Higher than expected rates of seizures associated with the use of ertapenem in older hospitalized patients

BackgroundUse of carbapenems is expected to increase with rising prevalence of multidrug-resistant bacteria. Available literature indicates that the incidence of seizure with ertapenem use ranges from 0.2% to 0.5% in adults. However, anecdotal clinical experience suggests that the frequency of seizures in frail geriatric patients could be higher.AimWe sought to estimate the rate of seizures with the use of ertapenem in older hospitalized patients and to identify possible predisposing factors for their occurrence.MethodsWe performed a retrospective chart review for hospital episodes of patients who were admitted to the department of geriatric medicine of an acute care hospital and received at least one dose of ertapenem between October 2009 and September 2010.ResultsChart reviews for 116 patients were conducted. The mean age of the study population was 82.9 years [standard deviation (SD) = 8.1] and 69% of the patients were female. The mean number of comorbidities was 8.6 (SD = 3.7) and the mean number of assisted or dependent activities of daily living out of 5 was 3.5 (SD = 2.0). Seizures occurred in six (5.17%) hospitalized patients. The Naranjo Adverse Drug Reaction Probability Scale revealed a causality relationship graded as “possible” in two episodes and “probable” in the remaining four episodes. Patients who experienced seizures were significantly younger (mean age: 75.7 vs. 83.3 years, p = 0.023) and had fewer comorbidities (5.5 vs. 8.8, p = 0.033). Seizure occurrence had statistically nonsignificant associations with a history of central nervous system disorders and previous seizures.ConclusionWe found a higher rate of seizures amongst older hospitalized patients who were using ertapenem than reported in existing literature. Further studies should include a wider population of older hospitalized patients and compare seizure incidence with the use of carbapenem alternatives.