Dexamethasone Therapy in Patients With Brain Tumors - A Focus on Tapering

Ann E. Nahaczewski; Susan B. Fowler; S. Hariharan


J Neurosci Nurs. 2004;36(6):340-343. 

In This Article

Drug Interactions

Phenytoin, an antiepileptic medication frequently prescribed for seizure prophylaxis in patients following neurosurgery, has been shown to decrease the serum half-life of dexamethasone by increasing its metabolism. This interaction may account for the variations in the optimal dexamethasone dose in a large number of brain tumor patients receiving prophylactic anti-epileptic medications. Phenobarbital, another antiepileptic medication, has also demonstrated a similar effect on dexamethasone. Both of these agents are potent inducers of the hepatic microsomal enzyme system, which would explain their effect on dexamethasone metabolism. Hence, newer anti-epileptic drugs with no hepatic enzyme inhibition, such as gabapentin and levetiracetam, may be preferable for patients who need seizure prophylaxis. The interaction of dexamethasone and other anti-epileptic drugs has not been well studied. Careful monitoring and dose adjustments may be required to achieve therapeutic drug concentrations (Gattis & May, 1996).