Dr. Murai Éva szerk.: Parasitologia Hungarica 26. (Budapest, 1993)

Table 1 Treatment of chloroquine resistant Plasmodium falciparum malaria Treatment No.of Fever on Initial Cure Resistance Parasite Fever Body groups patients admission parasite rate to treatment clearance clearance weight (Mats and meths) :ount( p./ul) % in vivo time (h) time (h) (kg) la 10 38.2 12.800 40 60 68.0 44.0 52.0 (RI,RII,RIII) lb 10 38.6 16.750 60 40 66.0 42.0 53.5 (RI,RII,RIII) 2a 10 37.8 10.790 0(100)* 100(0)* 57.4 35.8 50.0 2b 15 38.3 29.380 100 0 55.1 36.7 54.0 3 10 38.8 13.850 90 10 92.8 69.1 51.5 4 9 38.5 8.324 33.3 66.6 72.0 48.8 50.0 The patients of group 2a were treated first with chloroquine + verapamil. Those failing to respond to that therapy were then treated with a combination of quinine + quinidine (This means that the patiens included in group 2a can be found in groups la and lb) DISCUSSION The spread of resistance to antimalarial drugs can cause an escalating problem in the treatment of that life-threatening disease. This is a major concern for researchers looking for a new antimalarial drug or for a drug combination of existing drugs. This multiple drug resistance encountered in malaria treatment appears to be similar to the multiple drug resistance (MDR) phenomenon which occurs in neoplastic cells (Jacobs et al. 1988). Verapamil, a calcium channel blocking drug, used mainly as a coronary vasodilator, has been shown to reverse MDR in cultured cells by inhibiting the active efflux of the drugs from the resistant cells. Martin et al. (1987) showed that verapamil at constant subinhibitory concentrations in vitro reduces the IC50 of resistant clones of P.f. to that of the sensitive clone, whereas the IC50 of the sensitive clone remained unchanged in the presence of similar concentrations of verapamil (Martin et al. 1987). The in vivo data show that in the groups where verapamil was added to chloroquine, a larger number of patients were cured than in the group treated with chloroquine alone; however, these differences are not statistically significant. All cases showing in vivo resistance to chloroquine (10 patients) were