Drug interactions of tacrolimus with letermovir and azole antifungals following hematopoietic stem cell transplantation: A retrospective observational analysis.

Tacrolimus interacts with letermovir and azole antifungals, whereas letermovir has nonuniform effects on the pharmacokinetics of azole antifungals. We retrospectively investigated the interaction of tacrolimus (continuous infusion) with letermovir considering co-administered azole antifungals in adult hematopoietic stem cell transplantation patients. The extent of intraindividual variation in the ratio of tacrolimus concentration to dose normalized by body weight (C/D ratio) was investigated. The correlation between the C/D ratio and estimated glomerular filtration rate (eGFR) was analyzed. In 35 patients (795 points), the C/D ratio was higher in the tacrolimus plus letermovir period than in the tacrolimus alone period (1234.7 [566.2-2721.0] ng/mL/mg/kg vs. 564.4 [245.3-1861.3] ng/mL/mg/kg, p < .001). This trend was observed when co-administered with azole antifungals (n = 30, 1285.5 [662.7-2506.7] ng/mL/mg/kg vs. 547.1 [245.3-1861.3] ng/mL/mg/kg, p < .001), but not without azole antifungals (n = 5, 809.9 [566.2-1573.3] ng/mL/mg/kg vs. 616.1 [350.6-979.8] ng/mL/mg/kg, p = .125). For patients co-administered fluconazole, the tacrolimus C/D ratio increased in patients with letermovir than those without letermovir (n = 28, 1215.0 [662.7-2506.7] ng/mL/mg/kg vs. 529.9 [245.3-1654.4] ng/mL/mg/kg, p < .001). Tacrolimus C/D ratio did not correlate with eGFR under letermovir and fluconazole administrations (y = 0.1x + 1307.1, r = .008, p = .968). Close blood concentration monitoring of intravenous tacrolimus is required when patients administered letermovir and azole antifungals.

Evaluation of bleeding and anticoagulation markers by edoxaban and low-dose cyclosporine: A case series study.

It was reported that high-dose cyclosporine at 500 mg daily increases edoxaban exposure. We investigated whether cyclosporine <500 mg daily leads to edoxaban-induced bleeding in the clinical setting. This case series study included patients receiving edoxaban and cyclosporine at Mie University Hospital. The outcomes were bleeding and anticoagulant markers, including activated partial thromboplastin time (APTT), prothrombin time (PT), and the international normalized ratio of prothrombin time (PT-INR). We examined the genotypes of cytochrome P450 3A5 (CYP3A5), multidrug resistance 1 (ABCB1), and solute carrier organic anion transporter 1B1 (SLCO1B1). Trends in anticoagulant markers were analyzed. Thirteen patients received edoxaban (standard dose; n = 3 and reduced dose; n = 10) and cyclosporine (1.94 ± 1.42 mg/kg). A bleeding event occurred in one patient receiving a standard dose of edoxaban plus cyclosporine of 25 mg daily (HAS-BLED score of 2 and genotypes; CYP3A5*3/*3, ABCB1 3435CT, and SLCO1B1*1a/*1b). After edoxaban treatment, anticoagulant markers were prolonged (APTT; 27.95 ± 3.64 s vs. 31.11 ± 3.90 s, p < 0.001, PT; 11.53 ± 1.01 s vs. 13.03 ± 0.98 s, p = 0.002, PT-INR; 0.98 ± 0.09 vs. 1.11 ± 0.11, p = 0.007). In summary, the genotypes of CYP3A5, ABCB1, and SLCO1B1 and the dosage of edoxaban may affect the risk of bleeding by edoxaban when co-administered with cyclosporine, even at low doses.

Concomitant febuxostat enhances methotrexate-induced hepatotoxicity by inhibiting breast cancer resistance protein.

Methotrexate (MTX) is an antifolate agent used for the treatment of various malignancies and is eliminated by breast cancer resistance protein (BCRP). Because febuxostat (FBX) is known to inhibit BCRP activity, FBX might exacerbate MTX-related adverse effects. In this study, we examined the drug-drug interaction between FBX and MTX in BCRP-expressing membrane vesicles. Moreover, we retrospectively investigated the impact of FBX on MTX-related adverse effects in 38 patients (144 cycles) receiving high-dose MTX therapy (HDMTX). The Food and Drug Administration Adverse Event Reporting System (FAERS) database and human hepatocellular carcinoma cell line HepG2 cells were used to evaluate the effects of FBX on MTX-induced hepatotoxicity. In the membrane vesicle study, FBX significantly inhibited BCRP-mediated transport of MTX. Concomitant FBX significantly increased the incidence of hepatotoxicity, but not of nephrotoxicity and hematological toxicity in patients receiving HDMTX. FAERS database analyses revealed that the reporting odds ratio of FBX for MTX-induced hepatotoxicity was 4.16 (95% CI: 2.89-5.98). Co-incubated FBX significantly decreased the cell viability and increased cytotoxicity in MTX-treated HepG2 cells. These findings suggest that concomitant FBX enhances MTX-induced hepatotoxicity by inhibiting hepatic BCRP. These findings provide important information for the safe management of HDMTX therapy in clinical settings.