Clarification of P-glycoprotein inhibition-related drug–drug interaction risks based on a literature search of the clinical information

Evaluation of the Cytochrome P450 3A and P-glycoprotein Drug-Drug Interaction Potential of Futibatinib

Futibatinib, a selective, irreversible fibroblast growth factor receptor 1-4 inhibitor, is being investigated for tumors harboring FGFR aberrations and was recently approved for the treatment of FGFR2 fusion/rearrangement-positive intrahepatic cholangiocarcinoma. In vitro studies identified cytochrome P450 (CYP) 3A as the major CYP isoform in futibatinib metabolism and indicated that futibatinib is likely a P-glycoprotein (P-gp) substrate and inhibitor. Futibatinib also showed time-dependent inhibition of CYP3A in vitro. Phase I studies investigated the drug-drug interactions of futibatinib with itraconazole (a dual P-gp and strong CYP3A inhibitor), rifampin (a dual P-gp and strong CYP3A inducer), or midazolam (a sensitive CYP3A substrate) in healthy adult participants. Compared with futibatinib alone, coadministration of futibatinib with itraconazole increased futibatinib mean peak plasma concentration and area under the plasma concentration-time curve by 51% and 41%, respectively, and coadministration of futibatinib with rifampin lowered futibatinib mean peak plasma concentration and area under the plasma concentration-time curve by 53% and 64%, respectively. Coadministration of midazolam with futibatinib had no effect on midazolam pharmacokinetics compared with midazolam administered alone. These findings suggest that concomitant use of dual P-gp and strong CYP3A inhibitors/inducers with futibatinib should be avoided, but futibatinib can be concomitantly administered with other drugs metabolized by CYP3A. Drug-drug interaction studies with P-gp-specific substrates and inhibitors are planned.

Major Bleeding Risk in Atrial Fibrillation Patients Co-Medicated With Non-Vitamin K Oral Anticoagulants and Antipsychotics

Major bleeding risks associated with non-vitamin K oral anticoagulants (NOACs) used with and without concurrent antipsychotics in patients with non-valvular atrial fibrillation (AF) were assessed. A total of 98,863 patients with non-valvular AF receiving at least one NOAC prescription from Taiwan’s National Health Insurance database were enrolled. Major bleeding was defined as a primary diagnosis of intracranial or gastrointestinal hemorrhage or bleeding at other sites. The adjusted incidence rate difference (AIRD) per 1,000 person-years and adjusted rate ratio of major bleeding were estimated using Poisson regression and inverse probability of treatment weighting using the propensity score. A total of 8,037 major bleeding events occurred during 705,521 person-quarters with NOAC prescriptions. Antipsychotics were used in 26.35% of NOAC-exposed patients. Compared to using NOAC alone, co-medication of either typical (AIRD: 79.18, 95% confidence interval [CI]: 70.63–87.72) or atypical (AIRD: 40.5, 95% CI: 33.64–47.35) antipsychotic with NOAC had a significant increase in the adjusted incidence rate per 1,000 person-years of major bleeding. The concomitant use of a NOAC with chlorpromazine (AIRD: 103.87, 95% CI: 51.22–156.52), haloperidol (AIRD: 149.52, 95% CI: 125.03–174.00), prochlorperazine (AIRD: 90.43, 95% CI: 78.55–102.32), quetiapine (AIRD: 44.6, 95% CI: 37.11–52.09), or risperidone (AIRD: 41.55, 95% CI: 22.86–60.24) (All p < 0.01) showed a higher adjusted incidence rate of major bleeding than using NOACs alone. The concomitant use of typical (chlorpromazine, haloperidol, or prochlorperazine) or atypical (quetiapine or risperidone) antipsychotic with NOACs was associated with a significantly increased risk of major bleeding.

No evidence for interactions of dimethylfumarate (DMF) and its main metabolite monomethylfumarate (MMF) with human cytochrome P450 (CYP) enzymes and the P-glycoprotein (P-gp) drug transporter

