Seizures foscarnet

Neurotoxicity and seizures Foscarnet was associated with seizures in AIDS patients. 

Acyclovir 20 mg/kg IV every 8 hours (neonates) Alternative Therapy Foscarnet 120-200 mg/kg IV per day in divided doses every 8-12 hours neurotoxicity, phlebitis Nephrotoxicity, electrolyte imbalances, nausea/ vomiting, headache, penile ulceration, thrombophlebitis, seizures ... 

Seizures related to alterations in plasma minerals and electrolytes have been associated with foscarnet treatment. Therefore, patients must be carefully monitored for such changes and their potential sequelae. Mineral and electrolyte supplementation may be required. 

QUINOLONES FOSCARNET SODIUM Risk of seizures Unknown possibly additive side-effect Avoid combination in patients with past medical history of epilepsy. Consider an alternative antibiotic... 

The second most common adverse effect of foscarnet is symptomatic hjrpocalcemia, which may be responsible for the cardiac dysrhythmias and seizures that occur after acute overdose or excessively rapid infusion of foscarnet. Foscarnet stimulates the release of parathyroid hormone, which raised concerns about long-term administration (8). However, in a study of seven patients receiving a 14-day foscarnet induction regimen, there were no changes in calcium or phosphate metabolism (9). 

Acyclovir is the drug of choice for herpes simplex encephalitis. In patients with normal renal function, acyclovir is usually administered as 10 mg/kg intravenously every 8 hours for 2 to 3 weeks. Herpes virus resistance to acyclovir has been reported with increasing incidence, particularly from immunocompromised patients with prior or chronic exposures to acyclovir. The alternative treatment for acyclovir-resistant herpes simplex virus is foscarnet. The major toxicity of foscarnet is renal impairment, and doses must be individualized for renal function. The dose for patients with normal renal function is 40 mg/kg infused over 1 hour every 8 to 12 hours for 2 to 3 weeks. Ensuring adequate hydration is imperative. In addition, patients receiving foscarnet should be monitored for seizures related to alterations in plasma electrolyte levels. 

Clinical uses and toxicity The drug is used for prophylaxis and treatment of cytomegalovirus (CMV) infections (including CMV retinitis) and has activity against ganciclovir-resistant strains of this virus (Table 49-1). Foscarnet inhibits herpes DNA polymerase in acyclovir-resistant strains that are thymidine kinase-deficient and may suppress such resistant herpetic infections in patients with AIDS. Adverse effects include nephrotoxicity (30% incidence) with disturbances in electrolyte balance (especially hypocalcemia), genitourinary ulceration, and CNS effects (headache, hallucinations, seizures). 

Foscarnet 3.3-4 h 1.14-8 times recommended dose (average 4 times) Seizures, renal Impalmeent. One patient had seizures and died atter receiving 12.5 g daily for 3 days. 

Two patients developed tonic-clonic seizures when they were given foscarnet with ciprofloxacin. 

Both foscarnet and ciprofloxacin have the potential to cause seizures and it seems that some enhancement of this activity occurs if they are used in combination. Subsequent study in mice has shown that the combination of ciprofloxacin and foscarnet does increase the likelihood of seizures, and that the interaction is likely to be due to altered GABA-receptor binding. An interaction was not found for enoxacin and foscarnet. ... 

Fan-Havard P, Sanchorawala V, Oh J, Moser EM, Smith SP, Concurrent use of foscarnet and ciprofloxacin may increase the propensity for seizures, Ann Pharmacother (1994) 28,869-72. 

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