In Vitro Evaluation of the Compatibility of Meropenem and Tanreqing Under Parallel Infusion Conditions

Objective: This study evaluated the in vitro physicochemical compatibility of meropenem and Tanreqing Injection under simulated parallel infusion conditions, providing experimental evidence to address existing gaps in compatibility data under clinically relevant co-infusion conditions. Methods: To simulate clinical dosages, meropenem and Tanreqing Injection were prepared individually and in combination in 100 mL and 250 mL of 0.9% sodium chloride injection (NS). Changes in appearance, pH, osmolality, insoluble particles, drug content, and related impurities were investigated over a 0-24 h period to assess the compatibility of each preparation by using a fully validated liquid chromatography method. Result: Meropenem alone exhibited a slow degradation trend over 24 h at room temperature. For Tanreqing Injection alone, the chlorogenic acid content decreased to 80.0% in 100 mL of NS and 85.2% in 250 mL of NS within 24 h, indicating improved stability at higher dilution volumes. When meropenem was combined with Tanreqing Injection, the chlorogenic acid content exhibited an immediate and significant decrease upon mixing. By 24 h, the reduction reached 71.9% in the 100 mL NS combination group and 44.0% in the 250 mL NS combination group. Concurrently, levels of meropenem Impurity A increased significantly in both combination groups, with more pronounced changes observed in the 100 mL NS group (p < 0.05). Conclusions: The parallel co-infusion of meropenem and Tanreqing Injection results in immediate chemical incompatibility and significant active constituent degradation. To ensure therapeutic efficacy and patient safety, simultaneous admixture of these two agents is strictly contraindicated in clinical practice. When sequential administration is necessary, a larger diluent volume (e.g., 250 mL NS) is preferred for Tanreqing Injection, and infusion lines must be thoroughly flushed between administrations to prevent residual interactions.