Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania. The disease has many forms, ranging from localized and self-healing cutaneous leishmaniasis (CL) to the systemic visceral leishmaniasis (VL), which is fatal if not treated. There are more than 12 million people at risk of disease worldwide and an estimated 50 000 deaths per year due to VL. There are no vaccines and there are few drugs available. All the drugs have limitations, for example, resistance, long treatment courses, toxicity, methods of administration and high cost. In humans the Leishmania parasites survive and multiply inside macrophage cells, which in case of VL are found in the liver, spleen and bone marrow. For a drug to be effective it should ideally reach a concentration at the site of infection (it's pharmacokinetic property, PK) which can kill the parasite (it's pharmacodynamic property, PD) without being toxic to other parts of the body. The aim of a good dosing regimen is to deliver and keep effective drug levels at the site of infection to successfully kill all the parasites over several days. The aim of the chemists designing a new drug is to give it the properties that maximise its distribution to these sites of infection. The determination of the relationship between drug PKs and PDs is therefore important in both drug development and drug treatment. Currently we know very little about the PKs and PDs of any of the drugs used for leishmaniasis and nothing about drug action and drug concentration at the site of infection. The dosing regimens used in treatments today have not been optimised based upon this PK PD understanding, which could lead to improved efficacy, lower toxicity, and less chance of resistance; the same applies to the design of drug combinations. We aim to fill this knowledge gap by characterising the PK/PD relationships of established anti-leishmanial drugs and provision of predictive models that can be used in both drug development, by academic groups and the pharmaceutical industry, and in determining dose regimens and the best drug combinations. We will ensure that the successfully established methods and models are made available to the academic community and pharmaceutical and biotechnology companies with programmes in this field. We intend to make a contribution to the more cost-effective and efficient development of novel and much-needed therapeutic agents for this neglected tropical disease.