Clinical trial methodology in intestinal parasitic diseases.

The high prevalence of intestinal parasitic infections as an index of underdevelopment, especially in tropical countries, is related to poverty, poor housing, lack of sanitation, malnutrition, and ignorance. The effects are lowered work capacity, physical and mental retardation, leading to recurrences and exacerbations of the parasitism and malnutrition. The most prevalent parasites, methods of detection by specific tests in patients in clinical trials involving antiparasitic drugs are dealt with. How and by whom investigations of new drugs should be undertaken, the need for a basic knowledge of parasitology and techniques of the discipline, of biostatistics, and use of such controls as randomized allotment to treatment groups, placebo administration, and double-blind assessments are emphasized. The justification for undertaking an evaluation of an antiparasitic drug is predicated on the demonstration of safety in exhaustive in vitro and animal studies and of the drug's potential superiority as to efficacy and lower incidence of unwanted side effects, as compared with existing agents. Tolerance and dose-range studies should be conducted in male adult hospitalized patients under close supervision. The evaluation of amebicides in clinical trials, as well as of anthelmintics, is considered in terms of differentiation and reproductive habits of specific causative agents and tests for detecting their elimination to determine improvement under drug therapy. The problem of reinfection, particuarly of nonhospitalized patients under the adverse conditions of life, is stressed.