Praziquantel is a broad-spectrum anthelmintic agent, specifically a pyrazinoisoquinoline derivative, used primarily for the treatment of schistosomiasis (bilharzia) and infections caused by liver flukes (clonorchiasis, opisthorchiasis) and intestinal flukes (fasciolopsiasis). It is considered the drug of choice for most trematode and cestode infections. The 600mg tablet is a standard single-dose strength used in mass drug administration programs and individual treatment in India.
Adult: Schistosomiasis: 40-60 mg/kg as a single dose or 20 mg/kg three times in one day (6-hourly). Liver/Intestinal Flukes: 25 mg/kg three times in one day (6-hourly). Tapeworms: 10-25 mg/kg as a single dose.
Note: Swallow tablet whole with water during a meal. Do not chew or crush due to bitter taste. For the three-dose regimen, doses should be taken approximately 4-6 hours apart. Patients should avoid grapefruit juice as it may interfere with metabolism.
Praziquantel increases the permeability of the cell membrane of susceptible worms to calcium ions, leading to massive contraction and paralysis of the parasite's musculature. This results in detachment from blood vessel walls (schistosomes) or gut walls (cestodes). The paralyzed worms are then dislodged and expelled from the body. The drug also causes tegumental damage, exposing hidden antigens and making the parasite vulnerable to host immune attack.
Pregnancy: Category B: Animal studies show no risk, but no adequate human studies. Avoid in first trimester. Use in second/third trimester only if clearly needed, especially in symptomatic infection. WHO recommends use in pregnant women after first trimester in schistosomiasis-endemic areas.
Driving: Patients should not drive or operate machinery for 24-48 hours after taking praziquantel due to risk of dizziness and drowsiness.
| Carbamazepine, Phenytoin, Phenobarbital | Markedly decreases praziquantel plasma levels via CYP450 induction, leading to treatment failure. | Major |
| Rifampicin | Decreases praziquantel bioavailability and plasma concentration. | Major |
| Cimetidine | Increases praziquantel plasma levels by inhibiting CYP3A4. | Moderate |
| Dexamethasone | May decrease praziquantel levels; used together in neurocysticercosis. | Moderate |
| Chloroquine | Reduces bioavailability of praziquantel. | Moderate |
Same composition (Praziquantel (600mg)), different brands: