Relationship between dosage and response to lithium prophylaxis in recurrent depression

The authors analyzed the results of a multihospital collaborative study on the effectiveness of lithium prophylaxis in recurrent depression in terms of dosage and found that serum lithium levels between 0.5 and 0.7 mEq/liter and doses below 1000 mg/day were relatively ineffective in preventing recurrences. Serum lithium levels between 0.8 and 1.0 mEq/liter and doses above 1000 mg/day were associated with a relatively low failure rate. The authors discuss the relevance of these findings to current prescription guidelines for lithium carbonate.