The purpose of this study is to determine the pharmacokinetics of miltefosine in children and adults with cutaneous leishmaniasis in plasma and intracellularly, and its relation with the parasitologic response. The results will provide pharmacologic bases to optimize the use of miltefosine for the treatment of cutaneous leishmaniasis, and will provide the knowledge base to assess the impact of pharmacokinetic behavior in children and adults on the emergence of drug resistance.

An open-label phase IV clinical trial of miltefosine, designed to evaluate intracellular and plasma drug pharmacokinetics in children and adults using a population pharmacokinetics design. Two study groups have been defined: 1) children 2-12 years of age (n=30) and 2) adults 18-60 years of age (n=30) with confirmed parasitological diagnosis of cutaneous leishmaniasis. The participants will receive supervised standard treatment with miltefosine: 1.8 - 2.5 mg/Kg of weight for 28 days.

Miltefosine concentration will be determined in plasma and Peripheral Blood Mononuclear Cell (PBMCs), from 3 or 10ml peripheral blood samples in children and adults respectively. Sampling will be conducted pre-dosing at days 0,1,15 and 29 during treatment, and at months 1, 2, 3 and 6 post-treatment.

A population pharmacokinetics analysis will be performed using a non-linear model of mixed effects with the software Nonlinear Mixed-effects Model (NONMEM), R and Piranha. Parasite burden will be determined by 7SLRNA Quantitative Polymerase Chain Reaction (qPCR) of Leishmania from swab samples of lesions and extralesional tissues before and at the end of treatment. The relationship between pharmacokinetics and parasite persistence/burden will be determined by correlation analysis and pharmacodynamic modeling.

Inclusion Criteria:

• Age: 2-12 years of age, or 18-60 years of age
• Weight greater than 10 kg
• Parasitologic confirmation of cutaneous leishmaniasis
• Normal hepatic and kidney function

Exclusion Criteria:

• Pregnant or lactating women, and women who are planning to conceive during the study or that reject the use of birth control methods.
• Use of drugs with antileishmanial potential during the previous 6 months, including pentavalent antimonials, amphotericin B, miltefosine, and pentamidine
• Mucocutaneous or visceral leishmaniasis
• For female children, menses or other evidence of reproductive maturity