Coadministration of ritonavir either simultaneously or 6 h later than afatinib 40 mg resulted in minimal increase in the afatinib gMean C max and AUC ( 4.1 and 18.6 % for simultaneous administration with AUC not completely within the bioequivalence limits ; 5.1 and 10.8 % for timed administration within the bioequivalence limits ) .