Ritonavir Fexofenadine

C2CI2O2 79-37-8) see Cefuroxime Diclofenae Dorzolamide Fexofenadine hydroehloride Granisetron Gusperimus trihydrochloride Indoramin Maprotiline Micinicate Ritonavir Saquinavir Sumatriptan Tacrolimus Tirofiban hydrochloride Tropisetron Viminol... 

Perloff MD, von Moltke LL, Greenblatt DJ (2002) Fexofenadine transport in Caco-2 cells Inhibition with verapamil and ritonavir. J Clin Pharmacol 42 1269-1274. 

Drug-drug interactions involving fexofenadine have been reported which includes not only interactions with concomitant chugs, but also those with fruit juices. Concomitant use of itraconazole (303), verapamil (304), and ritonavir (305) increased the area under the curve of the plasma concentration (AUC) and peak plasma concentration (Cmax) of fexofenadine following oral administration, but did not affect the elimination half-life. Itraconazole and verapamil did not affect the renal clearance of fexofenadine, while the effect of ritonavir on the renal clearance was not examined. Considering the absence of the effect on the renal clearance, these interactions will include the inhibition of intestinal... 

Nelflnavir markedly increases terfenadine levels, which is expected to increase the risk of QT prolongation and torsade de pointes arrhythmias. Other protease inhibitors are predicted to interact similarly with both terfenadine and astemizole, and concurrent use Is contraindicated. Ritonavir modestly increases cetirizine levels, and in vitro data suggests that saquinavir will have a similar effect, but this Is not considered to be clinically relevant. Based on in vitro data, ritonavir is predicted to markedly raise fexofenadine levels, but this may not be of any clinical relevance. 

An in vitro study showed that ritonavir markedly reduced the transport of fexofenadine, thought to be via inhibition of P-glycoprotein. This would be predicted to markedly increase the bioavailability of fexofenadine, as occurs with verapamil, see Calcium-channel blockers + Antihistamines , p.861. However, the similar marked increases in fexofenadine levels that occurred with erythromycin , (p.589) and ketoconazole , (p.584) did not increase adverse effects and were not associated with any prolongation of the QT interval. This suggests that a clinically relevant interaction between ritonavir and fexofenadine is not expected. 

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