Taxane analogue
milataxel have been shown to bound to
proteins/tissues irreversibly. Extraction of the aforementioned bound
drug and metabolite was proven to be difficult task. Nonetheless, an extraction method had to be developed to accurately determine
drug concentration in tissues over time. This method would enable Taxolog, Inc. (Fairfield, NJ, USA) to accurately map the fate of
drug in mice and it would also enable to better design
drug dosing scheme for its maximum efficiency. A productive extraction technique for
milataxel (MAC-321, TL-139) in nude mice with various xenograft human
tumors was developed by extracting analytes from
tumors using a novel extraction procedure and analyzing samples by LC-MS. This extraction technique entails disrupting tissue cells with
hexane followed by acidic
methanol (MeOH), with the aid of a tissuemizer and sonic cell disrupter. An average extractability of 75% was achieved as confirmed by the recovery of 14C labeled
milataxel, as compared to 4-48.5% extraction efficiency using
solvents and/or combination of
solvents such as
acetonitrile (
ACN),
ethanol,
ethyl acetate, MeOH/
acetic acid in water, and
chloroform/MeOH. This extraction technique allowed for quantitation of
milataxel and its major metabolite s-
lactate (M-10) from
tumors and brain tissue samples using HPLC coupled with electro-spray ionization mass spectrometry (HPLC-ESI-MS). Ratios of M-10 metabolite to
milataxel were determined to be approximately 3:1 and 2:1 in SKMES human lung
carcinoma tumors and A-375
melanoma tumors, respectively, and declined in concentration over 20 days. However, levels of
milataxel and M-10 were determined to be equal at 8h in HCT-15 human colon
carcinoma tumors with M-10 levels dropping sharply over a 10-day period.