Pharmacokinetics and tissue distribution of enrofloxacin after single intramuscular injection in Pacific white shrimp

Metabolism and residue differences of Enrofloxacin between the brain and peripheral tissues and the resulting brain damages in crucian carp (Carassius auratus var. Pengze)

This study aimed to explore the metabolism and residue differences of Enrofloxacin (ENR) at two doses between the brain and peripheral tissues (liver, kidney, and muscle) along with the brain damages caused by ENR in crucian carp (Carassius auratus var. Pengze). The concentrations of ENR in tissues were determined using a validated high-performance liquid chromatography (HPLC) analysis. Relying on the hematoxylin-eosin (HE) staining method, brain damages caused by the drug were evaluated by the section of pathological tissue. Metabolism and residue results showed that ENR could be detected in the brain throughout the experiment both at median lethal dose (LD₅₀ at 96 h, 1949.84 mg/kg) and safe dose (SD, 194.98 mg/kg), as well as in the three peripheral tissues. The maximum residue at LD₅₀ followed the decreasing order of liver >kidney > brain > muscle. Although the C_max of ENR at SD in the brain was significantly lower than that in other peripheral tissues (p < .05), it still reached 41.91 μg/g. The T_1/2 of ENR in brain tissue at the same dose was both shorter than that in peripheral tissues. At LD₅₀ , the amount of ENR residues in brain was lower than that in peripheral tissues on the whole, except that it had been higher than in the muscle for the first 3 h. At SD, the drug residue in brain tissue was lower than that in peripheral tissues from 12 h to 960 h, but it exceeded the muscle and kidney at 1 h and 6 h, respectively. At 960 h, the residual amount of ENR at SD in the brain was 0.09 μg/g, while it was up to 0.15 μg/g following the oral administration at LD₅₀ . Demonstrated by the HE staining, there were pathological lesions caused by ENR in the brain at LD₅₀ , which were characterized by sparse neural network and increased staining of glial cells. The present results indicated that metabolism and residue of ENR in crucian carp were affected by the tissue type and drug dosage, and the ENR could also bring about histopathological changes in the brain.

Residue, biotransformation, risk assessment and withdrawal time of enrofloxacin in red swamp crayfish (Procambarus clarkii)

Crayfish is a very popular aquatic food in many countries, and enrofloxacin (ENR) and ciprofloxacin (CIP) was the most frequently detected in aquatic products. However, limited information is available on the residue characterization, biotransformation rate and withdrawal period (WT) of ENR and CIP in crayfish and health risk via consumption of ENR and CIP remained crayfish. Herein, a comprehensive investigation was conducted to study residue depletion, biotransformation, ingestion risk, and WT of ENR and its predominate metabolite CIP in crayfish following different routes with repeated doses. The results showed that the elimination half-life (T_1/2) of target compounds in crayfish were all in order of hepatopancreas > muscle > gill, and the order of T_1/2 in different crayfish tissues were intramuscular (IM) route > oral (PO) treatment > immersion (IMMR) administration. The biotransformation rates from ENR to CIP varied from 0.75% to 3.45% in crayfish tissues following different exposure routes. The high dietary risk (RQ > 1) consuming muscle and hepatopancreas of ENR and CIP remained crayfish occurred at early after different administrations. WT is the key to control the drug residue risk, and the longest WT of marker residue of ENR in crayfish was calculated to be 51 d (1275 °C-day).

Pharmacokinetics studies of eugenol in Pacific white shrimp (Litopenaeus vannamei) after immersion bath

Background

Eugenol is the most commonly used plant anesthetic to relieve the stressors during various aquaculture procedures. This study aims to investigate the pharmacokinetics of eugenol in Pacific white shrimp by immersion baths in a simulated transportation.

