The effects of lithium carbonate upon subjective state changes induced by sodium pentobarbital.

Behavioral and mood changes were measured for 8 normal male subjects after oral administration of sodium pentobarbital (3 mg/kg body weight). This procedure was repeated on three occasions: firstly a drug-free condition; then a condition following two weeks of maintenance 0.7 to 1.2 MEQ/L lithium carbonate; and then another drug-free condition. Intial analyses indicated a lowering of the level of euphoria reached in the lithium pentobarbital condition below that achieved after pentobarbital alone. Examination of this effect showed that the reduction after pentobarbital plus lithium was mirrored by a reduction in the baseline for the same response items due to lithium alone. The lessening of euphoria appeared to result from a general lowering of affect due to lithium maintenance. More detailed analyses showed that the quantitative response to pentobarbital was in no case reduced by lithium condition. Certain reversal effects were also discovered in which lithium plus pentobarbital acted in the opposite direction from pentobarbital alone.