Switching Seizure Medications: Part II

How soon should medications be changed?

The typical rule of thumb is that medications should be switched if they are ineffective.  Once a person has been on the appropriate medication for their type of seizures, and has reached the appropriate or maximum dose and is still having seizures, the medication should be changed.  Usually a second medication is added and then “titrated up” (that is adjusted in a step-wise progression) until seizure control is reached or the maximum dose of the second medication is achieved. If seizures are under control, consideration should be given to weaning the first medication.  Having said that, there are often instances when seizure control is reached with two medications used in combination and the person with epilepsy remains on two medications.  The risk of seizures and injury must be weighed against the risk of side effects.

Should medications be changed if there are side effects?

The important thing to remember about side effects is that they MAY occur, not that they will!  Medications are tested in clinical trials in large groups of persons.  Every event that occurs during the time of the trial is reported as a side effect, even if the event occurs only in one or two persons and is not conclusively determined to be a direct effect of the medication.

Often side effects occur when the medication is first initiated and may lessen or resolve over time as the person’s body “becomes used to the medication.”  A prime example is the side effect of drowsiness that occurs with oxcarbazepine and usually resolves within a week or two.  Another is the abdominal upset that can occur with ethosuximide and is managed by eating before the medication is taken.  On the other hand, intolerable side effects should result in changes of medications.

 Should generic medications be used?

As a general rule, in he treatment of epilepsy, most providers favor the use of brand name medications.  This is for several reasons:

  • there has been no testing in generic medications to determine the time before maximum concentration of the medication is reached
  • there has been no testing in special populations –these include children, the elderly and the developmentally delayed
  • bioavailability can vary, since the only requirement with generic medication is that there be 90% bioavailability between 80% and 125% of the BRAND NAME medication for the first generic formulation.  There are no formal generic-to-generic studies and therefore different generics can vary widely in their bioavailability
  • there is no testing of generic medications in patients on more than one medication, so there is no data on potential drug interactions

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