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

  1. 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.
  2. To determine the change in total and free VPA concentration required to achieve maximal effect on PPR in patients with photosensitive epilepsy.

Hypothesis

  1. 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.
  2. 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