Beta blocking agents and calcium channel blockers
Felodipine
The FDA lists this product in 39 strengths and forms.
Indications
Felodipine extended-release tablets are indicated for the treatment of hypertension. Felodipine extended-release tablets may be used alone or concomitantly with other antihypertensive agents.
Contraindications
Felodipine extended-release tablets are contraindicated in patients who are hypersensitive to this product.
Interactions
Drug Interactions CYP3A4 Inhibitors Felodipine is metabolized by CYP3A4. Coadministration of CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, erythromycin, grapefruit juice, cimetidine) with felodipine may lead to several-fold increases in the plasma levels of felodipine, either due to an increase in bioavailability or due to a decrease in metabolism. These increases in concentration may lead to increased effects, (lower blood pressure and increased heart rate).
These effects have been observed with coadministration of itraconazole (a potent CYP3A4 inhibitor). Caution should be used when CYP3A4 inhibitors are coadministered with felodipine. A conservative approach to dosing felodipine should be taken. The following specific interactions have been reported: Itraconazole Coadministration of another extended-release formulation of felodipine with itraconazole resulted in approximately 8-fold increase in the AUC, more than 6-fold increase in the C max , and 2-fold prolongation in the half-life of felodipine.
Erythromycin Coadministration of felodipine with erythromycin resulted in approximately 2.5-fold increase in the AUC and C max , and about 2-fold prolongation in the half-life of felodipine. Grapefruit Juice Coadministration of felodipine with grapefruit juice resulted in more than 2-fold increase in the AUC and C max , but no prolongation in the half-life of felodipine. Cimetidine Coadministration of felodipine with cimetidine (a non-specific CYP-450 inhibitor) resulted in an increase of approximately 50% in the AUC and the C max , of felodipine.
Beta-Blocking Agents A pharmacokinetic study of felodipine in conjunction with metoprolol demonstrated no significant effects on the pharmacokinetics of felodipine. The AUC and C max of metoprolol, however, were increased approximately 31 and 38%, respectively. In controlled clinical trials, however, beta-blockers including metoprolol were concurrently administered with felodipine and were well tolerated. Digoxin When given concomitantly with felodipine extended-release the pharmacokinetics of digoxin in patients with heart failure were not significantly altered.



