Medycyna Wet. 66 (7), 453-458, 2010
Gajda A., Posyniak A.
Pharmacological properties of azalides - improved macrolides
In this paper the pharmacological properties of azalides, an improved group of macrolide antibiotics, have been reviewed. Worldwide interest in macrolide antibiotics has led to the development of several semi-synthetic derivatives of 14-membered erythromycin, such as 15-membered azithromycin and tulathromycin, with an additional nitrogen atom in the lacton ring. The newer macrolides, called azalides, have broader antibacterial activity against Gram-positive and Gram-negative pathogens as well as atypical pathogens of the respiratory system. They are characterized by better pharmacokinetic parameters, reduced adverse reactions and an improved drug-interaction profile compared with erythromycin. The application of these groups of antibiotics has some advantages over erythromycin, including longer half-lives and higher tissue concentrations, especially at the site of infection, which makes it possible to administer them once a day in the treatment of respiratory tract infections, in contrast to more frequent dosage required for erythromycin. Azalides are more acid-stable and therefore demonstrate greater oral bioavailability. In addition, these antibiotics have immunomodulatory and anti-inflammatory properties, which can be useful in the treatment of chronic disorders. The pharmacokinetic/pharmacodynamic relations, which are important in predicting clinical efficacy of antibiotics, are also reviewed. To ensure food safety, the European Commission had set Maximum Residue Limits (MRLs) for erythromycin, as well as for tulathromycin. However, azythromycin has not been certified for use in food producing animals, and therefore no MRLs have been established for this azalide.
Keywords: macrolides, azalides, pharmacokinetics, pharmacodynamics, structure, activity, residues