Pharmacokinetics of lithium preparations in patients

Equivalent oral dosages (800 mg, 21.6 mmol) of standard ( Lithicarb ) and sustained-release ( Priadel ) lithium carbonate preparations were administered using a randomised cross-over design to six patients receiving long-term lithium maintenance and eight healthy student volunteers. In both patients and students there were no significant differences between the two lithium preparations for plasma lithium level curves, bioavailability or total urinary excretion rates. There were no differences in peak lithium concentrations (C max) between the two preparations in both patients and students, although the times to maximal levels (T max) were delayed after Priadel in patients and volunteers. These data indicate that Priadel is a delayed-release rather than a true sustained-release preparation.