Comparison of serum levels of two sustained- release preparations of lithium carbonate

SummaryConcentrations of lithium in serum were compared during treatment of 18 chronic schizophrenic patients with 2 sustained-release forms of tablet containing lithium carbonate (‘Priadel’ and Lithium'Phasal’). Doses were given once daily at 7pmor8am. ‘Priadel’ gave higher concentrations at 9 pm after dosage at 7 pm, and higher at 12 noon when the drugs were given at 8 am. When the drugs were given at 7 pm mean values between 9 am and 6 pm were similar for the two formulations.In general, the two preparations were satisfactory sustained-release forms of a lithium salt. ‘Phasal’ might have been slightly less likely to give side-effects than ‘Priadel’, but this disadvantage with the latter drug might be avoided by giving it later at night. The findings supported the view that for once-a-day administration it is better to give sustained-release forms of lithium salts at night rather than in the morning, so that any peaks in serum concentration should be during sleep, but twice-a-day dosage would be preferable.