In vivo investigation of antibacterial ointments

The clinically used topical antibiotic ointments, gentamicin 0.1%, oxytetracycline 3% w/polymyxin 0.1% and chloramphenicol 2% and an experimental preparation, 10-undecen-1-yl thiopseudourea iodide (AHR-1911) were studied for anti-infective action applied externally on the skin of mice inoculated subcutaneously with S. aureus and E. coli. In both infections statistically significant difference was encountered between curative and "clinical" healing rate in the case of the less effective preparations and/or dosages. The method appears suitable to establish and to compare the in vivo activity of ointments. This is not directly related to that of the aqueous drug solutions. AHR-1911, a powerful inhibitor of nucleic acid and protein synthesis, showed a bimodal action, with maximal effectiveness at 0.12-0.25% concentration, due presumably to the anti-inflammatory effect of higher concentrations. Direct evidence for the absorption of the drug from the application site was obtained using 14C labeled AHR-1911.