Abstract

1. In order to examine the prophylactic interaction between lithium and carbamazepine (CBZ), 18 patients who had been treated prophylactically with a combination of lithium and CBZ (combination therapy), lithium alone (Li-therapy), or CBZ alone (CBZ-therapy) were investigated in terms of episode occurrence. 2. The results revealed that the duration of symptoms and the frequency of hospitalization per year were significantly lower in the combination therapy than in both the Li-therapy and the CBZ-therapy. 3. In 7 out of 18 patients, the best prophylactic effect was obtained during combination therapy and none of the parameters measured was definitely inferior to those measured during the two single therapies. 4. During combination therapy, serum lithium level was significantly lower than during Li-therapy in the CBZ responders, and the combination of the two drugs enabled the required concentrations of lithium to be decreased. 5. It was concluded that synergistic action and a decrease in required concentrations of lithium can be expected with the combined use of lithium and CBZ, especially in responders to CBZ.