The Ups and Downs of Oral Lithium Dosing

As a mood-stabilizing agent, lithium has a long history of documented efficacy as well as risksassociated with its use. Relative to other psychiatric medications, lithium exhibits a number of uniquepharmacokinetic properties. The use of in vivo nuclear magnetic resonance spectroscopy of the 7Liisotope has immense potential to provide an improved understanding of the pharmacokinetic basis oflithium response and nonresponse. The conventional use of orally administered immediate-releasepreparations of lithium salts in psychiatry is associated with high postabsorptive blood lithium concentrationsand trough lithium concentrations in later phases of lithium elimination. These ups anddowns of blood lithium concentrations are associated with acute lithium toxicity and symptomaticstates, respectively. The use of slow-release lithium formulations represents a long available means ofdiminishing the postdose variation in serum lithium concentrations. A significant need exists for headto-head comparisons of the pharmacokinetics and clinical response relationships for slow-release andimmediate-release lithium formulations.