Intravenous valproate loading in acutely manic and depressed bipolar I patients

Recently, valproate has emerged as a drug of primary choice for the treatment of acute mania, especially mixed mania and, partially, rapid cycling. Because of its relative safety, it can be administered in high doses as an oral loading therapy, with approximately 60% to 70% of patients showing a favorable response. Here we report on seven bipolar I patients, two of which have euphoric mania, three have a mixed manic state (including one patient with ultra-rapid cycling and one with very prominent depressed features), and two have solely depressed mood. All but one of the manic patients showed a rapid and favorable response to intravenous valproate loading, which built up sufficient blood levels that were maintained by subsequent oral treatment. Of the two patients with solely depressed mood, however, one experienced only minor benefits and the other showed no change in the depressive symptomatology. Intravenous valproate was tolerated without problems and also led to a drastic reduction in and eventual withdrawal of benzodiazepine treatment in two cases. All of the patients showed a drastic remission of mania with valproate blood levels at or only slightly above 50 microg/mL (blood drawn 12 hours after last application). It is interesting to note that one patient who was previously nonresponsive to oral valproate loading responded well to intravenous valproate. Besides the obvious efficacy and safety of this treatment regimen, these findings may also imply that a difference in pharmacokinetics with intravenous loading may result in a quick saturation of plasma-binding proteins, and hence, peak concentrations of valproate may be reached rapidly, which could contribute to the beneficial action, even in patients previously nonresponsive to oral valproate.