Neurocysticercosis—Albendazole is now the preferred drug, but when it is not appropriate or available, praziquantel has similar efficacy. Indications for praziquantel are similar to those for albendazole. The praziquantel dosage is 100 mg/kg/d in three divided doses for 1 day, then 50 mg/kg/d to complete a 2to 4-week course. Clinical responses to therapy vary from dramatic improvements of seizures and other neurologic findings to no response and even progression of the disease. Praziquantel—but not albendazole—has diminished bioavailability when taken concurrently with a corticosteroid. Recommendations on use of both antihelminthics and corticosteroids in neurocysticercosis vary.
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Hymenolepis nana—Praziquantel is the drug of choice for H nana infections and the first drug to be highly effective. A single dose of 25 mg/kg is taken initially and repeated in 1 week.
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Hydatid disease—In hydatid disease, praziquantel kills protoscoleces but does not affect the germinal membrane. Praziquantel may be used as an adjunct with albendazole preand post-surgery. In addition to its direct action, praziquantel enhances the plasma concentration of albendazole.
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Other parasites—Limited trials showed effectiveness of praziquantel at a dosage of 25 mg/kg three times daily for 1–2 days against fasciolopsiasis, metagonimiasis, and other forms of heterophyiasis. Praziquantel was not effective for fascioliasis, however, even at dosages as high as 25 mg/kg three times daily for 3–7 days.
Adverse Reactions, Contraindications, & Cautions
Mild and transient adverse effects are common. They begin within hours after ingestion of praziquantel and may persist for about 1 day. Most common are headache, dizziness, drowsiness, and lassitude; others include nausea, vomiting, abdominal pain, loose stools, pruritus, urticaria, arthralgia, myalgia, and low-grade fever. Mild and transient elevations of liver enzymes have been reported. Several days after starting praziquantel, low-grade fever, pruritus, and skin rashes (macular and urticarial), sometimes associated with worsened eosinophilia, may occur, probably due to the release of proteins from dying worms rather than direct drug toxicity. The intensity and frequency of adverse effects increase with dosage such that they occur in up to 50% of patients who receive 25 mg/kg three times daily.
In neurocysticercosis, neurologic abnormalities may be exacerbated by inflammatory reactions around dying parasites. Common findings in patients who do not receive corticosteroids, usually presenting during or shortly after therapy, are headache, meningismus, nausea, vomiting, mental changes, and seizures (often accompanied by increased cerebrospinal fluid pleocytosis). More serious reactions, including arachnoiditis, hyperthermia, and intracranial hypertension, may also occur. Corticosteroids are commonly used with praziquantel in the treatment of neurocysticercosis to decrease the inflammatory response, but this is controversial and complicated by knowledge that corticosteroids decrease the plasma level of praziquantel up to 50%. Praziquantel is contraindicated in ocular cysticercosis, because parasite destruction in the eye may cause irreparable damage. Some workers also caution against use of the drug in spinal neurocysticercosis.
Praziquantel is safe and well tolerated in children. Recent data suggest that the drug can be given safely during pregnancy. Because praziquantel induces dizziness and drowsiness, patients should not drive during therapy and should be warned regarding activities requiring particular physical coordination or alertness.