Praziquantel

Praziquantel is a chinolin derivative and induces a rapid contraction of schistosomes by a specific effect on the permeability of the cell membrane. The medicine further causes vacuolization and disintegration of the schistosome tegument. The effect is more marked on adult than on young worms.

Praziquantel is effective against most trematodes pathogenic for humans, such as:

• Schistosoma haematobium, Schistosoma mansoni, Schistosoma japonicum, Schistosoma intercalatum;
• Other species of trematodes such as liver flukes like: Clonorchis sinensis, Opistorchis viverrini;
• Lung flukes such as Paragonimus westermani.

In vitro experiments enabled to define the mode of action of praziquantel: from 0.4μg/ml, an immediate contraction is observed, followed by an immobilization of the parasite as soon as it is in contact with the product solution. An intense vacuolization of the schistosome tegument occurs.

Praziquantel is rapidly absorbed after oral administration. Maximum serum concentration is achieved 1-3 hours after intake. The active principle is rapidly and completely metabolized, the elimination half-life of unchanged praziquantel in serum being from 1–1,5 hours. Over 80% of the dose administered is eliminated by the kidneys within 4 days, 90% of this amount within the first 24 hours.

In breastfeeding women, the plasma concentrations of praziquantel are on average 4 times higher than those found in milk. Only 0.0008% of the dose administered is eliminated in milk.

The excretion of praziquantel (approximately 80% is excreted by the kidney) may be delayed in patients with impaired renal function.

In case of hepatocellular insufficiency, reduced metabolism of praziquantel may lead to an increase in its plasma half-life.

Not applicable.