Bioavailability |
|---|---|---|
| 1-2 hours for peak plasma concentration of ramipril; 2-4 hours for peak effect of ramiprilat. | Approximately 24 hours, allowing for once-daily dosing. | Approximately 50-60% for the parent drug. |
2. Mechanism of Action
Ramipril is a prodrug hydrolyzed to ramiprilat, which competitively inhibits angiotensin-converting enzyme (ACE, 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 reduction in angiotensin II leads to decreased vasoconstriction, reduced secretion of aldosterone (lowering sodium and water reabsorption), and possibly reduced sympathetic nervous system activity. Increased bradykinin levels contribute to vasodilation but also to side effects like cough.
3. Indications & Uses
- Hypertension (essential and renovascular)
- Congestive Heart Failure (post-MI and symptomatic CHF)
- Post-Myocardial Infarction (to reduce risk of death, reinfarction, stroke)
4. Dosage & Administration
Adult Dosage: Hypertension: Initial 2.5mg once daily, adjust based on response. Maintenance: 2.5mg to 10mg once daily. Max: 10mg/day. Heart Failure/Post-MI: Initial 1.25mg to 2.5mg twice daily, titrated upward. Max: 10mg/day (in divided doses). Cardiovascular Risk Reduction: Initial 2.5mg once daily, may increase to 10mg/day.
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. Do not crush or chew. In heart failure, twice-daily dosing may be used.
5. Side Effects
Common side effects may include:
- Persistent dry, non-productive cough (up to 20% of patients)
- Dizziness, lightheadedness (especially with first doses)
- Headache
- Fatigue
- Nausea
- Hypotension (dose-related)
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; increase risk of renal impairment. | Moderate |
| Lithium | Decreased lithium excretion, leading to lithium toxicity. | Major |
| Aliskiren (Direct Renin Inhibitor) | Increased risk of hyperkalemia, hypotension, and renal impairment, especially in diabetes/renal disease. | Major |
| Angiotensin II Receptor Blockers (ARBs: Telmisartan, Losartan) | Increased risk of hyperkalemia, hypotension, and renal impairment; use with extreme caution. | Major |
| Allopurinol, Procainamide, Immunosuppressants | Increased risk of hypersensitivity reactions, including Stevens-Johnson Syndrome. | Moderate |
| Antidiabetic drugs (Insulin, Sulfonylureas) | May enhance hypoglycemic effect. | Moderate |
| Gold injections (Sodium aurothiomalate) | Nitritoid reactions (flushing, nausea, hypotension). | Moderate |
7. Patient Counselling
- DO take the medicine at the same time each day.
- DO inform all your doctors and dentists you are on Ramipril.
- DO get regular blood tests for kidney function and potassium as advised.
- DO rise slowly from sitting or lying position to avoid dizziness.
- DONT stop taking the medicine suddenly without consulting your doctor.
- DONT take over-the-counter NSAIDs (like ibuprofen) or potassium supplements without asking your doctor.
- DONT use salt substitutes containing potassium.
8. Toxicology & Storage
Overdose: Profound hypotension, circulatory shock, bradycardia, electrolyte disturbances (hyperkalemia), acute renal failure, stupor.
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.