[Risperidone intoxication in a patient with a genetic predisposition as "poor [non]metabolizer"].

OBJECTIVE

The enzyme system cytochrome P450 plays a central role in the metabolism of drugs in the human body. The enzyme CYP2D6 is important for the metabolism of psychoactive agents. Genetic changes in the CYP2D6 gene can lead to reduced or absent activity.

METHODS

We report on a 37-year-old female patient who was given risperidone to treat an acute delusional disorder. Despite receiving a very low dose, the patient suffered from an intoxication. We inferred that an excessively raised plasma level of risperidone may result from a pharmacologically relevant disorder of metabolism.

RESULTS

The molecular genetic investigation revealed a compound heterozygous mutation in the CYP2D6 gene and thus documented a genetic predisposition as a "poor [non]metabolizer".

CONCLUSIONS

In intoxications with psychoactive agents, the presence of an enzyme defect in the P450 system should be considered as an additional possible cause.