Erythromycin clinical observations

Based on observations in dogs and rabbits, clarithromycin is significantly less potent than azithromycin and erythromycin as an agonist for stimulation of smooth muscle contraction (32). A lower rate of gastrointestinal adverse events would therefore be expected with clarithromycin than with azithromycin (Table 2). Since most of these data were compiled from several studies, and since most have not been obtained by direct comparison of the various macrolides in single studies, the rates should be interpreted with caution. They most probably provide only an approximate indication of the rate of adverse events. Small differences in rates between individual macrolides will in most cases not be clinically useful indicators of the true risk for the occurrence of adverse events. 

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