| Metformin hydrochloride (MH) is an oral antihyperglycaemic agent widely used in the treatment of non-insulin-dependent diabetes mellitus (type-2 diabetes). The elimination half-life of MH is about 2 hours. It reduces blood glucose levels, predominantly by improving hepatic and peripheral tissues sensitivity to insulin without affecting the secretion of this hormone. It also appears to have potentially beneficial effects on serum lipid level and fibrinolytic activity. The aim of this work was designed to develop a kind of MH sustained-release pellets which would reduce dosing frequency, narrow the fluctuation of blood concentration and be more convenient for patients to use.Ultraviolet spetrophotometry method was developed for assaying the content in the preparation and drug release from MH sustained-release pellets. MH is freely soluble in water or various physiological pH fluids and the apparent partition coefficient in n-octanol/water system is 0.5818.To investigate the absorption characters of MH in intestine, the absorption kinetics was studied by utilizing the rat intestinal absorption recirculating method in situ. After perfusing for 6h, the permeability rate constant (h-1) of duodenum, jejunum and ileum per 10cm were 0.0657 h-1, 0.0381 h-1,0.0157 h-1, respectively. The absorption in colon was almost not detected. Concentration and pH value had no effect on the absorption kinetics. The absorption of MH was a first-order process with the passive diffusion mechanism.MH pellets were prepared in a centrifugal granulator with MCC as dilute...
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