Extrapyramidal symptoms following administration of oral perphenazine 4 or 8 mg: An 11-year retrospective analysis

BACKGROUNDPerphenazine is a treatment option in postoperative nausea and vomiting (PONV) prophylaxis. Chronic administration and high dose are known to cause extrapyramidal system (EPS) dysfunction at a frequency of 8%, but the incidence of acute EPS after a single 4 or 8 mg dose is unknown. OBJECTIVEA retrospective analysis of patient medication billing data and departmental quality records was performed (January 2001 to 10 July 2012) to identify patients who experienced EPS dysfunction after oral perphenazine. DESIGNA retrospective analysis. SETTINGSurgical outpatients presenting to any one of 10 hospitals in the area of Pittsburgh, Pennsylvania, USA. PATIENTSOverall, 45 766 patients received 4 or 8 mg of perphenazine before same-day surgery. MAIN OUTCOME MEASURESEPS dysfunction was defined as acute dystonia, akathisia or pseudoparkinsonism. Records were reviewed to determine the likely number of reactions to perphenazine, the nature of these reactions and impact on patient care. RESULTSThere were four ‘likely’ cases of EPS dysfunction, and two ‘possible’ cases. Five reported events were consistent with akathisia, with the sixth being a dystonic reaction. All six patients had resolution of symptoms, with five receiving intravenous diphenhydramine for treatment. The incidence of EPS dysfunction was 1.3 events per 10 000 patients (95% confidence interval (CI) 0.4 to 3.0, based on six events). All patients who experienced reactions pre-operatively were able to proceed to surgery without complications or delay. One patient required unplanned admission and 3-h observation owing to sedation from diphenhydramine. The incidence of EPS dysfunction after oral perphenazine is low. Reactions that did occur were mild and easily treated. CONCLUSIONGiven the infrequent side effects, this single, low dose of perphenazine should be encouraged as a low-risk adjunct to any multimodal PONV prophylaxis regimen, based on the selection criteria described.