Effects of antiepileptic drug characteristics on medication adherence

To determine whether antiepileptic drug (AED) characteristics are associated with medication adherence.

We reviewed pharmacy and clinical records of 108 patients with epilepsy from the indigent care program at Shands-Jacksonville. We calculated the mean medication possession ratio (MMPR) for each AED. Using univariate analysis, we determined whether differences exist in the MMPR of various AEDs. We also determined whether the MMPR differs accordingly to the use of mono- or combination therapy, dosing frequency, release-type, or brand-name formulation. We employed multivariable analysis to determine if these differences persisted in the context of other demographic and clinical variables.

Mean medication possession ratio was higher (better) when using older AEDs, in monotherapy, and with more frequent dosing intervals. These variables remained significant on multivariable analysis.

Our findings contradict some commonly held beliefs on medication adherence and suggest that specific AED characteristics may be superseded by factors such as overall patient satisfaction with the drug regimen.