Effects of swimming on the pharmacokinetics and glucose tolerance of metformin in insulin-resistant rats

The purpose of the study was to investigate the effects of swimming on the pharmacokinetic and insulin sensitivity of metformin in insulin resistant rats. Rats with fructose-induced insulin resistance were assigned into four groups: control group (C, n=8), metformin group (M, n=8), swimming group (S, n=8) and metformin with swimming group (MS, n=8). After 12h of fasting, the S and MS group swam for 45 min, while the M and C groups were placed in 4 cm deep water for the same time period. The first blood samples were withdrawn from the tail 60 min after the four groups had left the water. An oral glucose loading was performed in an groups and metformin was administered to the M and MS groups after the first blood sample. Blood samples were collected at 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 10 and 12 h. The results showed that the MS group increased the time to the maximum concentration, the time to half-life concentration and enhanced insulin sensitivity. This study suggests that swinuning before administration of metformin significantly improved insulin sensitivity and the rate of metformin absorption. Copyright © 2008 John Wiley & Sons, Ltd.