Phenothiazine drugs – fluphenazine, chlorpromazine,
methotrimeprazine and trifluoperazine – were evaluated as modulating agents
against Brazilian chloroquine-resistant fresh isolates of
Plasmodium falciparum
. Aiming to simulate therapeutic schedules, chloroquine was
employed at the concentration used for sensitive falciparum malaria treatment
and anti-psychotic therapeutic concentrations of the phenothiazine drugs were
adopted in two-fold serial dilutions. The in vitro microtechnique for drug susceptibility
was employed. Unlike earlier reported data, the phenothiazine modulating effect
was not observed. However, all the drugs demonstrated intrinsic antiplasmodial
activity in concentrations lower than those described in the literature. In addition,
IC
50 estimates have been shown to be inferior to the usual anti-psychotic
therapeutic concentrations. Statistical analysis also suggested an increase in
the parasitaemia rate or, even, a predominant antiparasitic effect of phenothiazine
over chloroquine when used in combination.
