Effect of imidazolium-based ionic liquid on the antibacterial activity of an expired drug rifampicin

Abstract

The biggest concern of now is related to the expiry of drugs and their disposal. The utility of expired drug due to lost potency with the time has no clinical application and is associated with several significant risks. The application of expired drugs is neither notified nor enforced by any health policymaker nor by any country. This may be due to the lesser evidence showing the hazardous effect of an expired drug on human or animals. The expired drugs are being thrown without following any safety measures which results in developing bacterial resistance. Another, biggest reason for the expiry of a drug is related to the stability of the salt and liquid form of the drug which can be enhanced by several measures such as using Ionic liquid (ILs), making liquid formulation etc. The present study deals with the investigation of expired Rifampicin, RIF (E), against E. coli and S. aureus. Initially, the structural stability of expired and fresh Rifampicin was confirmed using 1H NMR and LCMS techniques. Further, the antimicrobial activity of expired Rifampicin was assessed in the absence and presence of imidazolium-based-ILs. From the biological activity results, the MIC of RIF (E) has decreased from 0.010 µM to 0.005 µM in presence of 10 µM [BMIM]BF4− against E. coli whereas, the MIC value against S. aureus remained unchanged. Likewise, the MIC of RIF (E) decreased from 0.010 µM to 0.002 µM in the presence of 0.5 µM [DMIM]BF4− against E. coli whereas, MIC against S. aureus was improved from 0.005 µM to 0.002 µM in presence of 0.1 µM [DMIM]BF4−. Additionally, the hemocompatibility study revealed the compatibility of composition with Human Serum Albumin. Further, the hemocompatibility of the composition was determined using fluorescence, absorption and circular dichroism (CD) spectroscopy. This might help in repurposing the expiry drug in other we may predict the increased life expectancy of the drug before its expiry.