Update on azithromycin and cardiac side effects

MechanisM of action of azithroMycin Azithromycin is a macrolide antibiotic and the sole member of the azalide subclass. Derived from erythromycin, it has an aza-methyl substitution (insertion of a nitrogen atom) in the macrolide ring. This addition increases the stability of its structure but does not change the mechanism of action(Figure 1). The addition of the second amine group resulted in important advantages over erythromycin, including greater tissue penetration and an extended half-life. 1 Azithromycin binds to the 50S ribosome subunit and blocks protein synthesis by inhibiting the transpeptidation/ translocation step. This prevents mRNA translation and ultimately inhibits bacterial growth. Macrolides typically have bacteriostatic activity but can be bactericidal at high enough concentrations and with very susceptible organisms.