Clinical Trial: Effect of Valproic Acid Concentration on Photic Response
Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: Effect of Small Changes in Plasma Valproic Acid Concentration on the Photoparoxysmal Response
Brief Summary: We are trying to learn if small changes in the amount of a valproate in the blood (given through an IV) will change the way the brain reacts to flashing lights.
Detailed Summary:
Photosensitive epilepsy is a form of epilepsy that is considered to have a genetic basis in most instances. It is a reflex type of epilepsy. Patients with this condition exhibit epileptic activity patterns (called photoparoxysmal response-PPR) on their EEG during intermittent photic stimulation with certain flash frequencies.
Specific Aims
- To determine the extent of the pharmacodynamic effect of small changes in total and free VPA concentration via constant infusion of intravenous sodium valproate within the same photosensitive epilepsy patient.
- To determine the change in total and free VPA concentration required to achieve maximal effect on PPR in patients with photosensitive epilepsy.
Hypothesis
- Valproic acid (VPA) demonstrates differential pharmacodynamic effect on PPR with small changes in VPA concentration (5-20 mg/L changes in total, or 0.5 to 2 mg/L changes in free VPA) within the same patient. In essence, the VPA concentration-response curve in patients with photosensitive epilepsy is relatively steep.
- Intravenously-administered VPA will demonstrate a reduction in standard photosensitive range (SPR) or abolition of PPR for at least 80% of patients studied, when the entire range of free VPA concentrations is considered.
Photosensitivity, defined as a PPR on intermittent photic stimulation (IPS), is found in approximately 5% of all epileptic patients. Markedly photosensitive patients are usually sensitive to IPS within clearly defined limits of flash frequency (mostly between 10-30 Hz). This photosensitivity range, the diffe
Sponsor: Vanderbilt University
Current Primary Outcome: Analysis of total change in SPR from baseline to highest VPA conc., for each patient, averaged across patients, determines overall efficacy of VPA. [ Time Frame: At the start of EEG monitoring/drug infusion, and also on an hourly basis thereafter ]
Original Primary Outcome: Same as current
Current Secondary Outcome:
Original Secondary Outcome:
Information By: Vanderbilt University
Dates:
Date Received: February 1, 2008
Date Started: December 2007
Date Completion:
Last Updated: March 21, 2011
Last Verified: March 2011