Changing prescription patterns for lithium and valproic acid in old age: shifting practice without evidence

Over the past decade, valproic acid (prescribed as divalproex in North America) has been marketed as an alternative to lithium for treating bipolar disorders. For elderly patients, however, there is no clear evidence that valproic acid is more beneficial than lithium. Moreover, the evidence for the superiority of valproic acid in treating bipolar disorders—mixed episodes and rapid cycling—has been challenged in a recent Cochrane review.1 Valproic acid has not benefited patients with manic and psychiatric symptoms in dementia, despite the growing use of the drug in the management of these conditions.2 Recently, the relatively rapid shift in prescription patterns has been questioned.3 We describe trends in the use of lithium and valproic acid in a large population of people over 65. We obtained information on drug use from the Ontario Drug Benefit Program, which provides comprehensive drug benefits to all residents aged 65 or older in Ontario, Canada. …