Study objectives: To report a classic case of normeperidine toxicity, and to present institution-specific data on meperidine usage patterns and the frequency of adverse drug reactions (ADRs).
Methods: A chart review was conducted of patients at high risk for ADRs. High-risk patients were identified through the pharmacy computer system as those with renal insufficiency (creatinine clearance < or = 50 ml/min), those receiving meperidine with patient-controlled analgesia (PCA), or those receiving more than 200 mg/day of intravenous meperidine for multiple days.
Results: Twenty-five percent of patients who received meperidine had some degree of renal insufficiency. The average daily dose of meperidine was 230 mg; cumulative doses ranged from 10-7200 mg. Adverse drug reactions documented in 20 (14%) of 141 patients were confusion, anxiety, nervousness, hallucinations, twitching, and seizure. Sixteen of the 20 patients received meperidine by PCA pump or a combination of PCA and intravenous administration. Patients with ADRs to meperidine were older (58.5 vs 46.4 yrs, p = 0.004), received more concomitant benzodiazepines (65.0% vs 4.1%, p < 0.0001), and had a longer hospital stay (median 9.5 vs 4.6 days, p < 0.001) than those who did not experience an ADR. A significant difference was found in cumulative PCA doses between patients with and without documented ADRs (median meperidine dose 863 and 455 mg, respectively, p = 0.0157). Doses were directly correlated with both renal function (p < 0.05) and length of stay (p < 0.008). Dosing, duration, and frequency of ADRs for patients using PCA differed significantly between prescribing services (p < 0.01).
Conclusion: Patients using PCA meperidine are at particularly high risk of experiencing ADRs based on cumulative doses and duration of treatment. Adverse drug reactions were documented in approximately 14% of patients. Our results warrant restriction of PCA meperidine and evaluation of meperidine usage policies to improve pain management services and decrease the frequency of ADRs.