Case Study 5: Predicting the Drug Interaction Potential for Inhibition of CYP2C8 by Montelukast.

Predicting drug-drug interactions (DDIs) from in vitro data is made difficult by not knowing concentrations of substrate and inhibitor at the target site. For in vivo targets, this is understandable, since intracellular concentrations can differ from extracellular concentrations. More vexing is that the concentration of the drug at the target for some in vitro assays can also be unknown. This uncertainty has resulted in standard in vitro practices that cannot accurately predict human pharmacokinetics. This case study highlights the impact of drug distribution, both in vitro and in vivo, with the example of the drug interaction potential of montelukast.

A Combined Self-Assembled Drug Delivery for Effective Anti-Breast Cancer Therapy.

AIM: The metastasis of breast cancer is an important cause of tumor recurrence. This study highlights that tyrosine kinase inhibitors dasatinib (DAS) and rosiglitazone (ROZ) inhibit tumor growth and reduce the occurrence of tumor cell metastasis. Due to the poor water solubility, short half-time in the body of DAS and ROZ, which increases the difficulty of tumor treatment, as well as the demand for nano-drug delivery systems for organ-specific therapies. METHODS: Hyaluronic acid (HA) and DAS are bonded by a pH-sensitive ester bond to form an HA-DAS polymer. Then, ROZ was added as the core, D-A-tocopherol polydiethylene glycol isosuccinate (TPGS) and HA-DAS were used as carriers to form HA-DAS and TPGS mixed micelle system loaded with ROZ (THDR-NPs). The size and structure of THDR-NPs were characterized, the drug release, stability and biosafety of THDR-NPs were studied. In vitro, the cytotoxicity, targeting effect and tumor metastasis inhibition of THDR-NPs were evaluated in human breast cancer cell lines. In addition, the selective potency of designed THDR-NPs in depleting was further verified in vivo in the tumor-bearing nude mice model. RESULTS: The designed THDR-NPs have a particle size of less than 100 nm, good stability, biological safety and sustained release, and showed strong therapeutic effects on breast cancer models in vitro and in vivo. Moreover, it has been proved that THDR-NPs have the ability to inhibit tumor metastasis. CONCLUSION: DAS and ROZ were designed into micelles, the efficacy of THDR-NPs was higher than that of free drugs. These results indicate that nanoparticles have a good application prospect in the treatment of tumor metastasis.

Ultrasound Assisted a Peroxisome Proliferator-Activated Receptor (PPAR)γ Agonist-Loaded Nanoparticle-Microbubble Complex to Attenuate Renal Interstitial Fibrosis.

OBJECTIVE: To investigate the antifibrotic effect of the combination of a PPARγ agonist-loaded nanoparticle-microbubble complex with ultrasound (US) exposure on renal interstitial fibrosis (RIF). MATERIALS AND METHODS: Polylactide-co-glycolide (PLGA) nanoparticles were used to load PPARγ agonist (rosiglitazone, RSG) and prepare PLGA-RSG nanoparticles (PLNPs-RSG); then, a novel complex between PLNPs-RSG and SonoVue microbubbles (MBs) (PLNPs-RSG-MBs) was prepared. The size distribution, zeta potentials, RSG-loading capacity and entrapment efficiency were measured, and the release of RSG was assessed using a UV-vis spectrophotometer. The in vitro cytotoxicity and in vivo systemic toxicity assays were performed. The cellular uptake assessment was performed using a confocal laser scanning microscope (CLSM). The in vivo biodistribution assessment was performed using fluorescence imaging with a near-infrared (NIR) imaging system. Furthermore, this complex was administered to a unilateral ureteral obstruction (UUO) rat model with the assistance of US exposure to investigate the antifibrotic effect. RESULTS: This PLNPs-RSG-MBs complex had a size of 2199.5± 988.1 nm and a drug-loading efficiency of 28.5%. In vitro cytotoxicity and in vivo systemic toxicity assays indicated that the PLNPs-RSG-MBs complex displayed excellent biocompatibility. In addition, the complex showed high cellular uptake efficiency in vitro and kidney-targeting ability in vivo. In a UUO rat model, the combination of the PLNPs-RSG-MBs complex with US exposure significantly reduced collagen deposition and successfully attenuated renal fibrosis. CONCLUSION: The combination of the PLNPs-RSG-MBs complex with US exposure may be a promising approach for the treatment of RIF.

