Residue Behavior and Risk Assessment of Diazepam and Its Metabolites in Crucian Carp (Carassius auratus) After Oral Administration

Diazepam (DZP), a benzodiazepine medication, is extensively utilized in both human and veterinary medicine and has been frequently detected in fish populations. The use of DZP-laced bait is identified as a predominant contributor to drug residue contamination in fish. Nonetheless, our understanding of the residue profile of DZP in fish and its potential implications for human health remains constrained. This study investigated the residue behavior and dietary intake risks of DZP and its primary metabolites in crucian carp (Carassius auratus) following oral administration. A rapid and sensitive UHPLC-MS/MS method was developed and validated for the reliable quantification of DZP and its identified metabolites. The findings revealed rapid absorption and extensive distribution of DZP in crucian carp, with peak concentrations in plasma and tissues occurring at 1 h. The distribution pattern of DZP, based on calculated AUC, was kidney > liver > plasma > gill > muscle plus skin. The distribution of DZP in plasma and tested tissues followed the decreasing order of kidney > liver > plasma > gill > muscle plus skin according to the calculated AUC. DZP elimination was notably slow, particularly in muscle plus skin, with an elimination half-life of 619.31 h, necessitating at least 70 days for concentrations to fall below the limit of quantitation, suggesting a high likelihood of residue formation in fish from oral DZP administration. DZP was metabolized into nordiazepam and temazepam in crucian carp; nordiazepam is the main metabolite of DZP, which is gradually higher than the parent drug in the elimination phase. The dietary risk assessment suggested that a possible health risk (HQ ≥ 0.1) was found within 1 day via ingestion of crucian carp after an oral dose of DZP, suggesting that frequent consumption of high-residue crucian carp may cause harm to human health.