Dimethylfumarate (DMF) has long been used as part of a fixed combination of fumaric acid esters (FAE) in some European countries and is now available as an oral monotherapy for psoriasis. The present investigation determined whether DMF and its main metabolite monomethylfumarate (MMF) interact with hepatic cytochrome P450 (CYP) enzymes and the P-glycoprotein (P-gp) transporter, and was performed as part of DMF's regulatory commitments. Although referred to in the available product labels/summary of product characteristics, the actual data have not yet been made publicly available. In vitro inhibition experiments using CYP-selective substrates with human liver microsomes showed 50% inhibitory concentrations (IC50) of >666 µmol/L for DMF and >750 µmol/L for MMF. MMF (≤250 μmol/L; 72 hours) was not cytotoxic in cultured human hepatocyte experiments and mRNA expression data indicated no CYP induction by MMF (1-250 µmol/L). DMF (≤6.66 mmol/L) showed moderate-to-high absorption (apparent permeability [Papp] ≥2.3-29.7 x 10-6 cm/s) across a Caucasian colon adenocarcinoma (Caco-2) cell monolayer, while MMF (≤7.38 mmol/L) demonstrated low-to-moderate permeability (Papp 1.2-8.9 × 10-6 cm/s). DMF was not a substrate for P-gp (net efflux ratios ≤1.22) but was a weak inhibitor of P-gp at supratherapeutic concentrations (estimated IC50 relative to solvent control of 1.5 mmol/L; [3H]digoxin efflux in Caco-2 cells). This inhibition is unlikely to be clinically relevant. MMF was not a substrate or inhibitor of P-gp. Thus, DMF and MMF should not affect the absorption, distribution, metabolism or excretion of coadministered drugs that are CYP and P-gp substrates.

The clinical significance of statins-macrolides interaction: comprehensive review of in vivo studies, case reports, and population studies

The objectives of this article were to review the mechanism and clinical significance of statins-macrolides interaction, determine which combination has the highest risk for the interaction, and identify key patients' risk factors for the interaction in relation to the development of muscle toxicity. A literature review was conducted in PubMed and Embase (1946 to December 2018) using combined terms: statins - as group and individual agents, macrolides - as group and individual agents, drug interaction, muscle toxicity, rhabdomyolysis, CYP3A4 inhibitors, and OAT1B inhibitors, with forward and backward citation tracking. Relevant English language in vivo studies in healthy volunteers, case reports, and population studies were included. The interaction between statins and macrolides depends on the type of statin and macrolide used. The mechanism of the interaction is due to macrolides' inhibition of CYP3A4 isoenzyme and OAT1B transporter causing increased exposure to statins. The correlation of this increased statin's exposure to the development of muscle toxicity could not be established, unless the patient had other risk factors such as advanced age, cardiovascular diseases, renal impairment, diabetes, and the concomitant use of other CYP3A4 inhibitors. Simvastatin, lovastatin, and to lesser extent atorvastatin are the statins most affected by this interaction. Rosuvastatin, fluvastatin, and pravastatin are not significantly affected by this interaction. Telithromycin, clarithromycin, and erythromycin are the most "offending" macrolides, while azithromycin appears to be safe to use with statins. This review presented a clear description of the clinical significance of this interaction in real practice. Also, it provided health care professionals with clear suggestions and recommendations on how to overcome this interaction. In conclusion, understanding the different characteristics of each statin and macrolide, as well as key patients' risk factors, will enable health care providers to utilize both groups effectively without compromising patient safety.

Comparative pharmacokinetics study of anastrozole after single administration and combination with celecoxib

1. There are numerous investigations demonstrating that the cyclooxygenase-2 (COX-2) inhibitors might enhance the efficiency of anastrozole in breast cancer. Hence, this study was conducted to investigate the comparative pharmacokinetics of anastrozole after single administration and combination with celecoxib. 2. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recovery for both anastrozole and the internal standard, and then anastrozole was separated and analysed on an ACQUITY BEH UPLC C₁₈ column (50 × 2.0 mm, 1.7 μm, Waters) within 2 min. The calibration curves showed good linarites (r = 0.994). Intra- and inter-day precision were within 4.93 and 13.83%, respectively. The mean extraction recoveries across QC levels were within 91.4%, and the matrix effects were within 94.5%. 3. Results showed that the method was reliable to determine anastrozole in rat plasma. Compared with rats in single administration group, no significant difference was found in the combination group. It is workable to use celecoxib combined with anastrozole in clinical therapy.

Prediction of drug-ABC-transporter interaction--Recent advances and future challenges

With the discovery of P-glycoprotein (P-gp), it became evident that ABC-transporters play a vital role in bioavailability and toxicity of drugs. They prevent intracellular accumulation of toxic compounds, which renders them a major defense mechanism against xenotoxic compounds. Their expression in cells of all major barriers (intestine, blood–brain barrier, blood–placenta barrier) as well as in metabolic organs (liver, kidney) also explains their influence on the ADMET properties of drugs and drug candidates. Thus, in silico models for the prediction of the probability of a compound to interact with P-gp or analogous transporters are of high value in the early phase of the drug discovery process. Within this review, we highlight recent developments in the area, with a special focus on the molecular basis of drug–transporter interaction. In addition, with the recent availability of X-ray structures of several ABC-transporters, also structure-based design methods have been applied and will be addressed.