Chirality Status Of Registered Medicines In Tanzania: A Retrospective Cross-Sectional Study

Abstract Background Medicines with a stereogenic center (asymmetric carbon) mainly presents as racemates with a mixture of equal amounts of enantiomers. One enantiomer may be active while the other inactive, alternatively one may produce side-effects and even toxicity. Worldwide there is no mandatory regulatory requirement to enforce the development of new chiral medicines as exclusively pure active single enantiomers. This has contributed to the existence of both single enantiomers and racemates on the market. Moreover, literature shows the tendency of regulatory approval of medicines towards the development of pure single enantiomers 60%, only 5–10% racemates and 30–35% as achiral. This status has not been established particularly in African countries including Tanzania. Therefore, we aimed to establish the chirality status of registered medicines in Tanzania. Methodology: A retrospective cross-sectional study was conducted by reviewing all human medicines registered in Tanzania for the past 15 years from 2003 to 2018. Data were extracted from TMDA-IMIS database to Microsoft excel for analysis. Medicines were assessed to determine if they were chiral (racemates or single enantiomers) or achiral. Results A total of 3,573 human medicines had valid registration. Most of these medicines 2,150 (60%) are chiral and 1,423 (40%) are achiral. Out of the chiral medicines, 1,591 (74%) and 559 (26%) were racemates and single enantiomers, respectively. The percentage of chiral medicines for anti-infective (35%) was significantly higher (p < 0.0001) than other pharmacological groups. A high proportion of chiral medicines within pharmacological groups were observed in systemic hormonal preparations (excluding reproductive hormones and insulin) 97.3% (36/37) and anti-infectives 80% (753/941). Conclusion The study revealed the existence of both chiral and achiral registered human medicines with chiral medicines predominating. The proportion of racemates within chiral medicines was significantly higher than that of single enantiomer medicines. The use of these racemates may cause harm to the public and may also contribute to antimicrobial resistance due to the potential existence of inactive and toxic enantiomers. In order to protect public health, regulatory bodies need to strengthen the control of chiral medicines by including an analysis of enantiomeric impurity.