[Case of schizophrenia in which depressive and negative symptoms relapsed on switching from oral risperidone to...

I report a case of schizophrenia in which depressive and negative symptoms relapsed on switching from oral risperidone to risperidone long-acting injection (RLAI). The patient, with a 31-year history of schizophrenia, did not fully understand his disease. Therefore, adherence to medication had been extremely poor. The discontinuation of medication led to the recurrence of the disease. After hospital treatment, he was discharged to a group home. From then, the disease had been kept in remission by risperidone at 4 mg/day, and RLAI was introduced for the purpose of further social reintegration and QOL improvement. After starting RLAI at 25 mg, however, a stiff expression and irritability appeared. Therefore, RLAI was increased up to 50 mg, but depressive and negative symptoms relapsed. Subsequently, RLAI was discontinued and oral risperidone was re-administered, and the above mental symptoms improved in a relatively rapid manner. The difference in the ratio of plasma and brain concentrations between each active moiety, risperidone and 9-OH risperidone (paliperidone), resulting from the difference in administration routes, was suggested to be involved as the main factor. In this case, it is likely that positive symptoms did not relapse because plasma concentrations of the active moiety itself were well maintained by introducing RLAI. However, depressive and negative symptoms relapsed possibly as a result of reduced affinity for the alpha2A receptor with relatively decreased plasma concentrations of 9-OH risperidone when compared to oral administration. Another possibility is that negative symptoms were secondary induced by excess administration of antipsychotics, but there has been no such report on RLAI so far. For the reason noted above, careful follow-up is considered necessary when switching from oral risperidone to RLAI because mental symptoms might get worse.