Development of a high-performance liquid chromatographic-mass spectrometric assay for the specific and sensitive quantification of Ro 64-0802, an anti-influenza drug, and its pro-drug, oseltamivir, in human and animal plasmaand urine

Oseltamivir phosphate (Ro 64-0796/002) is a pro-drug of the anti-influenza neuraminidase inhibitor, Ro 64-0802, and as Tamiflu(TM), has been developed for the treatment of both A and B strains of the disease. This paper descr ibes an HPLC-MS-MS assay for both compounds in plasma and urine which fulfi ls all of the criteria for a good analytical method. It is sensitive with l imits of quantification of 1 and 10 ng/ml for the pro-drug and active neura minidase inhibitor, respectively. It is both accurate and precise with typi cal coefficients of variation from some 5000 quality control samples of app roximately +/-3 and +/-6%, respectively. Extensive stability studies have d emonstrated the absence of significant problems associated with the decompo sition of either compound, although ex vivo hydrolysis of Ro 64-0796 to Ro 64-0802 in rodent plasma has to be prevented by the use of the esterase inh ibitor, dichlorvos. (C) 2000 Elsevier Science B.V. All rights reserved.