Plasma levels of praziquantel decrease when dexamethasone is given simultaneously

Treatment with praziquantel for neurocysticercosis frequently induces adverse reactions due to acute destruction of parasites; these reactions are suppressed by dexamethasone therapy. However, there is controversy about the most appropriate regimen with praziquantel and dexamethasone. We studied plasma levels of praziquantel in eight patients given the drug alone or with dexamethasone. Plasma levels of praziquantel were 50% lower in the same patient when dexamethasone was given simultaneously. Dexamethasone should not be added to praziquantel therapy as preventive treatment, but should be reserved for transient therapy of adverse reactions.