RESUMEN
INTRODUCTION: Cutaneous leishmaniasis (CL) is a serious health problem in some parts of the world, such as Iran. Since the use of pentavalent antimonial compounds such as meglumine antimoniate (Glucantime, MA) for the treatment of CL has side effects, naloxone as a new treatment in the footpad of Leishmania major (L. major)-infected BALB/c mice was investigated by evaluating the lesion size and the parasite burden. METHOD: The animals were infected with L. major (MRHO/IR/75/ER). 40 BALB/c mice were divided into 4 groups (10/group), and were treated as follows 39 days after L. major infection: Group 1 treated with intraperitoneal injections of MA (100 mg/kg, positive control group) daily for six weeks; Group 2 received a 100 µl injection of PBS (negative control group); Group 3 received subcutaneous (SC) injections of naloxone (10 mg/kg) daily for six weeks (Naloxone1), and Group 4 was SC injected with naloxone (10 mg/kg) weekly for six weeks (Naloxone2). The lesion size was measured using a digital caliper. RESULT: After the end of treatment, the lesion parasite burden was evaluated. As compared to the negative control group, the groups that received MA and naloxone (groups 1, 3, and 4) showed fewer parasites. Also, the naloxone-treated mice showed significantly smaller lesion sizes than the negative control group (pË0.05), but they did not differ significantly from the MA-treated mice. CONCLUSION: Taken together, the results suggest that naloxone might be a promising and alternative treatment for CL.