OBJECTIVE:

To examine the effects of sodium polystyrene sulfonate (SPS) on serum potassium (K) concentrations in mice pretreated with parenteral lithium (Li).

METHODS:

A placebo-controlled murine model trial of SPS therapy following IV Li was performed. Sixty male CD-1 mice weighing 18-22 g were administered either IV LiCl (125 mg/kg) or a control solution (normal saline). Half of the mice in each of these groups were then given orogastric water 20, 40, 90, 150, and 210 minutes after LiCl or normal saline; the other half received SPS (5 g/kg/dose) at equivalent times. Subgroups of each of these four groups were sacrificed at one, two, and six hours after pretreatment and the serum was analyzed for K concentration. Serum K concentrations for the various groups were compared with analysis of variance and Newman-Keuls tests for the comparison of multiple means.

RESULTS:

A statistically significant reduction of serum K concentrations occurred in the animals that received SPS treatment following either IV saline or LiCl solutions. The degree of K reduction that resulted from the combination of LiCl and SPS treatment (35% reduction at six hours, compared with the placebo-treated controls) was larger than that which resulted from either IV Li with oral water (15% reduction) or IV saline with oral SPS (20% reduction).

CONCLUSIONS:

These findings suggest that development of hypokalemia may represent a potential limitation in the use of SPS in the treatment for Li toxicity.