Clarithromycin is a semi-synthetic derivative of erythromycin. Clarithromycin differs from erythromycin in itís methyl substitution at the number six position of the macrolide ring. Clarithromycin also has an active metabolite, 14-hydroxy clarithromycin which has been reported to be "synergistic" with the parent compound. Click here for the structure of clarithromycin and its active metabolite.
Clarithromycin has "proven clinical efficacy" in the treatment of pediatric AOM and sinusitis. Like azithromycin, clarithromycin can be used safely down to age six months and is able to achieve tissue concentrations in excess of serum concentrations. Clarithromycin is probably more effective against S. pneumoniae than is azithromycin.
Daily dosage for the treatment of AOM is 15 mg/kg/day in two divided doses for a total of 10 days. Significantly, clarithromycin should not be refrigerated. Administration with food produces little change in peak serum concentrations. Like azithromycin, adverse reactions with clarithromycin are rare and generally consist of GI complaints (< 6%). Click here for specifics on prescribing clarithromycin.