Reversal of chloroquine resistance with desipramine in isolates of Plasmodium falciparum from Central and West Africa.

Twenty freshly isolated strains of Plasmodium falciparum from non-immune and semi-immune patients infected in Central and West Africa were tested for in vitro drug sensitivity to chloroquine alone and to a combination of chloroquine and desipramine without prior adaptation to continuous culture. Combination of desipramine at 625 nmol/litre and chloroquine reversed resistance totally (IC50 less than 100 nmol/litre) in all 14 chloroquine-resistant isolates. No effect on chloroquine sensitivity was noted in the 6 chloroquine-sensitive isolates. These observations provide additional evidence that reversal of chloroquine resistance in the presence of desipramine is not a phenomenon unique to culture-adapted strains and that desipramine may exert the same potentiating effect in vivo, provided that effective plasma concentration can be attained without serious side-effects.