Pioglitazone.

Pioglitazone is a thiazolidinedione antidiabetic with actions similar to those of rosiglitazone. It is used in the management of type 2 diabetes mellitus and is prepared by reducing 5-[4-[2-(5-ethyl-2-pyridyl)ethoxy]benzilidene]-2,4-thiazolidinedione with sodium borohydride in the presence of a cobalt ion and dimethyl glyoxime. Ultraviolet spectroscopy shows maximum absorption at 270nm. Infrared spectroscopy shows principal peaks at wave numbers 3082, 2964, 1736, 1690, 1472, 1331, 1254, 1040, 841, 728cm(-1) (KBr disk). The determination method by high-performance liquid chromatography was linear over the range of 25-1500ng/mL of pioglitazone in plasma (r(2)>0.999). The within- and between-day precision values were in the range of 2.4-6.8%. The limit of quantitation of the method was 25ng/mL. It is well absorbed with a mean absolute bioavailability of 83% and reaching maximum concentrations in around 1.5h. It is metabolized by the hepatic cytochrome P450 enzyme system. Following oral administration, approximately 15-30% of the pioglitazone dose is recovered in the urine. Renal elimination of pioglitazone is negligible, and the drug is excreted primarily as metabolites and their conjugates. It is presumed that most of the oral dose is excreted into the bile either unchanged or as metabolites and eliminated in the feces.