Lack of inhibition of CYP2C8 by saroglitazar magnesium: In vivo assessment using montelukast, rosiglitazone, pioglitazone, repaglinide and paclitaxel as victim drugs in Wistar rats.

Saroglitazar, a PPAR αÒ® agonist, is currently undergoing global development for the treatment of NASH and other indications. Saroglitazar showed CYP2C8 inhibition in human liver microsomes (IC50: 2.9 µM). The aim was to carry out drug-drug interaction (DDI) studies in Wistar rats using saroglitazar (perpetrator drug) with five CYP2C8 substrates. Also, the in vitro CYP2C8 inhibitory potential of saroglitazar in rat liver microsomes (RLM) was evaluated to justify use of preclinical model. The oral pharmacokinetics of various CYP2C8 substrates; montelukast, rosiglitazone, pioglitazone, repaglinide and intravenous pharmacokinetics of paclitaxel was assessed in the presence/absence of oral saroglitazar (4 mg/kg) in Wistar rats. A separate study was performed to assess the oral pharmacokinetics of saroglitazar. Serial blood samples were collected from all studies and the harvested plasma were stored frozen until bioanalysis. LC-MS/MS was used for the analysis of various analytes; concentration data was subjected to noncompartmental pharmacokinetic analysis. Statistical tests (unpaired t-test) were employed to judge the level of DDI. Generally, the pharmacokinetics of CYP2C8 substrates was not affected by the concomitant intake of saroglitazar as judged by the overall exposure (AUC0-last and AUC0-inf) and elimination half-life. The CYP2C8 IC50 of 4.5 µM in RLM for saroglitazar, supported the use of rats for this DDI study. In conclusion, pharmacokinetic data of diverse CYP2C8 substrates suggested that coadministration of saroglitazar did not cause clinically relevant DDI.

Lack of Impact by SCY-078, a First-in-Class Oral Fungicidal Glucan Synthase Inhibitor, on the Pharmacokinetics of Rosiglitazone, a Substrate for CYP450 2C8, Supports the Low Risk for Clinically Relevant Metabolic Drug-Drug Interactions.

SCY-078, the first in a new class of ß 1,3-glucan synthesis inhibitors, is being developed as an oral and intravenous antifungal treatment for Candida and Aspergillus species fungal infections. In vitro, studies indicated SCY-078 is an inhibitor of cytochrome P450 (CYP) 2C8 with markedly lower effect over other CYP isozymes. To examine clinically relevant effects of the potential interaction with SCY-078, this phase 1, open-label, 2-period crossover study evaluated the pharmacokinetic parameters of rosiglitazone, a sensitive substrate of CYP2C8 metabolism, in the absence and presence of SCY-078 dosed to therapeutically relevant SCY-078 concentration exposure after repeat dosing. Healthy adult subjects were randomized to 2 treatment sequences: a single oral 4-mg rosiglitazone dose alone on day 1 or a 1250-mg SCY-078 loading dose on day 1 followed by a once-daily 750-mg SCY-078 dose for an additional 7 days (reflecting the clinical regimen evaluated during phase 2 studies for infections by Candida species) and concurrent administration of a single oral 4-mg rosiglitazone dose on day 3, before alternating following a ≥10-day washout. The exposure to SCY-078 observed in this study was in line with the intended exposure for treatment of invasive fungal infections. The 90% confidence intervals for rosiglitazone exposure geometric mean ratios were within the prespecified no effect interval of 0.70-1.43. Additionally, maximum concentration values for rosiglitazone and its metabolite, N-desmethylrosiglitazone, were not significantly affected by co-administration with SCY-078. Overall, rosiglitazone exposure was not impacted to a clinically meaningful extent with co-administration of therapeutically relevant SCY-078 concentration exposure after repeat dosing. The results are indicative of low risk for interaction of SCY-078 with drugs metabolized via the CYP family of enzymes.