<p>Chloramphenicol has been shown to retard the biotransformation of tolbutamide, phenytoin, and dicoumarol in man. Chloramphenicol should be used with caution if administered concomitantly with lincomycin, clindamycin, or erythromycin. In vitro experiments have demonstrated that binding sites for erythromycin, lincomycin, clindamycin and chloramphenicol overlap and competitive inhibition may occur. Rifampin therapy can reduce Chloramphenicol concentrations.</p>