Praziquantel !
Anthelmintic against flukes and tapeworms: the drug of choice for schistosomiasis; it lets calcium in and paralyses the worm within hours.
Updated 2026-11-01
Mechanism of action
It activates a schistosome transient receptor potential (TRP) channel, so calcium floods into the worm's cells. The parasite goes into spastic contraction and its tegument (outer covering) vacuolises and breaks down, exposing its antigens to the immune system. It is weak against juvenile schistosomes, so it works less well in the acute phase.
- Activates the TRP channel of the worm tegument
- Calcium rushes into its cells
- Spastic paralysis and tegument damage
- The immune system clears the exposed parasite
Pharmacokinetics
- Absorption
- Good orally, with peak blood level in 1 to 3 hours
- Metabolism
- Extensive first-pass liver metabolism by cytochrome P450; moderate or severe liver impairment greatly raises levels
- Elimination
- Mainly via the kidney, almost all as metabolites
- Half-life
- Short: 0.8 to 1.5 hours
Indications
- Schistosomiasis due to all Schistosoma species Schistosomiasis →
- Liver flukes: clonorchiasis and opisthorchiasis
- Intestinal taeniasis (adult tapeworms)
- Neurocysticercosis with several viable cysts, together with albendazole Neurocysticercosis →
Adverse effects
Common
- Malaise, fever and headache
- Dizziness
- Abdominal discomfort and nausea
- Hives
- More effects the heavier the worm burden
Contraindications
- Ocular cysticercosis
- Use of strong CYP3A inducers such as rifampicin
- Hypersensitivity to praziquantel
Key interactions
- Rifampicin and other strong CYP3A inducers
- Lower its levels so much that they are contraindicated
- Efavirenz
- Greatly reduces its levels; the combination is avoided
- Dexamethasone and other corticosteroids
- Lower praziquantel levels
- Cimetidine, ketoconazole, itraconazole, erythromycin, ritonavir or grapefruit juice
- Raise its levels
- Albendazole
- Praziquantel raises albendazole sulfoxide levels
What is monitored
- Heart rhythm in people with arrhythmias
- Neurological status; hospital stay during treatment if there is cerebral cysticercosis
- Liver function in moderate or severe liver impairment
- Eye examination to rule out ocular cysticercosis before treatment
Administration and safety
- Oral, as doses within a single day for schistosomiasis and flukes.
- No driving or operating machinery on the treatment day or the next day.
- Grapefruit juice is avoided during treatment.
- Check the medication list: rifampicin rules it out.
Nursing care
- Before: ask about rifampicin and other CYP3A inducers, arrhythmias and liver problems.
- Watch for dizziness, headache, fever and hives; they are more common with heavy worm loads.
- In cerebral cysticercosis: the patient stays in hospital and is watched for seizures and signs of raised intracranial pressure.
- Teaching: no driving that day or the next; report palpitations or fainting.
Pregnancy and breastfeeding
Published studies and two randomised trials show no increase in major birth defects or miscarriage; little passes into milk.
Test yourself
Think of the answer, then tap the question to see it.
How does praziquantel act on schistosomes?
It activates a worm TRP channel: calcium enters, causing spastic paralysis and damaging its tegument.
In which form of cysticercosis is praziquantel contraindicated?
Ocular cysticercosis.
Why is praziquantel not combined with rifampicin?
Because rifampicin, a strong CYP3A inducer, lowers its levels so much that treatment fails.
Which liver fluke does not respond to praziquantel?
Fasciola hepatica, which is treated with triclabendazole.
Related drugs
Related conditions
← Back to the class: Anthelmintics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - PRAZIQUANTEL tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Clinical Care of Cysticercosis (Centers for Disease Control and Prevention (CDC), 2024); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 68 (McGraw Hill, 2023).
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Representative model, for educational purposes only.