Prediction of drug-drug interaction risk of P-glycoprotein substrate in drug discovery

Minimal Involvement of P-gp and BCRP in Oral Absorption of Ensitrelvir, An Oral SARS-CoV-2 3C-like Protease Inhibitor, in a Non-Clinical Investigation

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are important transporters causing drug-drug interaction (DDI). Here, we investigated the involvement of P-gp and BCRP in the oral absorption of ensitrelvir in non-clinical studies and estimated the DDI risk mediated by P-gp and BCRP inhibition in humans. Although ensitrelvir is an in vitro P-gp and BCRP substrate, it demonstrated high bioavailability in rats and monkeys after oral administration. Plasma exposures of ensitrelvir following oral administration were comparable in wild type (WT) and Bcrp (-/-) mice. On the other hand, the area under the plasma concentration-time curve (AUC) ratio of ensitrelvir in the Mdr1a/1b (-/-) mice to the WT mice was 1.92, indicating that P-gp, but not BCRP, was involved in the oral absorption of ensitrelvir. Based on our previous retrospective analyses, such a low AUC ratio (<3) in the Mdr1a/1b (-/-) mice indicates a minimal impact of P-gp on the oral absorption in humans. In conclusion, our studies demonstrate that the involvement of both P-gp and BCRP in the oral absorption of ensitrelvir is minimal, and suggest that ensitrelvir has a low risk for DDIs mediated by P-gp and BCRP inhibition in humans.

Study on the uptake of Gastrodin in the liver

Background

Gastrodin is the active monomer of the Chinese herb Rhizoma Gastrodiae with the largest quantity of active components. Gastrodin is commonly used in the treatment of central nervous system disorders such as headaches and epilepsy due to its sedating and hypnotic properties. Its pharmacological mechanism and clinical application have been extensively explored due to its low toxicity.

Methods

To investigate the molecular mechanism of hepatic uptake of Gastrodin in rats, animals were randomly assigned to three groups: control group, rifampicin (RIF) group, and adrenalone (ADR) group. Blood samples were collected through the cardiac puncture 90, 180, and 300 min after injection, respectively. Rats were sacrificed 300 min after administration, and liver tissue was collected. Gastrodin concentration was determined by HPLC, and the Kp value was calculated.

Results

After administering the inhibitors of organic cation transporters (OCTs) and organic anion transporting polypeptides (OATPs), the KP values in the experimental groups were significantly lower compared to the blank control group (P < 0.05).

Conclusions

These findings imply that Gastrodin may be a substrate for both OCTs and OATPs.