Development, physicochemical evaluation, and in vivo permeation studies of topical formulations containing 0.1% tacrolimus

Abstract The objective of this paper was to develop and evaluate two semi-solid pharmaceutical forms containing 0.1% tacrolimus: cream (CRT01) and gel (GLT01). For the evaluation of physicochemical stability, at times 0, 30, 60 and 90 days, at 23°C and at 40°C, High Performance Liquid Chromatography coupled with a Diode Array Detector (HPLC-DAD) was employed. This method was developed and validated for tacrolimus quantification. The occlusivity test and skin permeation assay were also performed, using an animal model (Wistar rats), and the CRT01 and GLT01 were compared to the 0.1% tacrolimus ointment (PFU01) obtained from the University Pharmacy, Federal University of Rio de Janeiro, Brazil. CRT01 and GLT01 presented a homogeneous aspect and consistency adequate for topical products, along with sensory characteristics above PFU01. They also presented adequate physicochemical stability for 90 days and a lower occlusive effect than PFU01 (p<0.05). CRT01 showed greater affinity for the skin when compared to PFU01 and GLT01, with low systemic absorption. The CRT01 semi-solid formulation was considered the most adequate one to treat patients with atopic dermatitis or other dermatologic inflammatory diseases, promoting rational use of tacrolimus

Prediction of the Impact of CYP2C19 Polymorphism on Drug-Drug Interaction between Voriconazole and Tacrolimus Using Physiologically-Based Pharmacokinetic Modelling

Abstract Voriconazole increases tacrolimus blood concentration significantly when coadministrated. The recommendation of reducing tacrolimus to 1/3 in voriconazole package insert seems not to be satisfactory in clinical practice. In vitro studies demonstrated that the magnitude of inhibition depends on the concentration of voriconazole, while voriconazole exposure is determined by the genotype status of CYP2C19. CYP2C19 gene polymorphism challenges the management of drug-drug interactions(DDIs) between voriconazole and tacrolimus. This work aimed to predict the impact of CYP2C19 polymorphism on the DDIs by using physiologically based pharmacokinetics (PBPK) models. The precision of the developed voriconazole and tacrolimus models was reasonable by evaluating the pharmacokinetic parameters fold error, such as AUC0-24, Cmax and tmax. Voriconazole increased tacrolimus concentration immediately in all population. The simulated duration of DDIs disappearance after voriconazole withdrawal were 146h, 90h and 66h in poor metabolizers (PMs), intermediate metabolizers (IMs) and extensive metabolizers(EMs), respectively. The developed and optimized PBPK models in this study can be applied to assit the dose adjustment for tacrolimus with and without voriconazole.