Drug-Drug Interaction Between Eugenol and Repaglinide in Type 2 Diabetes Mellitus and Its Potential Mechanism

Summary

This study aimed to explore potential drug-drug interactions between eugenol (EUG) and repaglinide (RPG) in patients with type 2 diabetes mellitus (T2DM).

Abstract

This study investigated the potential drug-drug interaction (DDI) between eugenol (EUG) and repaglinide (RPG) in type 2 diabetes mellitus (T2DM). A T2DM rat model was established using a high-fat diet and streptozotocin (STZ). The single-dose group received 0.4 mg/kg RPG, and co-administration groups were pre-treated with EUG (50, 100, 150 mg/kg) for seven days before receiving a single dose of RPG (0.4 mg/kg). The blood glucose and pharmacokinetic parameters of RPG were assessed in the plasma samples of rats. The effect of EUG on RPG metabolic stability and cytochrome P3A (CYP3A) activity was evaluated in rat liver microsomes (RLM). In T2DM rats, RPG treatment showed a hypoglycemic effect, which was further promoted by EUG co-administration in a dose-dependent manner (p < 0.001). EUG co-administration affected the pharmacokinetics of RPG by increasing the area under the curve (AUC, increased 88.64%, 164.59%, and 244.72% vs single RPG, p < 0.001), plasma maximum concentration (C_max, increased 18.61%, 53.58%, and 77.63% vs single RPG, p < 0.01), maximum concentration (T_max, 1.0 h for EUG co-administration vs 0.5 h for single RPG), half-life (t_1/2, prolonged 33.86%, 49.61%, and 88.19% vs single RPG, p < 0.01), mean retention time (MRT, prolonged 17.62%, 26.42%, 44.04% vs single RPG, p < 0.001), and decreased the clearance rate (Clz/F, decreased 48.92%, 63.31%, and 74.10% vs single RPG, p < 0.001) in a dose-dependent manner. In vitro RLM study, EUG improved the metabolic stability of RPG by prolonging the half-life (44.09 ± 3.25 min) and reducing the intrinsic clearance (30.55 ± 3.69 µL/min/mg protein). EUG also inhibited the activity of CYP3A with an IC₅₀ of 7.90 ± 1.79 µM. Co-administration of EUG promoted the hypoglycemic effect of RPG through enhancing RPG systemic exposure in T2DM rats, potentially by improving RPG metabolic stability and inhibiting CYP3A activity.

Introduction

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance or reduced insulin efficiency, which affects millions of individuals worldwide¹. Complex interactions with genetic susceptibility and lifestyle factors are involved in T2DM, resulting in impaired glucose uptake, excessive hepatic gluconeogenesis, and chronic low-grade inflammation². T2DM can lead to serious complications if treated improperly, including cardiovascular diseases, kidney disease, retinopathy, and neuropathy, significantly affecting the patients’ life quality and increasing mortality²

Protocol

This study was approved by the Jilin Academy of Chinese Medical Sciences Ethics Committee (Date:2024.11.21/No.2024112) in compliance with the ARRIVE guidelines²⁸. The reagents and the equipment used are listed in the Table of Materials.

1. Animal housing conditions

Male Sprague-Dawley rats (200–250 g) were housed in a laboratory animal room under the following conditions: temperature: 22 °C ± 2 °C, relative humidity: 40–60%, and a 12-h light/dark cycle, with free access to food and water to allow one week of acclimatization

Results

EUG promoted the hypoglycemic effect of RPG in T2DM rats
The blood glucose level of the rats in the T2DM group was increased (p < 0.001, 95% CI: -13.90~-11.32) in comparison with that of the control group, indicating the successful conduction of the T2DM model (Figure 1A). Administration of a single RPG suppressed the blood glucose level in the T2DM rats (p < 0.001, 95% CI: 5.26~7.84). Co-administration of RPG and EUG further decreased the glucose.......

Discussion

T2DM is a chronic metabolic disease that requires long-term treatment, and patients often need to take multiple medications due to underlying conditions such as cardiovascular disease and kidney disease³². The risk of DDIs significantly increases with drug co-administration, as it may affect the absorption, metabolism, or efficacy of hypoglycaemic drugs, which can lead to acute risks such as hypoglycaemic coma and uncontrolled blood sugar levels³³. It may also exacerbate or.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
acetonitrile	Merck, Germany	34851	≥99.9%
chromatographic column	Phenomenex, USA	00G-4041-E0	250 mm × 4.6 mm, particle size 5 μm
DAS	Beijing Bozhiyin, China	-	3.0
EUG	MUST Bio-technology, China	A0074	purity ≥99%
GraphPad Prism	GraphPad Software, USA	-	9.0.0
High Performance Liquid Chromatography	Shimadzu Corporation, Japan	228-45147-42	RF-20A
ketoconazole	Merck, Germany	K1003	Purity 99.0-101.0%
Male Sprague-Dawley rats	Shanghai Animal Center, China	-	200–250 g
NADPH	Merck, Germany	10107824001	97% (dry weight)
OneTouch Ultra2 blood glucose meter	Life Scan Inc., USA	https://shop.onetouch.com/onetouch-sup-reg-sup-ultra-sup-reg-sup-2-meter/product/OTSUS05_0019	-
PBS	Merck, Germany	P4474	ph 7.4
RLM	Merck, Germany	M9066	-
RPG	Merck, Germany	R9028	purity ≥98%
STZ	Merck, Germany	S0130	≥98% (HPLC)
EUG, eugenol; RPG, repaglinide; RLM, rat liver microsomes; NADPH, β-Nicotinamide adenine dinucleotide phosphate; STZ, streptozotocin; PBS, phosphate-buffered saline.