Azithromycin differs from other macrolides in its azalide structure. The azalide structure has a methylated nitrogen atom in the number 9a position on the macrolide lactone ring. Click here for the structure of azithromycin.
Azithromycin is sequestered in leukocytes and therefore available at the site of infection in higher concentrations than serum levels. Click here for graphic of serum vs. WBC concentrations. Although dosed for five days, azithromycin maintains therapeutic serum levels six days after discontinuing the drug.
Azithromycin has been released for use in pediatric respiratory illnesses at a dosage of 10 mg/kg as a single dose on day one, followed by 5 mg/kg daily for four days (given as a single daily dose). The maximum pediatric daily dose is 500 mg on day one and 250 mg on days two through five. Azithromycin can be safely given down to six months of age. Studies have shown azithromycin to be as effective as amoxicillin/clavulanate in treating acute otitis media.
Azithromycin does not have to be refrigerated. The package insert does recommend giving this medication one hour before meals or two hours after meals. However, such precautions do not seem applicable when using the pediatric suspension. Click here for specifics on prescribing azithromycin. For more information on Azithromycin see Pediatric Infectious Disease Journal, supplement to the April 1995 issue.