Effectiveness and Adverse Events of Generic and Original Imipenem/Cilastatin in Hospitalized Patients: The First Multicenter Non-Inferiority Study in Thailand

Objective: Imipenem/cilastatin, a broad-spectrum antibacterial, is reserved for treatment of serious infections caused by multidrug-resistant Gram-negative bacteria. The present study was aimed to compare the effectiveness and adverse events of generic and original imipenem/cilastatin. Materials and Methods:A retrospective, multicenter, cohort, non-inferiority study of generic imipenem/cilastatin (Sianem®), and original imipenem/cilastatin (Tienam®) was carried on between November 2017 and September 2020. The centers included Srinagarind Hospital, Taksin Hospital, Nakornping Hospital, Nakhonpathom Hospital, and King Chulalongkorn Memorial Hospital. The clinically relevant data were retrieved from the medical records on day 3, 7, and 14 after enrollment. A sample size of 260 patients per arm was needed. Results: There were 214 and 227 medical and surgical patients enrolled in generic and original imipenem/cilastatin groups, respectively. Baseline characteristics of the two groups were not significantly different. Most patients were male and elderly. Comorbidity was observed in 86.6%. The average length of hospital stay was 17 days. At day 14 after enrollment, the favorable outcome in generic and original imipenem/cilastatin groups were 83.1% and 90.0%, respectively, with no statistical difference. The mortality rates were 3.4% and 2.0% in generic and original imipenem/ cilastatin groups, respectively, with no statistic difference. Serious adverse events were also not significantly different between the two groups at 0.9% and 0.4%. Conclusion: The generic imipenem/cilastatin was non-inferior to the original imipenem/cilastatin in terms of effectiveness and adverse events for the treatment of serious bacterial infections in hospitalized adult patients. Keywords: Effectiveness; Safety; Adverse events; Generic drug; Imipenem/cilastatin