Comparing the Safety Profiles of Vaginally Administered Misoprostol and Dinoprostone: A Retrospective...

Misoprostol and dinoprostone are the most commonly used agents for cervical ripening during labour induction. However, comparative safety data remain limited, particularly regarding rare adverse events and off-label use. Data were obtained from the FDA Adverse Event Reporting System (FAERS) database for the period from the first quarter of 2004 to the fourth quarter of 2023. Adverse event (AE) reports involving vaginal administration of misoprostol and dinoprostone were extracted, followed by deduplication and exclusion of cases without a specified route of administration. A total of 3,925 misoprostol-related and 1,191 dinoprostone-related AEs were included for analysis. Clinical characteristics were then compared between the two groups. Pharmacovigilance signal detection was performed at both the system organ class (SOC) and preferred term (PT) levels using disproportionality and Bayesian approaches, including reporting odds ratios (RORs), proportional reporting ratios (PRRs), information components (ICs), and empirical Bayesian geometric means (EBGMs). Distinct safety profiles were observed between the two agents. Dinoprostone was primarily associated with pregnancy-related complications, including stronger signals for uterine rupture and postpartum haemorrhage. In contrast, misoprostol was more frequently associated with pregnancy termination-related events, including incomplete abortion, as well as gastrointestinal adverse effects such as abdominal pain. Misoprostol also demonstrated a stronger signal for off-label use. These findings suggest that vaginally administered misoprostol and dinoprostone exhibit different safety profiles, which may inform clinical decision-making during labour induction by highlighting potential risks associated with each agent. However, because FAERS is a spontaneous reporting system subject to underreporting, reporting bias, and the inability to establish causality, the results should be interpreted with caution. Further prospective studies are warranted to validate these safety observations.