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The present work is aimed to develop a simple, sensitive, robust and reliable HPLC method for the estimation of irinotecan in the physiological media in order to assess the permeability profile of irinotecan (by everted gut sac) in the presence of various P-gp modulators. Separation was achieved using, C18 column with mobile phase consisting of acetonitrile and 0.045µM sodium dihydrogen phosphate dihydrate buffer containing ion pair agent heptane sulphonic acid sodium salt (0.0054 µM), pH 3. The flow rate was maintained at 1 ml/min and analysis was performed at 254.9 nm using PDA detector. Calibration data showed an excellent linear relationship between peak-area vs drug concentration (r2, 0.9999). Linearity was found to be in the range of 0.060-10.0 µg/ml. Limits of detection (LOD) and quantification (LOQ) were found to ≈0.020µg/ml and ≈0.060 µg/ml, respectively. The developed method was found to be precise (RSD < 1.5%, for repeatability and <2.55 % for intermediate precision, acceptable ranges of precision), accurate (The recovered content of IRT in the presence of various P-gp modulators varied from 96.11-101.51, within acceptable range, 80-120%), specific and robust (% RSD<2). Developed method has been applied successfully for the evaluation of eleven P-gp modulators from diverse chemical class.

Key words: HPLC, Irinotecan, P-gp modulators, Everted Gut sac and Oral bioavailability enhancement

Irinotecan (CPT-11) is a topoisomerase I inhibitor, FDA approved drug for the treatment of colorectal and small cell lung cancer. It acts on DNA-topoisomerase-I, inhibits it and stabilizes the complexes formed during DNA replication resulting in cell death[1]. Irinotecan itself is a prodrug and converts into an active metabolite, 7-ethyl...

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...V detection was developed in the Tyrode’s solution, the commonly used physiological media for conducting the in vitro studies associated with intestinal tissues. However, various HPLC methods have been reported for determination of irinotecan, some of them coupled with expensive equipments such as LC-MS or fluorescence detectors[13-15]. Gradient programmed HPLC method coupled with UV-detector was also reported but with a drawback of long run time of 35 minutes [1]. Furthermore, HPLC-UV analytical methods with lower run time were also reported[3,16]. However, these methods were not validated for their accuracy/ recovery with wide range of excipients as per our review of literature. Hence, a suitable analytical method was developed. In addition, the developed method has been validated for its accuracy/ recovery in the presence of wide range of formulation excipients.