**4. Conclusion and future trends**

In comparison with economically more attractive diseases like cancer, cardio-vascular problems and allergies, commercial interest in developing new antiparasitics is still rather low. Low income of most of the people affected by leishmaniasis, as it is the case for other tropical diseases, discourages big pharmaceutical companies from investing in developing new therapies. Therefore there is an urgent need to investigate into new drugs with low cost of production but also with high efficacy and selectivity.

Research on metal-based compounds to treat leishmaniasis has resurged in the last years and significant progress has been made. The possibility to finely tune their reactivity through a change of the metal ion and appropiate choice of the ligand/s makes of metal compounds promising alternatives to fight this disease in a cost-effective way.

Optimization of currently available metal-based drugs such as antimonials through use of nanovehicles and attachment of targeting moieties may be an interesting option to overcome antimonials resistance problems and maybe the quickest way to produce effective results. Therapeutic effects might be enhanced by using e.g. metal nanoparticles as delivery carriers, which depending on the metal, might be able to produce high amounts of reactive oxygen species and induce oxidative stress to the parasites.

On the other hand, significant advances in parasite genoma sequences and identification of targets in the last years along with an increasing understanding of metals interactions with a wide range of biomolecules, will contribute to development of highly efficient target-specific metal-based drugs in the future while avoiding recurring to time-consuming drug screening methodologies.

Meanwhile some authors have pointed at the metal-drug synergism approach as a very useful alternative for drug design at the moment.
