Medication Summary
Anticonvulsant and anti-inflammatory (steroid) medications are the basis of medical therapy in symptomatic patients. Antiparasitic drugs have not been shown to provide a consistent long-term benefit in patients with parenchymal disease and seizures.
Anticonvulsants
Class Summary
Anticonvulsants should be used in patients with seizures or who are at high risk for recurrent seizures. Patients with parenchymal calcifications carry a high risk of seizure recurrence if anticonvulsants are tapered; therefore, these patients usually remain on anticonvulsants indefinitely. In contrast, patients with active cysticerci in whom lesions resolve without developing calcification should be treated with anticonvulsants until they are free from seizures for at least one year and results of neuroimaging studies show normalization. Anticonvulsants may then be tapered. Patients with recurrent seizures should be maintained on long-term anticonvulsant therapy.
A double-blind, placebo-controlled study in 2004 compared two groups of patients with viable parenchymal cysts, with seizures being treated with anticonvulsants, to see whether anticysticercal drugs improved seizure control. During 30 months of follow-up, the proportion of patients having partial seizures was similar for the group who took albendazole and dexamethasone and those who took placebos, but the treatment group had significantly fewer seizures with generalization, and more of their intracranial lesions resolved. Except for abdominal pain, adverse effects did not differ significantly. [26]
Phenytoin, carbamazepine, and phenobarbital induce metabolism of praziquantel.
Phenytoin (Dilantin)
Widely available and inexpensive. Has significant drug interactions, and dosage should be adjusted based on therapeutic effect and serum levels. Fosphenytoin may be considered for IV administration if available because it is better tolerated than IV phenytoin, but it is considerably more expensive than phenytoin.
Carbamazepine (Tegretol)
Use if phenytoin unavailable, ineffective, or contraindicated. Anticonvulsant therapy should be used for one year after resolution of the active parasitic infection followed by a trial of treatment discontinuation if the patient remains seizure-free.
Phenobarbital (Barbital, Luminal, Solfoton)
Use if phenytoin unavailable, ineffective, or contraindicated. Interferes with transmission of impulses from thalamus to cortex of brain. Used as sedative.
Corticosteroids
Class Summary
These agents should be used immediately in patients with significant cerebral edema, mass effect, or vasculitis associated with neurocysticercosis. High doses (approximately 1 mg/kg/d of prednisone) should be used. High-dose dexamethasone (30 mg/d) should be used initially to treat cysticercal encephalitis. If cerebral edema resolves, patients may be treated with antiparasitic drugs later. Long-term courses of corticosteroids should be used in patients with subarachnoid neurocysticercosis who have meningitis, stroke, or communicating hydrocephalus and should be tapered as soon as possible based on lumbar puncture and neuroimaging results.
Long-term course of corticosteroids may also prevent shunt failure in patients with VP shunt and active disease. Patients with intramedullary spinal neurocysticercosis should be treated with steroids until resolution of cord edema. Patients receiving long-term corticosteroids should be given calcium supplementation to help counterbalance osteoporotic effects of corticosteroids.
Prednisone (Deltasone, Meticorten, Orasone)
Inexpensive, widely available, and effective. Use in patients with significant edema, mass effect, or vasculitis.
Dexamethasone (Decadron, AK-Dex)
Use in patients with cysticercal encephalitis or in patients with severe mass effect, edema, or vasculitis if preferred over prednisone.
Antiparasitics/anthelminthic
Class Summary
Albendazole and praziquantel are antiparasitic drugs used to treat neurocysticercosis. Albendazole has historically been preferred over praziquantel because of its favorable pharmacokinetics profile and efficacy. A recent study has shown that combination therapy may lead to better outcomes. [27] Both agents are cysticidal. These drugs are always administered with corticosteroids. In the presence of absolute neutropenia or elevation of transaminases more than 5 times the upper limits of the reference range, albendazole should be withheld until laboratory test results normalize. [20]
When praziquantel is administered with cimetidine to increase its bioavailability, praziquantel is probably as effective as albendazole in killing viable cysticerci.
Antiparasitic drugs are contraindicated in cysticercal encephalitis (characterized by diffuse cerebral edema), uncontrolled elevated ICP, ocular disease, and subarachnoid neurocysticercosis in close proximity to blood vessels. In all of these cases, steroids should be administered early so that the inflammatory reaction is quelled. Antiparasitic drugs, which may cause release of more antigens and stimulate more inflammation, can then be considered on a case-by-case basis.
Albendazole (Albenza)
Has no interactions with steroids or anticonvulsants. It is preferred over praziquantel because of its pharmacokinetic profile and efficacy. Parenchymal disease responds to short courses, but longer duration of therapy (months) may be needed in extraparenchymal disease. In the presence of absolute neutropenia or elevation of transaminases more than 5 times the upper limits of the reference range, albendazole should be withheld until laboratory test results normalize.
Praziquantel (Biltricide)
Increases cell membrane permeability in susceptible worms, resulting in loss of intracellular calcium, massive contractions, and paralysis of musculature. Also produces vacuolization and disintegration of schistosome tegument. This is followed by attachment of phagocytes to parasite and death. It does not cross blood-brain barrier well, only 20% of plasma levels.
Tabs should be swallowed whole with some liquid during meals. Keeping tabs in mouth may release bitter taste that can produce nausea or vomiting. The efficacy appears to be lower than that of albendazole. It works better when taken with cimetidine. Its metabolism can be induced by cytochrome P-450 (corticosteroids, phenytoin, phenobarbital). The serum level of praziquantel is lowered when any of these drugs is coadministered. It is usually considered as a second-line therapy.
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Nonenhanced CT scan of the brain demonstrates the multiple calcified lesions of inactive parenchymal neurocysticercosis.
