High-dose praziquantel for neurocysticercosis: serum and CSF concentrations.

Serum and CSF concentrations of praziquantel were analyzed in 8 patients with active neurocysticercosis aged 35 +/- 16 (mean +/- sd) years, in order to determine factors that may improve the therapeutic ratio. Praziquantel was given orally at 6-h intervals for 10 days at a daily dose of 100 mg/kg. Serum concentrations were determined at 1, 2 and 4 h, and CSF concentrations at 2 h after the morning dose. Peak serum concentrations occurred between 1 and 2 h after administration. There was a trend towards a drop in serum concentration from Days 1 through 5 to 10 of therapy. A fourfold increase in oral dose led to an eightfold rise in serum and CSF concentration, indicating saturation of hepatic metabolism. There were linear correlations (p less than 0.01) between serum and CSF concentrations of praziquantel, indicating free flow across the blood-brain barrier, above an apparent threshold, which may be related to occupation of plasma protein-binding sites. The results indicate that monitoring of serum concentrations may be clinically useful.