Amlodipine vs Felodipine: Updated Guidance
Disclaimer: This post is intended as an educational nugget for prescribing health professionals. If, as a patient, you would like to discuss the issues raised, please consult your healthcare professional.
The UK Specialist Pharmacy Service has just published an updated comparison of amlodipine and felodipine for the treatment of hypertension or prophylaxis of stable angina. The following points are worth noting:
- For hypertension, limited data suggests that amlodipine has similar or slightly greater efficacy as an antihypertensive when compared with felodipine m/r at comparable doses. However, clinical studies comparing amlodipine with felodipine m/r in hypertension are fairly small with relatively short durations.
- There are few comparative clinical studies between amlodipine and felodipine in the treatment of stable angina. Two prospective comparison studies have shown a more favourable effect on exercise tolerance for daily felodipine m/r 10mg compared to daily amlodipine 10mg, whilst one prospective comparison study concluded that both agents (5mg daily) were equally effective. However, these trials were conducted in a very small number of patients and were of short durations.
- With respect to drug interactions, amlodipine can interact with simvastatin leading to increased risk of myopathy and rhabdomyolysis. The maximum daily dose of simvastatin should therefore not exceed 20 mg when co-administered with amlodipine. There are no restrictions for co-administration of the other statins (atorvastatin, fluvastatin, pravastatin or rosuvastatin) with amlodipine. There is currently no evidence to suggest that felodipine interacts with any of the statins.
- Published data on switching between amlodipine and felodipine in patients with hypertension or angina are limited to a few retrospective observational studies. Patients were switched from amlodipine to felodipine on a milligram-per-milligram basis. Overall, the studies showed similar effect on blood pressure, except one study which showed a significant reduction in blood pressure. Monitor for adverse effects and response.
- The decision on whether to choose amlodipine or felodipine m/r depends on a number of issues that will include local prescribing initiatives and cost, as well as efficacy, tolerability and potential drug interactions. It is important to monitor and regularly review new patients taking either drug for measures of efficacy, tolerability and safety.
Amlodipine and felodipine are dihydropyridine calcium channel blockers. The half-life of amlodipine is reported as 35 – 50 hours, which is consistent with once daily dosing. Felodipine, in the modified release (m/r) formulation has an elimination half-life of approximately 25 hours, which is also consistent with once daily dosing.
Amlodipine has a number of licensed indications. It can be used to treat hypertension, often in combination with a thiazide diuretic, angiotensin II receptor blocker, alpha blocker, beta blocker or an ACE inhibitor. Amlodipine is also licensed for the prophylaxis of stable angina pectoris and is used either as monotherapy or in combination with other antianginal drugs in patients with angina that is refractory to nitrates and/or adequate doses of beta-blockers. Amlodipine can also be used for Prinzmetal’s (variant or vasospastic) angina when diagnosed by a cardiologist. It is contraindicated in patients with unstable angina, shock or haemodynamically unstable heart failure after acute myocardial infarction.
Felodipine m/r is currently licensed for the management of hypertension and the prophylaxis of stable angina pectoris. Felodipine can be used in combination with beta-blockers, ACE inhibitors or diuretics. Felodipine is contraindicated in patients with uncontrolled heart failure or unstable angina. It should be used with caution in patients with severe left ventricular dysfunction. There are no significant pharmacological differences between the effects of amlodipine and felodipine on heart rate, myocardial contractility, cardiac output, or peripheral vascular resistance.
For further information, please refer to the SPS publication.