The present invention provides low-residual-solvent containing excipients with
residual solvent less than <3000 ppm. Most of the excipients are required to first
be modified to become more water absorbing such as by attaching a water absorbing
radical, e.g., (-CH2COONa) to the carbinol groups (-CH2OH)
of the excipients to form a -CH2-O-CH2COONa linkage. The
linkage of the water-absorbing groups to e excipients improves the water absorbing
property of the excipients, which facilitates the replacing residual solvent with
water. The residual solvent can be extracted from the excipient by way of mixing
with a solvent/water solution containing (1) about 75-95% (v/v) isopropanol and
about 5-25% water (v/v); (2) about 65-95% acetone and about 5-35% water; and (3)
about 60-85% methanol and about 15-40% water.