Valproic acid has been shown to be effective in migraine prophylaxis.
Its method of action is believed to be the inhibition of gamma-aminobu
tyric acid transaminase. The therapeutic dose needed to prevent migrai
ne headaches has been examined in several studies, yet the optimum dos
e has not been found. In this case report, valproic acid was given to
a 24-year-old woman with chronic headaches at 1000 mg per day. Her hea
daches resolved for 2 months. She tapered herself off of the medicatio
n, and her headaches returned. She was restarted at 500 mg per day of
valproic acid and again, her headaches resolved. She preferred being o
n the lower dose which she found as effective as the higher dose. Her
case makes two interesting points. The first is that lower dosages of
valproic acid may be as effective as higher ones in headache prophylax
is. The second is that more studies looking at dose ranges are needed
to correlate effectiveness with daily requirements.