An open label randomized clinical trial comparing the safety and effectiveness of one, two or three weekly pentamidine isethionate doses (seven milligrams per kilogram) in the treatment of cutaneous leishmaniasis in the Amazon Region

Background

American Cutaneous Leishmaniasis (ACL), a vector borne disease, is caused by various species of Leishmania and in the Amazonas, Leishmania guyanensis is predominant. The recommended drugs for treatment of cutaneous leishmaniasis (CL) in Brazil are pentavalent antimonials, pentamidine isethionate (PI) and amphotericin B. Pentamidine was initially used as metanolsulfonate or mesylate (Lomidine) at a dose of 4 mg/kg/daily, containing 2.3mg of base. This drug was withdrawn from the market in the eighties, and currently is available as PI. The PI dose required to achieve an equivalent dose of pentamidine base is 7 mg/kg, rather than the 4 mg/kg that is currently recommended in Brazil.

Objectives

The aim of this study was to evaluate the efficacy and safety of PI in a single dose, two or three doses of 7 mg/kg body weight, intramuscularly, with an interval of seven days between each dose.

Materials and methods

This study was conducted as a controlled, randomized, open–label clinical trial for a total number of 159 patients with CL. Individuals aged 16–64 years with one to six lesions of confirmed CL based on amastigotes visualization in direct examination of Giemsa stained of dermal scraping from the border of the lesion with no previous treatment for CL and no abnormal values for liver enzymes were eligible to participate in the study. Patients with history of diabetes, cardiac, renal, and hepatic disease as well as pregnant women were excluded. Cure was defined as complete healing in the diameters of the ulcers and lesions skin six months after the end of the treatment.

Results

From November 2013 to December 2015, 159 patients were screened and allocated in three groups for treatment with PI: i) 53 patients were treated with a single dose intramuscularly injection of 7 mg/kg body weight; ii) 53 received two doses of 7 mg/kg within an interval of seven days; and iii) 53 were treated with three doses of 7mg/kg with an interval of seven days between each dose. In 120 patients, L. guyanensis was identified. A cure rate of 45%, 81.1% and 96.2% were observed in the first, second and third group, respectively. The cure in the three PI dose group was higher compared to the single-dose (p<0.0001) and two-dose groups (p = 0.03). No serious adverse events occurred.

Conclusion

The present study shows that PI is a safe drug and its efficacy varied with the number of doses. The administration of PI in patients with ACL, predominantly caused by L. guyanensis, was mostly efficient in three or two doses of 7 mg/kg.

Trial registration

ClinicalTrials.gov NCT02919605

Ninety percent of all cases of CL are concentrated in five countries, including Brazil. Brazil is among the most endemic countries in the Americas. According to the Brazilian Ministry of Health, 30,000 new cases are diagnosed every year and the prevalent species are L. braziliensis and L. guyanensis. In the region of Manaus (Western Amazon), L. guyanensis is responsible for 95% of the cases of CL. The recommended drugs for treatment of CL in Brazil are pentavalent antimonials, PI and amphotericin B (AmB). Pentavalent antimonial is the first-line treatment in Brazil, and AmB is recommended as second-line. The recommended dose for the treatment of CL is 10–20 mg/kg/day of meglumine antimoniate for a period of 20 days. Its efficacy varies from 26.3% to 81.6%. For treatment with AmB, the patient must come to the hospital and be monitored for renal function for several hours. We report a phase II pilot study comprising 159 patients with CL due to L. guyanensis treated with PI. The patients were randomly divided in three groups: 53 received a single intramuscular injection of 7mg/kg PI salt; 53 received a regimen of two intramuscular injections of 7 mg/kg within a seven-day interval; and 53 were treated with three intramuscular injections of 7 mg/kg with a seven-day interval between each dose. All patients live in the region of Manaus and were monitored at Tropical Medicine Foundation of Amazonas. Patients underwent a dermatological and laboratorial examination at the start of the study and at weeks 1 and 4. PI was well tolerated and no severe adverse effects were detected. After a 6-month follow-up, we observed 81.% and 96.2% effectiveness for the cure rates in the groups receiving two and three intramuscular injections of 7 mg/kg PI in ACL patients at one-week intervals between doses, respectively. Only 45.3% of the patients treated with a single dose of the medication were considered to be cured. The use of PI in the aforementioned doses is the best option to treat ACL in this region given the long distance, the difficulty in accessing health centers, and the L. (V.) guyanensis predominance in the Brazilian Amazon. We recommend either two or three weekly doses of PI at 7 mg/kg for the treatment of ACL patients in the region.

The change of behaviour of two strains of Leishmania after cultivation in a defined medium

Attempts have been made to characterize two strains of Leishmania that became infective to golden hamsters only after they had been maintained for several years in a chemically defined culture medium. Observations were made on the growth rates of promastigotes in vitro, course of infection in hamsters, morphology of amastigotes, and electrophoretic mobility patterns of eight isoenzymes. Information was obtained about the buoyant densities of n-DNA and k-DNA, and one strain was tested against monoclonal antibodies. The identity of both strains remains obscure.