Transmission Raman Spectroscopy (TRS) for Accurate Authentication of API in Coated Hydroxychloroquine (HCQ) Tablets

ABSTRACT Hydroxychloroquine (HCQ) is widely used as an antimalarial, anti‐inflammatory, and immunomodulatory drug. However, adulteration of the API in HCQ tablets not only adversely affects the efficacy of this common drug but also raises the risk to the recipient significantly, which many a times can lead to life threatening conditions. Hence, authentication of the API of HCQ tablets is an unmet need globally, requiring urgent attention. The current methods of API authentication in a coated tablet are chemical intensive, costly, and time‐consuming and are not specific to the molecules forming the API. Herein, we report, the development and use of a transmission Raman spectroscopy (TRS) system for a more accurate but nonintrusive way of authentication of HCQ tablets in presence of the coating which otherwise is not possible using the conventional chemical methods and the existing configurations of Raman spectroscopy. The outcome of the study conducted on five different commercial brands of HCQ is that while the backscattered Raman signals, because of the large interference arising out of the coating itself, deviated significantly (particularly at ~400, 518, and 642 cm −1 ) from the Raman spectrum of pure API, the interference was almost zero in case of the signals obtained using TRS, and a greater extent of spectral matching ( R 2 > 0.97) could be noted. The higher sensitivity of TRS towards the inner contents (i.e., API) of the tablets and insignificant susceptibility to the coating on the tablet surface reveals its true potential for an accurate authentication of the API.