Once-daily versus twice-daily vigabatrin: Is there a difference? The results of a double-blind pilot study

Purpose: Vigabatrin (VGB) has been approved in Europe and is prescribed for either once or twice-daily administration. This choice has been based on t he pharmacodynamic activity of VGB. The purpose of this study was to compar e the efficacy and tolerability of these two different medication regimens. Methods: The study design was a double-blind randomized two-period cross-ov er study in adults who had responded to add-on VGB for previously uncontrol led seizures. Each study period consisted of three months. Patients were ma intained on the same daily dose of VGB to which they had demonstrated a cli nical response. In addition to the primary efficacy criteria of seizure fre quency on the two treatment regimens, this study included blinded ratings o f overall efficacy and "well being" by both physician and patient. The prim ary tolerability criterion was the reported incidence of adverse events by phase. Results: Fifty patients were initially entered into the study, and 13 patie nts withdrew before completion, only one reported as due to an adverse even t. Then was no statistical difference in seizure frequency or the tolerabil ity of the medication. Blinded physician and patient rating scales for seiz ure control, and patient well being showed a nonstatistical trend toward on ce-daily administration as compared with twice-daily administration. Conclusions: This clinical study provides support for the pharmacological e vidence that this preparation may be administered on a once or twice daily basis, depending on the individual patient's preference, total dosage and c o-medication.