praziquantel
anthelmintic· Brands: Biltricide, Cysticide, Distocide, DroncitPO
Mechanism of action
Praziquantel increases the permeability of trematode and cestode cell membranes to calcium ions, causing depolarisation, contraction, and paralysis of the parasite. This leads to detachment from host tissues and death, often with expulsion via host immune responses.
Pharmacokinetics
Praziquantel is rapidly absorbed after oral administration, but undergoes extensive first-pass metabolism to inactive metabolites. Peak plasma concentrations occur within 1 to 2 hours. The half-life is approximately 1 to 2.5 hours. Metabolites are excreted in urine and bile. Food, especially high-carbohydrate meals, may increase absorption and reduce presystemic metabolism.
Indications & dosing
Schistosomiasis due to Schistosoma mansoni or S. haematobium
Take with food if possible to reduce nausea. May repeat after 4-6 weeks if response incomplete.
- adult · PO: 40 mg/kg single dose · Take with food if possible to reduce nausea. May repeat after 4-6 weeks if response incomplete.
Schistosomiasis due to S. japonicum or S. mekongi
Single oral dose. Repeat if necessary.
- adult · PO: 60 mg/kg single dose · Single oral dose. Repeat if necessary.
Neurocysticercosis (adjunctive therapy)off-label
Used with corticosteroids and anticonvulsants. Monitor for raised intracranial pressure.
- adult · PO: 50 mg/kg/day TID for 15 days · Used with corticosteroids and anticonvulsants. Monitor for raised intracranial pressure.
Taeniasis (Taenia saginata or T. solium infection)
Single dose. May be repeated after 2 weeks if needed.
- adult · PO: 10 mg/kg single dose · Single dose. May be repeated after 2 weeks if needed.
Hymenolepiasis (Hymenolepis nana infection)off-label
Single dose, repeat after 2 weeks up to 2 times. Approval varies by region.
- adult · PO: 25 mg/kg single dose · Single dose, repeat after 2 weeks up to 2 times. Approval varies by region.
Contraindications & precautions
- Ocular cysticercosis · Risk of irreversible retinal damage from inflammatory reaction to dying cysts.
- Hypersensitivity to praziquantel · Anaphylactic reactions have been reported.
- Take praziquantel with a meal (especially a fatty meal) to enhance absorption.
- Caution in hepatic impairment: reduce dose or monitor closely, as metabolism is reduced.
- In neurocysticercosis, consider corticosteroid cover to reduce inflammatory reaction around dying cysts.
- Avoid concurrent use with rifampicin, as it significantly lowers praziquantel plasma concentrations.
Adverse effects
- Abdominal pain
- Headache
- Dizziness
- Nausea and vomiting
- Seizuresserious
- Hypersensitivity reactions (e.g. urticaria, anaphylaxis)serious
Renal & hepatic adjustment
- Hepatic impairment (mild): No dose adjustment required.
- Hepatic impairment (moderate): No dose adjustment required, but monitor for adverse effects.
- Hepatic impairment (severe): Use with caution; consider reducing the dose and monitor liver function.
Monitoring, pregnancy & toxicity
- Stool or urine examination for ova · Before treatment and 4 weeks after
- Resolution of symptoms · During and after treatment
- Liver function tests (ALT, AST) · In patients with hepatic impairment, before and during treatment
- Adverse effects (nausea, headache, dizziness, abdominal pain) · During treatment
- Pregnancy: Use only if clearly necessary, especially in the first trimester. For schistosomiasis, consider deferring treatment until after delivery if the condition is not urgent; if treatment is required, it may be given after the first trimester.
- Toxicity: Gastrointestinal effects (nausea, vomiting, abdominal pain) · Supportive care; consider antiemetics.
- Toxicity: Central nervous system effects (headache, dizziness, drowsiness, seizures) · Supportive care; treat seizures with benzodiazepines (e.g., diazepam).
- Toxicity: Hypotension · IV fluids and vasopressors if needed.
Clinical notes
Praziquantel is used for schistosomiasis, hepatic and intestinal flukes, and tapeworm infections. It should be taken with food to enhance bioavailability. Tablets may be divided or crushed for children. Common adverse effects include abdominal discomfort, nausea, headache, and dizziness. Caution is needed in patients with ocular cysticercosis, as killing the parasite can provoke inflammation. It is safe in pregnancy but should be used with caution. Dose regimens vary by infection and species, so consult local guidelines.
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BNF; local formulary