Adverse effects of chemotherapeutic agents used in tropical medicine.

Traditionally, many of the chemotherapeutic agents used in tropical medicine have possessed limited efficacy and serious adverse effects. This scenario has been revolutionised by the introduction into clinical parasitology of the benzimidazole compounds, praziquantel (and other schistosomicidal agents) and ivermectin for helminthiases, and the 5-nitroimidazoles for protozoan infections. An effective armamentarium against Plasmodium spp. infections, especially P. falciparum, is receding as widespread multiple drug resistance becomes commonplace. Although management of several more exotic parasitic infections, including trypanosomiasis, leishmaniasis and onchocerciasis remains unsatisfactory, several newer and relatively non-toxic preparations (including eflornithine and ivermectin) are now available, and offer optimism. However, there remains a very long way to go before a single preparation is available to combat all major protozoan and/or helminthic infections; such an agent would also need to be 100% effective when given as a single dose, safe not only in the healthy adult but also during pregnancy and lactation, stable at high ambient temperature and relatively low in cost.