Praziquantel is a drug used for treating certain parasitic infections, especially against tapeworms and roundworms, in combination with other drugs. This article will provide readers with some information about Praziquantel use, as well as dosage, and potential side effects.
1. Indications and contraindications for Praziquantel use
1.1 Indications
Praziquantel is effective on a wide range of fluke and tapeworm species, and is often used to treat infections by:
• Schistosomas (S.japonicum, S. haematobium, S. mekongi, S. mansoni). This drug can be used for both acute and chronic periods, including neuroschistomiasis. Praziquantel is the main treatment method for schistosomiasis in humans, and often effective in only one dose.
• Clonorchis sinensis (small Chinese fluke), Opisthorchis viverrini (Southeast Asian liver fluke).
• Other types of tapeworm: Heterophyes heterophyes (intestinal fluke), Fasciolopsis buski (intestinal fluke), Paragonimus westermani (lung fluke). Praziquantel is not effective for Fasciola hepatica (sheep liver fluke).
• Human pathogenic tapeworms: Taenia saginata (beef tapeworm), T. solium (pork tapeworm), Dipylidium caninum (tapeworm in cats and dogs), Hymenolepsis nana (dwarf tapeworm), Diphyllobothrium latum (fish tapeworm).
• Praziquantel can be combined with pyrantel to treat roundworm infection.
1.2 Contraindications
• Hypersensitivity and allergy to components of Praziquantel
• Cysticercosis in the eyes
• Cysticercosis in the spinal cord
2. Dosage and administration route of Praziquantel
2.1. Way of using Praziquantel
• Praziquantel can be consumed orally during mealtime, usually for 3 times per day (4 to 6 hours apart).
• Swallow each tablet or the divided dose with a glass of water; avoid chewing or holding it in your mouth as its bitter taste can induce vomiting.
• If the patients have difficulties swallowing the tablet, it can be ground and mixed into food. However, it has to be taken in 1 hour after mixing.
• The dosage can vary depending on the patient’s health status, weight, and response to the medication. The tablets are scored to enable precise splitting for accurate dosage.
• Avoid drinking pomelo juice or eating pomelo after taking the drug. Pomelo juice can increase the risk of Praziquantel side effects.
To reduce the risk of nervous system damage in patients with neurocysticercosis, use this drug in combination with dexamethasone 6-24 mg/day, or prednisolone 30 - 60 mg/day.
2.2. Dosage for adults and children
• Schistosomas: Use for both adults and children over 4 years old: 60 mg/kg/day divided into 3 doses, or 40 mg/kg/day divided into 2 doses of 4 - 6 hours apart (or a single dose of 40 - 60 mg/kg/day). Administered in 1 day.
• Small liver fluke Clonorchis sinensis and Opisthorchis viverrini: For adults and children over 4 years old: administer in 1-2 days in a single dose of 40 - 50 mg/kg/day, or 75 mg/kg/day divided into 3 doses.
• Other types of fluke (Fasciolopsis buski, Metagonimus yokogawai, Heterophyes heterophyes): 75 mg/kg/day, divided into 3 doses.
• Nanophyetus salmincola: 60 mg/kg/day, divided into 3 doses.
• Paragonimus westermani: administered in 1-2 days, 25 mg/kg/dose x 3 doses/ngày.
• P. uterobilateralis: 25 mg/kg/dose x 3 doses/ngày, administered in 2 days
• Tapeworms: mature stage in the intestine ( fish tapeworm, beef tapeworm, dog tapeworm, pork tapeworm): 5 - 25 mg/kg, administered in one single dose.
• Hymenolepis nana: 25 mg/kg/dose, administered in one single dose.
• For parasites at larval stage inside the tissues: 50 mg/kg/day, divided into 3 doses, administered in 15 days for pork tapeworm.
• Pork tapeworm neurocysticercosis: 50 - 100 mg/kg/day, divided into 3 doses, administered daily for 30 days.
