Microscopic Evaluation of Crystallization Dynamics in 0.25% Levobupivacaine Mixed with Common Regional Anaesthesia Adjuvants: An in vitro Compatibility Study

Main Points• Sodium bicarbonate (8.4%) results in immediate, extensive crystallization when mixed with 0.25% levobupivacaine.• Dexamethasone induces time-dependent crystal formation, with crystals exceeding 10 μm within 60 minutes.• Adrenaline, magnesium sulfate, and dexmedetomidine exhibit little evidence of crystallization, indicating high physical stability.• In vitro microscopic analysis is an essential pre-clinical tool for screening drug-drug incompatibilities.