The Urinary Excretion and the Antimalarial Activity of CI-501 (Cycloguanil-Pamoate, Camolar®) Against Vivax and Falciparum Malaria

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  • Laboratory of Parasite Chemotherapy, National Institute of Allergy and Infectious Diseases, National Institutes of Health, NIH Malaria Project, U.S. Penitentiary, Atlanta, Georgia


The repository preparation of the dihydrotriazine metabolite of chlorguanide, known as CI-501 (cycloguanil-pamoate, Camolar®) was studied for its urinary excretion by man in 20 inmate volunteers and its antimalarial activity in a total of 36 volunteers.

The excretion studies revealed that the rate of excretion of the drug was related directly to particle size. The drug in the form of smaller crystals was excreted at a faster rate than when it was in the form of larger crystals. At 32 to 36 weeks, approximately 90% of the former but only 65% of the latter had been excreted.

Our results indicate that as long as drug is present, inferred by its excretion in the urine of medicated volunteers, protection against patent malaria infection obtains. Barring local reaction at the site of the injection which results in increased absorption and therefore a faster excretion of the drug, the average minimum duration of protection of a single 350 mg intramuscular injection against vivax or falciparum malaria was found to be approximately 32 to 36 weeks or about eight to nine months.

Author Notes

Present address: Cytology Section, LPC, NIAID, NIH, P.O. Box 190, Chamblee, Georgia.

Laboratory of Parasite Chemotherapy, NIAID, NIH, Bethesda, Maryland.

Present address: Department of Medicine, University Hospital, Syracuse, New York.