3. Side effects
Most side effects are caused by the release of parasitic contents upon their death, which triggers the immune response. The more severe the parasitic infection, the more frequent and serious the side effects can be. The unwanted effects of Praziquantel are quite common but often mild and can resolve quickly. However, remember to contact your doctor if you encounter any unusual, prolonged, or serious side effects.
• Central nervous system: Side effects include dizziness, headache, and discomfort. Patients can also face sleepiness, exhaustion, high fever, convulsion, or increased intracranial pressure. Most patients with neurocysticercosis would have to deal with side effects associated with the central nervous system due to parasite cell death. These side effects can be life-threatening but are resolvable using corticosteroids. All patients with neurocysticercosis are recommended for long-term hospitalization.
• Digestion system: About 90% of patients encounter stomachache, bloating, nausea, and vomiting. Diarrhea can also occur and worsen; sometimes together with light fever and blood in stool.
• Liver: Asymptomatic and transient elevated liver enzymes (AST and ALT) are frequently reported (up to 27% of cases). To date, no case of symptomatic liver damage has been reported.
• Body reactions: Urticaria, rash, itching, and increased eosinophil level.
• Other organs: Back pain, muscle pain, joint pain, fever, sweating, arrhythmia, and hypotension.
Severe allergic reactions are rare and only a few anaphylactic shock cases have been reported over the world. However, it can be life-threatening if not treated in time. Contact your doctor immediately if encountering any of these symptoms: shortness of breath, increased heart rate, edema….
4. Precaution when using Praziquantel
• Praziquantel can cause dizziness and nausea during treatment and up to 24 hours after administration. Avoid driving, operating machinery, or doing any tasks requiring alertness during this period. Alcohol or other stimulants might increase side effects.
• Neurocysticercosis patients need to be hospitalized for treatment and monitoring.
• Before using the medication, patients should inform doctors about their medical history. Caution is needed with arrythmia patients, their heart rate must be monitored during the treatment period. Caution when using this drug for patients with convulsion and epilepsy history.
• Praziquantel is metabolised in the liver. In case of enlarged liver due to schistosomiasis, drug metabolism might reduce, leading to higher and prolonged level of unmetabolised drug.
• Exercise caution with patients over 65 years old, or patients with kidney failure, as their liver function might reduce, resulting in higher chances of drug toxicity.
• Pregnant women: Praziquantel can cause miscarriages in mice at doses that triple the human dose. A study shows that praziquantel treatment in pregnant women does not increase the rates of premature birth, stillborn, underweight infants, or birth defects. However, using this drug is still not recommended due to the lack of evidence. During pregnancy, Praziquantel should only be used after consulting a doctor to carefully consider its benefits and risks for treatment.
• Breast-feeding mothers: A small amount of Praziquantel can get into breastmilk, though it is unclear whether or not this is harmful to the baby. It is recommended to stop breastfeeding and discard breast milk during the day of treatment and within 72 hours after stopping the medication.
5. Drug interactions
Pranziquantel is metabolized by a liver enzyme - cytochrome P450 (CYP450). Therefore, using Praziquantel with drugs that alter CYP450 function can increase or decrease Praziquantel level in blood plasma. A lower Praziquantel level can reduce its effectiveness.
• Do not use Rifampicin with Praziquantel: Rifampicin is a strong inducer of CYP450, resulting in a drop of Praziquantel to below its effective concentration. Studies have pointed out that in some cases, Rifampin can decrease Praziquantel level to the undetectable point.
• Cloroquin: Decrease Praziquantel level
• Carbamazepine and phenytoin is reported to reduce the bioavailability of Praziquantel.
• Cimetidine can increase Praziquantel bioavailability.
The way of using Praziquantel can determine its effectiveness or counter-effectiveness in medical treatment. Therefore, patients should consult their doctors or pharmacists for this drug use.
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