In Vitro Drug Interactions Study of Lisinopril with Metformin

The objective of this study was to investigate the in vitro interactions of lisinopril with metformin using the principle of the dissolution test. The study was conducted using the USP apparatus II paddle method with the temperature set at 37¿C body temperature. The media used were buffer pH 1.2, 4.5, and 6.8 to simulate gastrointestinal tract pH. Lisinopril tablets (10 mg strength) were run in the presence of 500 mg metformin tablets and the degree of interaction was established after analyzing the dissolution samples with High-Performance Liquid Chromatography coupled with a ultra-violet detector. The results indicated a statistically significant difference in the effect of lisinopril on the dissolution profile of metformin at pH 1.2, 4.5, and 6.8, with a decrease in the percentage of metformin, released (p = 0.0052; p = 0.0037; and p = 0.0155, respectively). The effect of metformin on the dissolution profile of lisinopril was statistically significant at pH 1.2 and 6.8 with an increase in the percentage of lisinopril released (p = 0.0062; p =0.0036, respectively). However, there was no statistically significant difference at pH 4.5 (p = 0.7174).