Clinical Evaluation of Antimalarial Drugs

Abstract

We have analyzed the clinical data of 189 patients with malaria to establish antimalarial regimens in Japan. The causative parasite species were Plasmodium falciparum in 56 cases (30%), P. vivax in 132 (70%) and P. malariae in 1 (1%). The outocmes of malaria cases are as follows: Cure rats in falciparum and vivax malaria are 86% and 91%, respectively. Two patients died of falciparum malaria and recurrence occurred in 6 cases (11%) of falciparum malaria. Relape was seen in 12 (9%) of vivax malaria. Chloroquine was most frequently used among antimalarial agents (in 123 cases, 65% of the total) for suppressing acute attacks. The efficacy of chloroquine was evaluated by classifying each case into three groups; chloroquine alone in group one, chloroquine in combination with other an timalarials in group two and other antimalarials except chloroquine in group three. The cure rate among each group is about 80% and there is no difference among them. However, it is noticable that recurrence occurred when patients were treated with a combination of chloroquine and quinine. We have found a similar result as this in another old report in Japan.
Primaquine is effective for eliminating hepatic tissue schizonts but in this study, relapse occurred in 12 cases of vivax, although primaquine had been used in 10 out of 12 cases. In primaquine group, relapse occurred at a similar rate between chlorquine and Fansidar cases. Further studies are needed to decide whether a larger dose of primaquine is appropriate for treatment of vivax malaria.
Recovery periods from fever and parasitemia were comparied between chloroquine and Fansidar cases. Chloroquine was superior in eliminating the fever attack by one day earlier than Fansidar was. But the period of schizont elimination was similar among these two groups.
Concerning the current status of malaria in Japan, the first problem is that the registration of chloroquine has been revoked and so it is not marketed any more in our country. This is because the Government and the drug companies felt responsible for the side effect, chloroquine retinopathy. But physicians can obtain this drug from the Study Group for Tropical Diseases which has been organized since 1981. Chloroquine, quinine, Fansidar and primaquine are available for only treatment not for chemoprophylaxis of malaria.