POLY(METHACRYLIC ACID) INDUCED LIPOSOME AGGREGATION FOR MEASURING DRUG ENTRAPMENT

This report characterizes a procedure for rapidly and accurately deter mining the entrapment of vincristine or other water-soluble drugs in p olyethylene glycol-derivatized liposomes. Rapid liposome aggregation w ith poly(methacrylic acid) and pelleting by mild centrifugation separa tes liposome-associated vincristine from unentrapped drug. After colle cting the supernatant fraction, the pellet is resuspended and solubili zed in isopropyl alcohol. Quantitative uv spectrophotometry determines vincristine mass in both fractions. The mean accuracy (recovery) is 1 00.6% over an entrapped drug range from 70 to 99%. Within and between day precision of the method has a relative standard deviation of 0.76% for a single measurement. (C) 1995 Academic Press, Inc.