Effects of antipsychotic drugs on the duration of interictal psychotic episodes in patients with epilepsy

•We evaluated the effects of antipsychotic drugs on duration of IIP episodes.•The non-APD group showed a significantly shorter duration than did the APD group.•Duration of episodes was significantly longer in the APD combination group.•There was no significant difference between the FAPD group and the SAPD group.•Our findings add further perspectives on treatment protocols for IIP

Treatment protocols for interictal psychosis (IIP) of patients with epilepsy have not yet been established. We aimed to clarify the effects of antipsychotic drugs (APDs) on duration of IIP episodes.We studied 393 IIP episodes in 200 patients with epilepsy in accordance with our empirical treatment protocol. The duration of all the episodes and APD treatments were reviewed. Antipsychotic drugs were used in 338 episodes and not used in 55 episodes (non-APD group). The APDs used in the treatment of IIP episodes were divided into the following three groups: first-generation APDs (FAPD, n = 252), second-generation APDs (SAPD, n = 44), and the combination of first- and second-generation APDs (CAPD, n = 42). The non-APD group showed a significantly shorter episode duration than did the APD group (F = 6.05, p = 0.014). Among the 3 APD groups (FAPD, SAPD, and CAPD), there was a significant difference in duration of IIP episode (F = 8.65, p = 0.000). Whereas the duration of episodes was significantly longer in the CAPD group than in the other two groups, it was not significantly different between the FAPD and SAPD groups. Our findings further to clarify the nature of IIP and add further perspectives on treatment protocols for IIP.