Optical crystallographic characteristics of some USP drugs.

Optical crystallographic data were determined on a variety of newer USP drugs for which data had not been previously obtained. The ingredients in an unknown sample can be identified by polarized light microscopy by mounting small amounts of the material in successive specific refractive index liquids and determining refractive indices, optic sign, type of extinction, estimated 2V angle, and other optical characteristics for each ingredient present. This information can then be compared with the data listed on known drugs and excipients and all of the ingredients can be identified. To aid in the identification of unknown drugs, optical crystallographic data obtained on 52 of the newer USP drugs are presented.