Role of CYP2D6 and CYP3A4 polymorphisms on aripiprazole and dehydroaripiprazole concentrations in patients undergoing long-acting treatment.

Aripiprazole once-monthly (AOM) exhibits an important interindividual pharmacokinetic variability with significant implications for its clinical use. CYP2D6 and CYP3A4 highly contributes to this variability, as they metabolize aripiprazole (ARI) into its active metabolite, dehydroaripiprazole (DHA) and the latter into inactive metabolites. This study aims to evaluate the effect of CYP2D6 and CYP3A4 polymorphisms in combination and the presence of concomitant inducers and inhibitors of this cytochromes on ARI and DHA plasma concentrations in a real clinical setting. An observational study of a cohort of 74 Caucasian patients under AOM treatment was conducted. Regarding CYP2D6, higher concentrations were found for active moiety (ARI plus DHA) (AM) (67 %), ARI (67 %) and ARI/DHA ratio (77 %) for poor metabolizers (PMs) compared to normal metabolizers (NMs). No differences were found for DHA. PMs for both CYP2D6 and CYP3A4 showed a 58 % higher AM and 66 % higher plasma concentration for ARI compared with PMs for CYP2D6 and NMs for CYP3A4. In addition, PMs for both CYP2D6 and CYP3A4 have 45 % higher DHA concentrations than NMs for both cytochromes and 41 % more DHA than PMs for CYP2D6 and NMs for CYP3A4, suggesting a significant role of CYP3A4 in the elimination of DHA. Evaluating the effect of CYPD26 and CYP3A4 metabolizing state in combination on plasma concentrations of ARI, DHA and parent-to-metabolite ratio, considering concomitant treatments with inducers and inhibitor, could optimize therapy for patients under AOM treatment.

Enhancing Therapeutic Drug Monitoring in Inflammatory Bowel Disease: A Comparative Analysis of Rapid Point-of-Care Infliximab, Adalimumab and Anti-Drug Antibodies' Determination against ELISA.

The introduction of point-of-care (POC) assays into clinical practice in patients with inflammatory disease enables on-demand therapeutic decision making. The aim of this study was to compare the POC test Quantum blue (Bühlmann Laboratories) for infliximab (IFX), adalimumab (ADL), and its anti-drug antibodies with the traditional ELISA assay (Promonitor). A total of 200 serum samples were analyzed. Samples were classified into the following three different groups; sub-therapeutic range (IFX < 3 µg/mL and ADL < 5 µg/mL); therapeutic range (IFX: 3-7 µg/mL and ADL: 5-12 µg/mL) and supra-therapeutic range (IFX levels > 7 µg/mL and ADL levels > 12 µg/mL). Significant higher values were measured using the POC test (p < 0.001) for IFX results but no differences in ADL trough levels were observed (p = 0.3101). Spearman's correlation indicated a good correlation between the two assays (rs = 0.88 for ADL and rs = 0.93 for IFX), and McNemar's test revealed significant differences (p = 0.016) when classifying IFX samples between therapeutic and supra-therapeutic ranges but no significant differences were found among the other ranges for either IFX or ADL. These results show that we should be cautious when using these rapid measurement methods, and new targets should probably be defined for IFX when using this new analytical method.