RESIDUAL TOXICITY VERSUS ARTEMIA SALINA OF EXPIRED AMIKACINS

Objetive: Amikacin is an aminoglycoside antibiotic characterized by high water solubility and environmental stability. Improper disposal of expired formulations can contribute to the spread of antibiotic resistance and disturb aquatic ecosystems. This study aimed to evaluate the residual toxicity of expired amikacin using the Artemia salina lethality bioassay. Methods: The median lethal concentration (LC₅₀) of 39 expired and 3 non-expired amikacin vials was determined using the Artemia salina bioassay. Residual amikacin concentrations were quantified via a validated ninhydrin-based spectrophotometric method. Corrected LC₅₀ (LC₅₀C) values were calculated based on the residual concentration to assess the toxicity of degradation products. Results: LC₅₀ values of expired samples ranged from approximately 100 to 600 mg/L, showing an inverse linear relationship with the residual concentration of the active ingredient (y = –0.0867x + 112.41; R² = 0.9249). LC₅₀ increased proportionally with time elapsed after expiration, indicating that toxicity decreases as amikacin degrades. When corrected for residual concentration, the adjusted LC₅₀ values (LC₅₀C) indicated that drug decomposition did not generate additional toxic compounds, as lethality corresponded to the remaining active ingredient. Conclusion: These findings highlight the importance of ecopharmacovigilance and underscore the need for proper management of expired pharmaceuticals to prevent environmental contamination.