Objective: In Japan, the healthcare authority encourages physicians to prescribe generic drugs in order to reduce the copayments by the patients for pharmaceutical expenses and to improve the financial status of the national medical insurance system.  In accordance with this governmental policy, we have been actively involved in switching original to generic formulations.  Thus, Utemerine® 50 mg injection was replaced with Ritodrine hydrochloride 50 mg intravenous injection produced by Nichiiko.  There have been some reports on adverse events caused by the generic formulations of Ritodrine hydrochloride.  Factors contributing to these adverse effects may include different additives and/or vehicles and the exemption of demonstrating some conditions for approval, including clinical trials.  Therefore, in order to assess the efficacy and safety of a generic formulation of Ritodrine hydrochloride injection formulation compared with the original formulation and to decide on its continued use, we carried out a retrospective cohort study.
Methods: We carried out a retrospective cohort study in order to assess the efficacy and safety of a generic formulation of Ritodrine hydrochloride injection formulation compared with the original formulation.
Results: There were no significant differences in the length of hospital stay, rate of emergency transport to other institutions, gestational week of delivery, rate of stillbirth, rate of abortion, or incidence of adverse events between the two formulations.
Conclusion: Our results may contribute to the safe and secure use of the generic formulations of Ritodrine hydrochloride in the current situation of the increasing use of generic drugs in health care.  Although there are some limitations in our study, the results suggest that there are no particular problems with the continued use of Ritodrine hydrochloride 50 mg intravenous injection produced by Nichiiko.