To the Editor: The following are reports of three male inpatients who developed extrapyramidal symptoms within 24 hours of an injection of depot risperidone. All three men met DSM-IV criteria for schizophrenia.
Mr. A, a 32-year-old man, had been taking 15 mg/day of olanzapine for the last 4 months. Because of a long history of poor adherence to treatment in the community, we prescribed a depot antipsychotic. Injectable risperidone, 25 mg, was given while Mr. A was taking 15 mg/day of olanzapine. Twenty-four hours after the injection, he developed oculogyric crisis, dysarthria, torticollis, dysphagia, tremor, and rigidity. These symptoms responded to procyclidine.
Mr. B, a 36-year-old man, was taking depot zuclopenthixol decanoate, 400 mg every 2 weeks, for 12 months. Because of extrapyramidal side effects, we decided to change the zuclopenthixol decanoate to injectable risperidone. Instead of his regular depot treatment, Mr. B received 25 mg of injectable risperidone. Twenty-four hours later, his extrapyramidal symptoms worsened. These symptoms remitted in 1 week without specific treatment.
Mr. C, a 28-year-old man, was taking olanzapine, 20 mg/day, for 4 weeks. Because of a long history of poor adherence to treatment in the community, we decided to offer depot medication. Olanzapine was reduced and finally stopped within 1 week. After that, we began treatment with oral risperidone and reached 4 mg/day in 3 days. The next day, a few hours after the injection of 25 mg of risperidone, Mr. C developed akathisia, which responded to lorazepam.
The development of extrapyramidal symptoms within 24 hours of administering the depot was not expected. Despite adherence to current guidelines on switching to long-acting injectable risperidone (1), extrapyramidal symptoms still developed in our patients within 24 hours of the depot injections. These symptoms maybe attributed to the initial release of risperidone in the bloodstream.
After a single intramuscular injection of risperidone, there is a small initial release of drug (<1% of the dose), followed by a lag time of 3 weeks when risperidone is not released. After the intramuscular injection, the main release of the drug starts at week 3 and is maintained from 4 to 6 weeks. The release of the drug begins to decrease at week 7 (2).
To limit the risk of developing extrapyramidal symptoms around the time of the injection, it may occasionally be necessary to reduce or omit the dose of the oral antipsychotic in the days after the injection. Attention should be paid to the half-life of any other depot drug given in the period before the initiation of injectable risperidone.