CI-564, a 1:1 mixture of cycloguanil pamoate (CI-501) and 4,4′-diacetylaminodiphenyl sulfone (CI-556), was evaluated as a therapeutic agent against blood-induced infections of the Chesson strain of Plasmodium vivax. With a dose of 5 mg per kg of body weight given intramuscularly, cure was effected in each of two volunteers infected with the chlorguanide-sensitive strain. Clearance of patent parasitemia required 3 to 4 days. In two other volunteers infected with the chlorguanide-resistant strain, the clinical and parasitologic courses were modified, but parasitemia was not cleared after 14 and 28 days.
Present address: Department of Pharmacology, Louisiana State University School of Medicine, New Orleans, Louisiana.