Long chain lipid based tamoxifen NLC. Part II: Pharmacokinetic, biodistribution and in vitro anticancer efficacy studies

Long chain lipid (LCL) based tamoxifen loaded nanostructured lipid carriers (Tmx-NLCs) meant to target intestinal lymphatic systems (ILSs) was developed and characterized previously. The aim of the present work was to evaluate in vitro efficacy of developed Tmx-NLC against breast cancer cell lines and to confirm the hypothesis of targeting ILS after single dose oral administration. In vitro anticancer activity of Tmx-NLC was assessed in human estrogen receptor expressing breast cancer cell lines viz. MCF-7 and ZR-75-1. The study revealed relatively improved activity for Tmx-NLC compared to free Tmx against MCF-7 cells. However, the activity was compromised against ZR-75-1 cells which could be attributed to its up regulation of MUC1 gene. Confocal and flow cytometric analysis revealed remarkable intracellular uptake of Tmx-NLC and its localization in nuclear and perinuclear region of cells. Tmx-NLC exhibited distinctly different pharmacokinetic profile compared to Tamoxifen suspension (Tmx-susp) and exhibited an increment in the bioavailability by 2.71-fold and prolonged the T-1/2 by 7.10-fold. Moreover, detectable drug concentration in mesenteric lymph nodes justifies our hypothesis of targeting ILS and explains the major uptake of Tmx to occur via lymphatic system. (c) 2013 Elsevier B.V. All rights reserved.