Advanced Dental Admission Test (ADAT)

What is the mechanism of action for Metronidazole?

1. Inhibition of ribosomal protein synthesis

2. Inhibition of nucleic acid synthesis

3. Blocking cell wall synthesis

4. Inhibition of folic acid synthesis

The correct answer is: Inhibition of nucleic acid synthesis

Metronidazole acts primarily through the inhibition of nucleic acid synthesis. This mechanism is crucial for its effectiveness against anaerobic bacteria and certain protozoa. The drug is reduced within these organisms to reactive intermediates that then interact with DNA, leading to the formation of free radicals. These free radicals disrupt the DNA's helical structure, inhibiting the synthesis and repair processes of nucleic acids. As a result, bacterial growth is effectively halted, and this is what makes Metronidazole a valuable agent in the treatment of various infections. Other mechanisms like inhibition of ribosomal protein synthesis, blocking cell wall synthesis, and inhibition of folic acid synthesis do not apply to Metronidazole as they correspond to the actions of different classes of antibiotics. Understanding this specific action helps to clarify why Metronidazole is particularly effective against anaerobic pathogens and certain parasites.