Current Drug Metabolism - Volume 25, Issue 6, 2024

Antibiotics and bronchodilator drugs can be used together in respiratory distress caused by bacterial infections. Levofloxacin (LVX) and Salbutamol (SLB) can be used simultaneously in respiratory distress. However, there have been no investigations on how the concurrent use of SLB can affect the pharmacokinetics of LVX in rats.

The purpose of this study was to investigate the influence of SLB on the plasma and lung pharmacokinetics of LVX in rats.

A total of 132 rats were randomly assigned to two groups: LVX (n=66) and LVX+SLB (n=66). LVX (intraperitoneal) and SLB (oral) were administered to rats at doses of 50 and 3 mg/kg, respectively. The concentrations of LVX in the plasma and lungs were determined through the utilization of high-performance liquid chromatography along with UV. Pharmacokinetic parameters were assessed by non-compartmental analysis.

The area under the curve from 0 to 16 h (AUC0−16), terminal elimination half-life, volume of distribution, total body clearance, and peak concentration of LVX in the plasma were 42.57 h*μg/mL, 2.32 h, 3.91 L/kg, 1.17 L/h/kg, and 23.96 μg/mL, respectively. There were no alterations observed in the plasma and lung pharmacokinetic parameters of LVX when co-administered with SLB. The AUC0−16 lung/AUC0−16 plasma ratios of LVX were 1.60 and 1.39 after administration alone and co-administration with SLB, respectively.

The concentration of LVX in lung tissue was higher than that in plasma. SLB administration to rats did not affect the plasma and lung pharmacokinetics and lung penetration ratio of LVX. There is a need to reveal the change in the pharmacokinetics of LVX after multiple administration of both drugs and after administration of SLB by different routes.

The ultra-short-acting benzodiazepine remimazolam, approved for procedural sedation and general anesthesia, is inactivated by carboxylesterase 1 (CES1).

Remimazolam´s involvement in CES1-mediated drug-drug interactions (DDIs) was investigated.

Possible interactions of remimazolam were studied in co-exposure experiments with eleven different drugs. Further, substrates and inhibitors of CES1, identified in the literature, were evaluated for possible in-vivo inhibition using pharmacokinetic and Ki or IC50 values. Compounds with only one published inhibitory concentration and CES1 substrates lacking inhibition data were assigned conservative Ki values.

In human liver homogenates and/or blood cells, remimazolam showed no significant inhibition of esmolol and landiolol metabolism, which, in turn, at up to 98 and 169 µM, respectively, did not inhibit remimazolam hydrolysis by human liver homogenates. In human liver S9 fractions, IC50 values ranged from 0.69 µM (simvastatin) and 57 µM (diltiazem) to > 100 µM (atorvastatin) and, for the remaining test items (bupropion, carvedilol, nelfinavir, nitrendipine, and telmisartan), they ranged from 126 to 658 µM. Remifentanil was ineffective even at 1250 µM. Guidance-conforming evaluation revealed no relevant drug-drug interactions with remimazolam via CES1. The algorithm-based predictions were consistent with human study data. Among CES1 inhibitors and substrates identified in the literature, only dapsone and rufinamide were found to be possible in-vivo inhibitors of remimazolam metabolism.

Data and analyses suggest a very low potential of remimazolam for pharmacokinetic DDIs mediated by CES1. The theoretical approach and compiled data are not specific to remimazolam and, hence, applicable in the evaluation of other CES1 substrates.

Everolimus is a drug approved for the treatment of breast cancer with HR+ and advanced breast cancer reoccurring in postmenopausal women. The oral administration of EVE has been observed to have low oral bioavailability and severe epithelial cutaneous events that include rashes and lip ulceration followed by mouth ulceration after oral administration.

The present research aimed to enhance the bioavailability by loading the EVE into a stealth liposomal formulation (S-EVE-LIPO) intended for intravenous administration.

The surface of the liposomes was modified with vitamin E TPGS, which prolongs the systemic circulation of the drug and provides additional benefits like inhibition of the P-gp efflux pump and acting synergistically with EVE.

The formulation was prepared using the thin film hydration method and optimized using a D-optimal mixture design. ANOVA suggested the significance of the proposed mathematic model, and the optimized formulation was generated by design expert software. The optimized formulation (S-EVE-LIPO) was observed with nanometric size (99.5 ± 3.70 nm) with higher encapsulation efficacy (81.5 ± 2.86%). The S-EVE-LIPO formulation indicated a sustained release profile as 90.22% drug release was observed in 48 h, whereas the formulation without vitamin E TPGS (EVE-LIPO) released only 74.15 drugs in 24 hours. In vitro cytotoxicity study suggested that the presence of vitamin E TPGS lowers the IC50 value (54.2 ± 1.69), increases the cellular uptake of the formulation, also increases the generation of ROS, and shows better hemocompatibility.

Vitamin E TPGS could be set as a vital additive to improve therapeutic efficacy and reduce off-site toxicity and dosing frequency.