Comparison of Italic cytoxicity of generic paclitaxel and irinotecan formulations with their reference formulations on seven human intrahepatic cholangiocarcinoma cell lines

Abstract

Background: Several chemotherapies have now been introduced for the treatment of cholangiocarcinoma (CCA).  Although it has previously been reported that two new chemotherapeutic agents, paclitaxel and irinotecan, showed strong cytotoxic effect to human CCA cell lines the treatment cost currently using reference formulations of these two drugs are very expensive.  To date, the generic drugs for both paclitaxel and irinotecan are now commercially available in Thailand with relatively low price compared to reference formulations.  However, the study demonstrating the efficacy of the innovator and generic formulation of these two agents has never been reported.

Objective: To determine and compare the cytotoxic activity of generic paclitaxel and irinotecan formulations with the reference formulations on seven human intrahepatic CCA cell lines.

Design: In vitro study

Setting: Faculty of Medicine, Khon Kaen University

Material and Method: Cytotoxic activitiy of chemotherapeutic agent on CCA cellines was determined by sulforhodamine B (SRB) assay.  The IC₅₀ value expressed as the concentration of drug that caused a 50% growth inhibition comparing with no drug treated control.  The cytotoxic activity of the generic formulation was compared to the reference formulation using Student’s unpaired t-test.

Results: Paclitaxel exhibited strong potency towards most CCA cell lines with IC₅₀ values ranging from 0.001-1.40 M whereas irinotecan showed IC₅₀ values ranging varied from 0.02 to 69 M. KKU-M055 was the most sensitive cell line to paclitaxel and KKU-OCA17 showed the highest sensitivity to irinotecan whereas KKU-M156 was the least sensitive cell line to both drugs. IC₅₀ values of the generic product (Intaxel^Ò, Dabur, India) and reference product (Taxol^Ò, Bristol-Myers Squibb, USA) formulations were not significantly different (P > 0.05).  Similary, the cytotoxicity of the generic formulation of irinotecan (Irinotel^Ò, Dabur, India) was not statistically significant different from the reference formulation (Campto^Ò, Aventis Pharma, UK).

Conclusion: The cytotoxic activity of paclitaxel towards six CCA cell lines was more potent than irinotecan except for KKU-OCA17.  No different in the IC50 values of the generic and reference formulations of paclitaxel and irinotecan agents seven CCA lines suggest that the in vitro efficacy of generic and reference formulations of these two drugs are very similar.

Keywords: Cytotoxic activity, paclitaxel, irinotecan, cholangiocarcinoma, generic formulation