Results

The pharmacokinetics of eugenol were firstly investigated in Pacific white shrimp by immersion baths of 300 mg L^− 1 eugenol over 5 min (Treatment 1), 10 mg L^− 1 eugenol during 24 h (Treatment 2) and a sequential immersion administration (Treatment 3). Concentrations of eugenol in hemolymph, hepatopancreas, and muscle were determined using Gas chromatography-tandem mass spectrometry (GC-MS/MS). After immersion bath of Treatment 1, the elimination half-life (t_1/2z) values are 1.3 h and 11 h for hepatopancreas and muscles, indicating the rapid absorption and elimination of eugenol in shrimp. Under the Treatment 2 administration, the eugenol peak concentration is 6527.9 μg/kg in muscle, followed by 402.8 μg/kg in hepatopancreas, with the lowest concentration of 37.9 μg/L in hemolymph. Area under the curve (AUC_0-∞) values lie in the order of muscle > hepatopancreas > hemolymph, suggesting that eugenol tends to accumulate in muscle by the immersion administration. Moreover, the average residence time (MRT_0-∞) values of 38.6, 23.0 and 115.3 h for hemolymph, hepatopancreas and muscle are achieved, which may indicate that hepatopancreas is the main organ for elimination of eugenol. After combining the conditions in a sequential bath immersion of eugenol (Treatment 3), the maximum concentration (C_max) values of eugenol are higher than those achieved in Treatment 2, indicating that accumulation of eugenol happened in haemolymph, hepatopancreas and muscle. In addition, the corresponding t_1/2z values are 4.7, 14.9 and 47.6 h, respectively, suggesting the faster elimination from the tissues following sequential administration. After the immersion bath, eugenol concentrations in muscle of Pacific white shrimp are lower than 2.5 mg/kg at 2 h, 48 h and 24.5 h in Treatment 1 ~ 3.

Conclusions

A withdrawal period of 2 h, 48 h and 24.5 h following a 300 mg L^− 1 of eugenol over a 5-min, 10 mg L^− 1 eugenol concentration during a 24-h and combined conditions in a sequential immersion bath were suggested.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03145-3.

Could the gut microbiota community in the coral trout Plectropomus leopardus (Lacepède, 1802) be affected by antibiotic bath administration?

Gut microbiota in fish plays an important role in the nutrient digestion, immune responses and disease resistance. To understand the effect of fluoroquinolone antibiotic bath administration on fish gut microbiota, the gut microbiota community in the coral trout Plectropomus leopardus (Lacepède, 1802) was studied after enrofloxacin bathing treatment at two concentrations (5 and 10 mg/L) and 0 mg/L as control. A total of 90 fish were used in this study, and three replicates were used for each treatment. After a 24‐hr bath, the gut bacterial composition was analyzed using high‐throughput Illumina sequencing. The results indicated that the richness, diversity and the dominant bacterial taxa of P. leopardus gut bacteria were not affected by enrofloxacin bathing (p > .05). Proteobacteria and Firmicutes were the dominant phyla, and Exiguobacterium, Citrobacter, Vibrio, Acinetobacter, Pseudomonas were the dominant genus. The findings in the present study provide an understanding on the relationship between fish gut bacteria community and antibiotic bath administration. The findings of this study are instructive on the antibiotic bath administration applied for the management of P. leopardus health in aquaculture.

Pharmacokinetics and tissue disposition of enrofloxacin in rainbow trout after different routes of administration

Plasma pharmacokinetics (PK) and tissue disposition of enrofloxacin (EFX) was studied in rainbow trout (Oncorhynchus mykiss) after a single oral administration of 10 mg/kg, and by immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, at water temperature of 16.3 ± 0.3 °C.Concentrations of EFX in plasma and tissues (skin, muscle, liver, kidney and gut) were determined using high performance liquid chromatography (HPLC) with fluorescence detection.Pharmacokinetic parameters were analyzed with a non-compartmental model. After oral administration, t½β, AUC and AUC_tissues/AUC_plasma ratio were 42.98 h, 21.80μg-h/ml and ≤ 18.63, respectively.After immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, the t½β, AUC and AUC_tissues/AUC_plasma were 42.77 and 44.67, 9.83 and 12.83 μg-h/ml and ≤ 9.81 and ≤ 7.13, respectively.Therefore, oral (10 mg/kg) and bath administration in rainbow trout can provide AUC/MIC of ≥125 and Cmax/MIC of ≥10 to treat diseases caused by susceptible bacteria with MIC ≤ 0.04 μg/ml. This information can be helpful for the right use of EFX in rainbow trout. Also, this is the first study that determines the antibiotic tissue disposition in rainbow trout by using different administration routes.