Raman spectroscopy provides accurate and cost-effective quality control of pharmaceuticals, which is essential for maintaining the confidence of dispensing physicians and patients’ adherence to therapeutic regimens. For drug salts that contain a counter-ion, the active pharmaceutical ingredient and counter-ion combination is optimized for the intended therapeutic effect. Drug products with alternative counter-ions are regulated independently because there is potential for a counterfeit or adulterated medication to differ only by the counter-ion. This study demonstrates that backscattering and transmission Raman spectroscopy can identify these potentially adulterated products. Four case studies using common medications that have multiple counter-ion forms were selected for identification comparison using Raman spectroscopy and HPLC-UV. One case study shows that an adulterated product with the incorrect counter-ion label entered the pharmacy supply chain in the United States and was easily detected by Raman spectroscopy. For all study medications, the United States Pharmacopeia HPLC-UV method could not identify inorganic counter-ions. Importantly, a single unique method was developed for each Raman technique that was then applied to all medications, saving considerable time in development, processing of the medications, and cost compared to HPLC-UV. This study promotes Raman spectroscopy for correct counter-ion surveillance in finished drug products, which should be of interest to public and private regulatory agencies and quality control activities.

Raman spectroscopy for pharmaceutical counter-ion identification

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.