Pharmacokinetics of N-acetyl-l-cysteine in chickens.

N-acetyl-l-cysteine (NAC) has been suggested as an antioxidant that can alleviate the negative effects of stress conditions in broilers. However, knowledge of its pharmacokinetics (PK) in this avian species is very limited. Therefore, the study aimed to shed more light on the PK properties of NAC in chickens. Broilers were subjected to single intravenous (i.v.) or oral (p.o.) treatment or multiple NAC administrations via the feed. Drug concentrations were determined by LC-MS/MS, and the data were subjected to non-compartmental analysis and modeled by non-linear mixed effect approach. NAC was eliminated in a short time after i.v. treatment, with a t1/2el of 0.93 (0.59-2.09) h. It showed limited distribution with population mean of volumes of distribution in the central and peripheral compartments V1 of 0.148 L/kg and V2 of 0.199 L/kg, respectively, and Vdarea of 0.39 (0.258-0.635) L/kg. The value of MRT was 1.76 h (range of 0.96-2.69, p < .05) after single p.o. treatment, indicating a twofold increase if compared to i.v. administration (0.87 h, 0.55-1.78). Both methods of Pk analysis revealed very limited bioavailability, <10%. Feeding behavior led to a later achievement of lower maximum plasma concentrations (5.74, range of 3.44-9.32 µg/mL, p < .05), which were maintained during the 5 days of treatment.

LC-MS/MS determination of N-acetyl-l-cysteine in chicken plasma.

N-acetyl-l-cysteine (NAC) shows beneficial effects in cases of aflatoxicosis and heat stress in poultry but little is known about its pharmacokinetics in chickens. Therefore, the study aimed to develop and validate a sensitive LC-MS/MS analytical method for quantitative analysis of NAC in chicken plasma. A split calibration curve approach was used for determination of NAC in chicken plasma. Standard curves for low (0.05-2.5 µg/ml) and high (2.5-100 µg/ml) ranges of concentrations were prepared. The standard curves for low (r2 = 0.9987) and high (r2 = 0.9899) concentrations were linear within the tested range. The limits of detection (LOD) and of quantification (LOQ) for the standard at low concentrations were 0.093 and 0.28 µg/ml, respectively. The accuracy was from 97.35 to 101.33%. The values of LOD and LOQ for the standard at high concentrations were 0.76 and 2.30 µg/ml, respectively. The accuracy was between 99.77 and 112.14%. The intra- and inter-day precisions for all concentrations from both standards did not exceed 8.57% and 10.69%, respectively. The recovery for all concentrations was between 92.45 and 105.52%. The validated method for determination of NAC in chicken plasma can be applied in future pharmacokinetic studies in chickens without dilution of samples and their repeated analysis.

Effect of N-Acetyl-L-cysteine on Activity of Doxycycline against Biofilm-Forming Bacterial Strains.

Biofilm-forming bacteria are associated with difficult-to-cure bacterial infections in veterinary patients. According to previous studies, N-acetyl-L-cysteine (NAC) showed an inhibitory effect on biofilm formation when it was applied in combination with beta-lactam antibiotics and fluoroquinolones. The lack of information about the effect of NAC on doxycycline activity against biofilm-forming strains was the reason for conducting this study. Staphylococcus aureus (S. aureus) ATCC 25923, Staphylococcus aureus O74, Escherichia coli (E. coli) ATCC 25922 and Pseudomonas aeruginosa (P. aeruginosa) ATCC 27853 were used to evaluate the activity of doxycycline with and without addition of NAC on planktonic bacteria and on biofilm formation. The minimum inhibitory concentrations (MICs) of doxycycline were not affected by NAC for Gram-negative strains and were found to be two times higher for the strains of S. aureus. The minimum biofilm inhibitory concentrations (MBICs) for Gram-negative bacteria (2 µg/mL for E. coli ATCC 25922 and 32 µg/mL for P. aeruginosa ATCC 27853), determined using a standard safranin colorimetric assay, were higher than the MICs (0.5 and 4 µg/mL, respectively). The data suggest that the combinations of doxycycline and NAC could stimulate the growth of planktonic cells of S. aureus and biofilm-forming E. coli ATCC 25922. NAC did not affect the strong inhibitory effect of doxycycline on the biofilm formation by the strains of S. aureus.

Diet restriction alone improves glucose tolerance and insulin sensitivity than its coadministration with krill or fish oil in a rabbit model of castration-induced obesity.

This study investigated the effect of 50% diet restriction and its coadministration with krill oil (KO) or fish oil (FO) on glucose tolerance and insulin sensitivity in a rabbit model of obesity. Castrated male rabbits were 50% restricted fed and supplemented with KO or FO (600 mg omega-3 polyunsaturated fatty acids/daily) for 2 months. Simultaneously, two control groups were used: castrated, full-diet-fed and castrated, 50% restricted fed rabbits without additives restricted group (RG). The energy-restricted diet decreased final body weight in castrated male rabbits and improved most insulin sensitivity and ß-cell function indexes. Combining the same diet and KO or FO, further reduced fasting blood glucose levels. However, this feed regime significantly accelerated insulin secretion and reduced gene expression of insulin receptor substrate-1, pyruvate kinase and 3-hydroxy-3-methylglutaryl-CoA synthase 2. This was manifested by reduced dynamic insulin sensitivity, assessment homoeostasis-ß-cell function indices and increased glucose elimination rate to levels comparable to or above the obese animals. Aspartate and alanine aminotransferases enzyme activities were raised more than those in the obese group. Surprisingly, KO and FO administration downregulated acetyl-coenzyme A oxidase and carnitine palmitoyltransferase 2 messenger RNA gene expression compared to the RG. In conclusion, we can assume that a better effect on insulin sensitivity and glucose tolerance was observed in the diet restriction alone than in the coadministration of KO or FO when animals are exposed to highly obesity predisposing factors. These effects could be at least in part ascribed to the modified gene expression levels of some critical enzymes and factors involved in liver glucose metabolism and ß-oxidation.