Improved drying method for removal of residual solvents from paclitaxel by pre-treatment with ethanol and water

In this study, a drying method was developed for the effective removal of the residual solvents, methylene chloride and methanol, in purified paclitaxel. When the sample purified by silica-HPLC was concentrated using a rotary evaporator, the residual methanol level easily met the ICH-specified value (3000 ppm), but methylene chloride did not meet the ICH-specified value (600 ppm). However, residual methylene chloride was easily and conveniently removed below the ICH-specified value by rotary evaporation (∼1 h) alone after pre-treatment of a sample (methylene chloride: 17,600 ppm) with 95% ethanol. In addition, residual ethanol (>14,300 ppm) met the ICH-specified value (5000 ppm) after simple rotary evaporation (∼1 h) alone with pre-treatment with water, and residual water also met the specified value (<4%) for active pharmaceutical ingredients.