Theophylline precipitated alterations of lithium clearance

The effect of steady state therapeutic theophylline serum levels on lithium clearance was investigated. A significant increase in lithium clearance occurred with the administration of theophylline. Despite considerable intersubject variability, a direct lithium clearance estimation method demonstrated a mean increase of 30% with the addition of theophylline. The concomitant use of lithium and theophylline potentially may alter lithium levels sufficiently to result in manic or depressive relapses in patients receiving lithium prophylactically.