Comparative study of peripheral neurotoxicity after injection of two different paclitaxel formulations in rats

Paclitaxel Inj. [NK] (test; paclitaxel, CAS 33069-62-4) is a generic version of the drug from the originator (reference). Both drugs contain the same active ingredient and showed identical pharmacokinetics in patients in the previous study; however, these two drugs may have different safety profiles because they contain different inactive ingredients. Thus, in this study, peripheral neurotoxicity, one of the dose-limiting toxicities of the reference, was compared between the test and the reference in rats electrophysiologically and histopathologically. In a nerve conduction study, the amplitude of the caudal sensory nerve action potential decreased significantly after either the test or the reference administration, compared with the amplitude after saline administration, but no significant differences were observed between the two drugs. Histopathologically, apparent degeneration of the myelinated fibers in the sciatic and the sural nerves was seen after either the test or the reference injection, compared with after saline injection, but no apparent differences were observed between the two formulations. These results suggest that no significant difference in peripheral neurotoxicity exists between the test and the reference in rats.