Development of radioactive tracing coupled with LC/MS-IT-TOF methodology for the discovery and identification of diaveridine metabolites in pigs

Metabolism and Tissue Elimination of Diaveridine in Swine, Chickens, and Rats Using Radioactive Tracing Coupled with LC-ESI-IT-TOF/MS

Diaveridine (DVD) has widespread use in food animals due to its antibacterial synergistic effects. This study revealed the metabolism, excretion, and tissue elimination of DVD in swine, chickens, and rats following oral gavage of 10 mg/kg b.w. tritium-labeled DVD using radioactive tracing coupled with liquid chromatography-electron spray ionization-ion trap-time-of-flight-mass spectrometry (LC-ESI-IT-TOF/MS). The metabolic pathways involved demethylation, α-hydroxylation, glucuronidation, and sulfonylation and produced four metabolites in swine (M0, DVD; M1, 3'/4'-demethyl-DVD; M2, 3'/4'-demethyl-DVD-O-glucuronide; M4, 2/4-glucuronidated-DVD) and five in chickens (M0∼M2; M3, α-hydroxy-DVD; M4) and rats (M0∼M3; M5, 3'/4'-demethyl-DVD-O-sulfation). M0 was dominant in the excreta of chicken and female and male rats, while M2 was mainly excreted in swine. Among the three species studied, M0 was the most persistent in the kidneys (t_1/2 3.15-3.89 d); therefore, M0 kidney levels are residue monitoring targets. This study enabled a thorough comprehension of the metabolism and pharmacokinetic characteristics of DVD in animals.

Rapid determination of 2,4-diaminopyrimidine residues through sample pretreatment using immunomagnetic bead purification along with HPLC-UV

To reduce matrix interference and realize simultaneous detection of multiple homologous compounds (trimethoprim (TMP), diaveridine (DVD), ormetoprim (OMP), baquiloprim (BQP), and aditoprim (ADP) in pig, cattle, chicken, and fish muscles), an immunomagnetic bead (IMB)-based sample purification pretreatment with HPLC-UV was developed. A broad-spectrum monoclonal antibody (mAb, named 14C6) was prepared and conjugated with carboxylic-acid-functionalized magnetic nanoparticles using the active ester method to obtain IMBs for sample purification. The extraction solvent was optimized based on the extraction efficiency. Good linearity was observed for all the five analytes (10-200 μg/kg) with the LOD and LOQ of 5 and 10 μg/kg, respectively. The mean recoveries ranged from 62.5% to 76.9%, while the coefficient of variation was <12.2%. The IMB method afforded greater sample purification and enrichment than those achieved with the SPE column-based conventional method. Hence, the IMB-based sample purification is a useful tool to determine 2,4-diaminopyrimidine residues in edible animal tissues.

Metabolite Identification and Pharmacokinetic Behavior of Diaveridine in the Plasma of Pigs and Chickens Based on Radioactive Tracing Coupled With LC/MS-IT-TOF Assay

Diaveridine (DVD) is widely used for the prevention and treatment of coccidiosis and leucocytozoonosis infections in food-producing animals. To gain a better understanding of DVD metabolism and pharmacokinetics in healthy Landrace/Doric Cross castrated male pigs and both female and male Cobb 500 broiler chickens, a method involving radioactive tracing coupled with LC/MS-IT-TOF was developed for the identification and quantitation of DVD and its metabolites in pig and chicken plasma, and then was applied to investigate DVD pharmacokinetics. A simple MCX solid phase extraction procedure was adopted for sample preparation. After a single oral administration of 3H-DVD (10 mg/kg BW), three radioactive compounds (D0: DVD; D1: 3'-desmethyl-DVD; and D2: monoglucuronide of 3'-desmethyl-DVD) were identified in pig plasma, while only two radioactive compounds (D0 and D2) were identified in chicken plasma. In both species, the C max values for all detected compounds were reached at 2 h after dosing. The C max order was D2 (1.38 μg/ml) > D0 (0.49 μg/ml) > D1 (0.24 μg/ml) in pigs and D0 (1.55 μg/ml) > D2 (0.27 μg/ml) in chickens. The longer t 1/2 (elimination half-life) of D0 contributed to the slow elimination of DVD-related compounds. The t 1/2β of D0 in pigs (66.41 h) was significantly longer than that in chickens (48.30 h), but the t 1/2 of total DVD-related metabolites in pigs (42.86 h) was lower than that in chickens (56.11 h). These findings suggested that the metabolism and pharmacokinetics of DVD in pigs and chickens were significantly different, and that this would affect its effectiveness, toxicology, and food safety in these animals.