Background Olanzapine is an atypical antipsychotic. Available in France since 2010, olanzapine pamoate (OP) is a prolonged-release suspension for intramuscular (IM) injection. OP is effective in the treatment of schizophrenic patients previously stabilised by oral olanzapine, and has been developed to improve compliance in these patients. In France, the injection must be performed in a psychiatric hospital department with 3-hour monitoring due to the potential ‘post-injection syndrome’ associated with OP.
Purpose To review the use and safety of OP since it became available in our hospital in May 2011.
Materials and Methods Retrospective study conducted from June 2011 to October 2012 in our 750-bed psychiatric hospital. Analysis of dispensing of long-acting IM antipsychotics: number of patients treated by olanzapine, risperidone and haloperidol. Analysis of OP prescriptions: number of patients, dosage and dose adjustment, treatment duration. Analysis of clinical data: diagnosis, treatment initiation and disruption, post-injection monitoring (blood pressure, heart rate, conscious state) and safety (other adverse events).
Results During the study period, 511 patients were treated by long-acting IM antipsychotics: 43% by haloperidol, 53% by risperidone and 4% by OP. OP was administered to 19 schizophrenic patients, mainly not compliant. In accordance with recommendations, a monthly dose of 405 mg was prescribed initially for 4 patients, 300 mg per 2 weeks for 1 patient, maintenance dosage after 2 months for 7 patients. 4 patients had only 1 injection. 3 patients required doses adjustments. 9 treatment disruptions were recorded during the study period for several reasons: care disruption, lost to follow-up, fear of injections. For the 10 patients currently treated, average treatment duration is 8 months. Post-injection monitoring data are collected on a special report form. Monitoring is performed for all injections in clinical departments. Altered consciousness has been reported in 1 patient during the 3 hours post-injection period without blood pressure or heart rate abnormalities and with normal vigilance 3 hours later. This suspected post-injection syndrome was notified to the pharmacovigilance services. Apart from this event, OP has been well tolerated.
Conclusions OP prescription is less frequent relative to other long-acting IM antipsychotics, probably because of its recent availability, physicians’ reluctance due to the risk of post-injection syndrome and requirement for hospitalisation and monitoring in the psychiatric department. This monitoring is strictly observed and reported in our hospital using our special form. Only one mild adverse effect was reported but confirms the importance of post-injection monitoring and continuing follow-up. OP is an additional therapeutic option for schizophrenic patients with poor compliance.
No conflict of interest.
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