In situ intestinal absorption and pharmacokinetic study of metformin-resveratrol compound water-in-oil nanoemulsion

To investigate the in situ intestinal absorption characteristics and pharmacokinetic behavior of metformin-resveratrol compound water-in-oil nanoemulsion (MRCE) in rats, the in situ intestinal perfusion model was constructed in rats to study the intestinal absorption characteristics of MRCE in different intestinal segments. Male Sprague-Dawley rats were randomly divided into two groups. After intragastric administration of metformin and MRCE, blood was taken at a preset time point. The content of metformin in intestinal perfusion samples and blood samples at various time points was determined by HPLC. Plasma concentration-time profiles of free metformin and MRCE were calculated, and the main pharmacokinetic data were processed and analyzed by DAS 2.1.1 software. The absorption rate constant (K_a), the effective permeability (P_eff) and the percentage of absorption (PA) of MRCE in each intestinal segment were significantly higher than those of metformin (P < 0.05). The area under the drug-time curve (AUC_{0-72 h}), the half-life (t_1/2) and mean residence time (MRT_{0-72 h}) of MRCE were 1.68, 11.25 and 6.97 times of metformin, respectively (P < 0.01).The relative bioavailability of MRCE was 167.6%. The 90% confidence interval of AUC_{0-72 h} was 156.9%-187.4%, which was not within the standard interval of bioequivalence. The intestinal absorption of MRCE was significantly better than that of free metformin; MRCE improved the oral bioavailability of metformin and was not bioequivalent to metformin.