Metronidazole for Amoebiasis: A tale of more than half a century

Metronidazole has many unique properties such as possessing antibacterial as well as anti-protozoal activity, very minimal resistance rate, acceptable safety profile and market longevity. Metronidazole has remained as the recommended drug in the treatment of any form of amoebiasis caused by Entamoeba histolytica since its inception almost half a c entury ago. Anaphylaxis which limits the use of many antibacterial agents is hardly reported with metronidazole accounting for its favourable safety profile. Owing to its low-cost, it is considered affordable and economically accessible in developing countries which are mainly affected by amoebiasis. Its pharmacokinetic properties considered are its asset as well as drawback. For example, good bioavailability and good tissue penetration allows metronidazole to be used as oral dosage form in many indications and responsible for its efficacy in many extra-intestinal amoebiasis. However, inhibition of hepatic drug metabolizing enzymes is responsible for some significant drug interactions, and disulfiram like effect with alcohol. Unlike many other antimicrobial agents which were discovered much later, metronidazole has withstood the problem of antimicrobial resistance. Even some longer acting agents have been developed in the recent past, metronidazole remains the drug of first choice for amoebiasis documenting very high cure rate with minimal need for other treatment modalities.