Study on influence of physicochemical property of an active pharmaceutical ingredient against THz spectrum: Example of CNS stimulant

Caffeine and sodium benzoate (CSB), the central nervous system (CNS) stimulant, which is sometimes illegally used with amphetamines to obtain sexual arousal was used in this study. According to comparison of terahertz spectra obtained from three CSB distributed as Japanese Pharmacopoeia (JP) active pharmaceutical ingredients (APIs), difference of one terahertz spectrum of three manufacturers was observed. This observation seems to be due to slightly different crystal structure of CSBs. The characteristic terahertz spectrum based on the manufacturing process can be utilized as fingerprint information to detect fake or substandard API, or mixing of counterfeit drugs.