Treatment of cutaneous leishmaniasis with nitric-oxide donor

Abstract

Nitric oxide (NO) released by activated murine macrophages exerts a powerful cytostatic and cytotoxic effect against a variety of pathogens, including Leishmania major. We have investigated whether S-nitroso-N-acetylpenicillamine (SNAP), a compound that generates NO, could be a therapeutic agent in human cutaneous leishmaniasis. 16 Ecuadorean patients (4–37 years old) were selected by the following inclusion criteria: the presence of only one skin ulcer (14–26 mm largest diameter), positive staining for leishmania amastigotes in lesion exudate, and no drug treatment. To confirm the diagnosis, a tissue sample was obtained from the centre of the ulcer with a 4 mm diameter disposable biopsy punch. The sample was cultured in a Novy-MacNeal-Nicolle medium for 10 days, after which time the presence of leishmania was determined. The appearance of a single 70 bp amplification product following the polymerase chain reaction identified the leishmaniasis as the braziliensis variety in all cases. A cream of SNAP (donated by Glaxo Wellcome) with a final concentration of 200 μmol/L was prepared using cetyl alcohol (1hexadecanol), quarternary ammonium, and distilled water. Release of NO by the cream was verified by testing an aqueous extract for its vasodilator and antiaggregatory actions. The aqueous extract was active for 4 h after dissolving the cream; however, the undiluted cream did not lose activity over 30 days. The SNAP cream was administered topically to the lesion every 4 h (except during sleep) for a total of 10 days. The progression of the ulcer was assessed visually by the same investigator (CR) during treatment. The protocol for the study was approved by the ethics committee of the Instituto de Investigaciones para el Desarrollo de la Salud (IIDES), Ministerio de Salud Publica del Ecuador. After 5 days, improvement of the ulcer and the presence of granulation were evident in all patients and after 10 days the ulcer evolved into granulation tissue. By 30 days all lesions were healed and new skin could be observed. There was no improvement in five patients who received vehicle alone. Side-effects were not observed, apart from a transient warm sensation on the lesion immediately after application of the cream. The clinical improvement was confirmed by the absence of leishmania in cultures of a second biopsy RESEARCH LETTERS