| Lercanidipine is known to be metabolised by the CYP3A4 enzyme and, therefore, inhibitors and inducers of CYP3A4 administered concurrently may interact with the metabolism and elimination of lercanidipine.Co-prescription of Lercanidipine HCl with inhibitors of CYP3A4 (e.g. ketoconazole itraconazole, ritonavir, erythromycin, troleandomycin) should be avoided (see 4.3). An interaction study with a strong CYP3A4 inhibitor, ketoconazole, has shown a considerable increase in plasma levels of lercanidipine (a 15-fold increase of the AUC and an 8-fold increase of the Cmax for the eutomer S-lercanidipine). Cyclosporin and lercanidipine should not be administered together (see 4.3).Increased plasma levels of both lercanidipine and cyclosporin have been observed following concomitant administration. A study in young healthy volunteers has shown that when cyclosporin was administered 3 hours after the lercanidipine intake, the plasma levels of lercanidipine did not change, while the AUC of cyclosporin increased by 27%. However, the co-administration of Lercanidipine HCl with cyclosporin has caused a 3-fold increase of the plasma levels of lercanidipine and a 21% increase of the cyclosporin AUC.Lercanidipine should not be taken with grapefruit juice (see 4.3).As for other dihydropyridines, lercanidipine is sensitive to inhibition of metabolism by grapefruit juice, with a consequent rise in its systemic availability and increased hypotensive effect.When concomitantly administered at a dose of 20 mg with midazolam p.o. to elderly volunteers, lercanidipine's absorption was increased (by approximately 40%) and the rate of absorption was decreased (tmax was delayed from 1.75 to 3 hours). Midazolam concentrations were not modified.Caution should be exercised when Lercanidipine HCL is co-prescribed with other substrates of CYP3A4, like terfenadine, astemizole, class III antiarrhythmic drugs such as amiodarone, quinidine. Co-administration of Lercanidipine HCl with CYP3A4 inducers like anticonvulsants (e.g.phenytoin, carbamazepine) and rifampicin should be approached with caution since the antihypertensive effect may be reduced and blood pressure should be monitored more frequently than usual. When Lercanidipine HCl was co-administered with metoprolol, a β-blocker eliminated mainly by the liver, the bioavailability of metoprolol was not changed while that of lercanidipine was reduced by 50%. This effect may be due to the reduction in the hepatic blood flow caused by β-blockers and may therefore occur with other drugs of this class. Consequently, lercanidipine may be safely administered with beta-adrenoceptor blocking drugs, but dose adjustment may be required.An interaction study with fluoxetine (an inhibitor of CYP2D6 and CYP3A4), conducted in volunteers of an age of 65 ± 7 years (mean ± s.d.), has shown no clinically relevant modification of the pharmacokinetics of lercanidipine.Concomitant administration of cimetidine 800 mg daily does not cause significant modifications in plasma levels of lercanidipine, but at higher doses caution is required since the bioavailability and the hypotensive effect of lercanidipine may be increased.Co-administration of 20 mg lercanidipine in patients chronically treated with β-methyldigoxin showed no evidence of pharmacokinetic interaction. Healthy volunteers treated with digoxin following dosing with 20 mg lercanidipine given fasted showed a mean increase of 33% in digoxin Cmax, while AUC and renal clearance were not significantly modified. Patients on concomitant digoxin treatment should be closely monitored clinically for signs of digoxin toxicity.When a dose of 20 mg of Lercanidipine HCl was repeatedly co-administered with 40 mg of simvastatin, the AUC of lercanidipine was not significantly modified, while simvastatin's AUC increased by 56% and that of its active metabolite β-hydroxyacid by 28%. It is unlikely that such changes are of clinical relevance. No interaction is expected when lercanidipine is administered in the morning and simvastatin in the evening, as indicated for such drug. The co-administration of 20 mg lercanidipine to healthy volunteers given fasted did not alter the pharmacokinetics of warfarin.Lercanidipine HCl has been safely administered with diuretics and ACE inhibitors.Alcohol should be avoided since it may potentiate the effect of vasodilating antihypertensive drugs (see 4.4). | |