DETERMINATION OF GI147211 IN HUMAN BLOOD BY HPLC WITH FLUORESCENCE DETECTION

GI147211 (GG211) is a camptothecin analogue, which exhibits antileukem ic and antitumor activity by blocking DNA synthesis. The drug stabilit y considerations' and specimen handling were important aspects in meth od development and validation. This method involves collection of bloo d at the clinical site, immediate freezing, and storage at -70 degrees C. The lactone form is extracted from blood at physiological pH with a mixture of n-butyl chloride and acetonitrile (4:1); the carboxylate is not extracted under these conditions. After evaporation the extract is injected into an HPLC system with a fluorescence detector set at 3 78/420 nm. The internal standard used is 6,7-dimethoxy-4-methylcoumari n. The main advantages of the procedure are the separation of lactone and carboxylate by means of extraction, simplified specimen collection at clinical sites and the ability to inject almost all of the extract ed material (extraction recovery, 60%) into an HPLC system. The method has been validated over the range 0.15-100 ng ml(-1) with sufficient precision and accuracy (coefficient of variation below 10%) to support pharmacokinetic studies. Under the conditions of this procedure, the drug is stable in human blood at -70 degrees C for at least 93 days, a s well as through two additional freeze-thaw cycles.