Reduced valproate plasma levels possible after introduction of efavirenz in a bipolar patient

Authors


  • The authors of this paper do not have any commercial associations that might pose a conflict of interest in connection with this manuscript.

Michael Saraga, Département Universitaire de Psychiatrie Adulte, Site de Cery, CH-1008 Prilly, Lausanne, Switzerland.
Fax: +41 21 643 62 54;
e-mail: michael.saraga@inst.hospvd.ch

Abstract

The case of a bipolar patient with concomitant multidrug addiction is described who presented a decrease in valproate plasma level of more than 50% shortly after antiretroviral therapy was initiated. Despite important dose augmentations of up to 4 g/day, plasma levels were difficult to raise to the target concentration of 50 mg/dL. The possible mechanisms underlying the observed pharmacokinetic changes are discussed: (i) a uridine diphosphate-glucuronosyl transferase induction by efavirenz; and (ii) a plasma protein displacement of valproate by efavirenz with subsequent increased elimination of the free fraction.

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