DIRECT PHARMACEUTICAL ANALYSIS OF BISPHOSPHONATES BY CAPILLARY ELECTROPHORESIS

Bisphosphonate compounds have been studied as a class of potential dru gs for the treatment of various bone diseases. However, the analyses o f these compounds are problematic because most of them do not contain strong chromophores. Based on the unique structures of these compounds , we have employed a capillary electrophoresis (CE) technique for the characterization of these compounds in pharmaceutical dosage formulati ons. In this study, two CE methods were developed for the determinatio n of a bisphosphonate compound, 2-thioethane-1,1-bisphosphonic acid. T he first method involved the use of an uncoated column, a phosphate bu ffer, and hydrostatic injection with direct UV absorbance detection. T he method showed excellent resolution and precision with a reasonable detection limit of 30 mu g/ml. Sensitivity was further improved using a glycerol-coated column, together with a phosphate buffer of higher c oncentration and electrokinetic injection under sample stacking condit ions. This modified method revealed a significant improvement in sensi tivity with a detection limit of about 50 ng/ml. Both methods demonstr ated high simplicity and excellent reproducibility and were successful ly applied to the quantitative analyses of pharmaceutical dosing solut ions. (C) 1998 Elsevier Science B.V.