Pharmacokinetics of cefquinome in rainbow trout (Oncorhynchus mykiss) after intravascular, intraperitoneal, and oral administrations

Effect of body size on the oral pharmacokinetics of oxytetracycline in rainbow trout (Oncorhynchus mykiss)

Objective

The aim of this study was to determine the plasma pharmacokinetics of oxytetracycline (OTC) in rainbow trout (Oncorhynchus mykiss) of different body sizes.

Methods

The research was carried out on three groups as small (30-50 g), medium (90-110 g) and large (185-215 g) body sizes at 8 ± 0.5 °C. OTC was administered orally at a dose of 60 mg/kg to all groups. Blood samples were taken at 19 different sampling times until the 384 h after oxytetracycline administration. The plasma concentrations of OTC were measured using high pressure liquid chromatography-ultraviolet and pharmacokinetic parameters were evaluated using non-compartmental analysis.

Results

OTC was detected in small-body sized fish until the 336 h and in medium and large-body sized fish until the 384 h. The elimination half-life of OTC was 85.46, 87.24 and 86.98 h in the small, medium and large body size groups, respectively. The peak plasma concentration increased from 0.66 to 1.11 µg/mL, and the area under the plasma concentration-versus time curve from zero (0) h to infinity (∞) increased from 87.86 to 151.52 h*µg/mL, in tandem with the increase in fish body size. As fish body size increased, volume of distribution and total body clearance decreased.

Conclusion

These results show that the pharmacokinetics of OTC vary depending on fish size. Therefore, there is a need to reveal the pharmacodynamic activity of OTC in rainbow trout of different body sizes.

Pharmacokinetics, bioavailability and plasma protein binding of tolfenamic acid in rainbow trout (Oncorhynchus mykiss)

BACKGROUND

Although research on the mechanism and control of pain and inflammation in fish has increased in recent years, the use of analgesic drugs is limited due to the lack of pharmacological information about analgesic drugs. Tolfenamic acid is a non-steroidal anti-inflammatory drug and can be used in fish due to its low side effect profile and superior pharmacokinetic properties.

OBJECTIVES

The pharmacokinetics, bioavailability and plasma protein binding of tolfenamic acid were investigated following single intravascular (IV), intramuscular (IM) and oral administration of 2 mg/kg in rainbow trout at 13 ± 0.5°C.

METHODS

The experiment was carried out on a total of 234 rainbow trout (Oncorhynchus mykiss). Tolfenamic acid was administered to fish via IV, IM and oral route at a dose of 2 mg/kg. Blood samples were taken at 13 different sampling times until the 72 h after drug administration. The plasma concentrations of tolfenamic acid were quantified using high pressure liquid chromatography-ultraviolet (UV) and pharmacokinetic parameters were assessed using non-compartmental analysis.

RESULTS

The elimination half-life (t1/2ʎz) of tolfenamic acid for IV, IM and oral routes was 3.47, 6.75 and 9.19 h, respectively. For the IV route, the volume of distribution at a steady state and total body clearance of tolfenamic acid were 0.09 L/kg and 0.03 L/h/kg, respectively. The peak plasma concentration and bioavailability for IM and oral administration were 8.82 and 1.24 µg/mL, and 78.45% and 21.48%, respectively. The mean plasma protein binding ratio of tolfenamic acid in rainbow trout was 99.48% and was not concentration dependent.

CONCLUSIONS

While IM route, which exhibits both the high plasma concentration and bioavailability, can be used in rainbow trout, oral route is not recommended due to low plasma concentration and bioavailability. However, there is a need to demonstrate the pharmacodynamic activity of tolfenamic acid in rainbow trout.

Effect of Dexketoprofen on the Disposition Kinetics of Moxifloxacin in Plasma and Lung in Male and Female Rats

BACKGROUND

The simultaneous use of NSAIDs and antibiotics is recommended for bacterial diseases in human and veterinary medicine. Moxifloxacin (MFX) and dexketoprofen (DEX) can be used simultaneously in bacterial infections. However, there are no studies on how the simultaneous use of DEX affects the pharmacokinetics of MFX in rats.

OBJECTIVES

The aim of this study was to determine the effect of DEX on plasma and lung pharmacokinetics of MFX in male and female rats.

METHODS

A total of 132 rats were randomly divided into 2 groups: MFX (n=66, 33 males/33 females) and MFX+DEX (n=66, 33 females/33 males). MFX at a dose of 20 mg/kg and DEX at a dose of 25 mg/kg were administered intraperitoneally. Plasma and lung concentrations of MFX were determined using the highperformance liquid chromatography-UV and pharmacokinetic parameters were evaluated by noncompartmental analysis.

RESULTS

Simultaneous administration of DEX increased the plasma and lung area under the curve from 0 to 8 h (AUC0-8) and peak concentration (Cmax) of MFX in rats, while it significantly decreased the total body clearance (CL/F). When female and male rats were compared, significant differences were detected in AUC0-8, Cmax, CL/F and volume of distribution. The AUC0-8lung/AUC0-8plasma ratios of MFX were calculated as 1.68 and 1.65 in female rats and 5.15 and 4.90 in male rats after single and combined use, respectively.

CONCLUSION

MFX was highly transferred to the lung tissue and this passage was remarkably higher in male rats. However, DEX administration increased the plasma concentration of MFX in both male and female rats but did not change its passage to the lung. However, there is a need for a more detailed investigation of the difference in the pharmacokinetics of MFX in male and female rats.

Pharmacokinetics, Tissue Residues, and Withdrawal Times of Oxytetracycline in Rainbow Trout (Oncorhynchus mykiss) after Single- and Multiple-Dose Oral Administration

The aim of this study was to compare the pharmacokinetics of oxytetracycline (OTC) following single- (60 mg/kg) and multiple-dose oral administrations (60 mg/kg, every 24 h for 7 days) in rainbow trout. It also aimed to determine bioavailability after a single dose and tissue residues and withdrawal times after multiple doses. This study was carried out on 420 rainbow trout at 9 ± 0.8 °C. This study was carried out in two stages: single-dose (intravascular and oral) and multiple-dose treatment. The OTC concentrations in plasma and tissues were measured by high-performance liquid chromatography and analyzed by a non-compartmental method. The withdrawal time (WT) was estimated using the WT 1.4 software. OTC exhibited a long terminal elimination half-life (t1/2ʎz) after IV and oral administration. The oral bioavailability of OTC was very low (2.80%). In multiple-dose treatment, t1/2ʎz, the area under the plasma concentration-time curve and peak plasma concentration increased significantly after the last day compared to the first day. OTC showed strong accumulation after multiple doses with a value of 5.33. OTC concentrations were obtained in the order liver > kidney > muscle+skin > plasma. At 9 ± 0.8 °C, the WT calculated for muscle+skin was 56 days for Europe and 50 days for China, respectively. The t1/2ʎz (68.94 h) and time (68 h) above the 1 µg/mL MIC following a single OTC dose may support the extension of the 24 h dosing interval following multiple dosing. However, further studies are required to determine the optimal dosage regimen in multiple-dose OTC treatment in the treatment of infections caused by susceptible pathogens.

Effects of Temperature on the Pharmacokinetics, Tissue Residues, and Withdrawal Times of Doxycycline in Rainbow Trout (Oncorhynchus mykiss) following Oral Administration

The purpose of this study was to compare the pharmacokinetics, tissue residues, and withdrawal times of doxycycline after oral administration in rainbow trout reared at 10 and 17 °C. Fish received a 20 mg/kg oral dose of doxycycline after a single or 5-day administration. Six rainbow trout were used at each sampling time point for plasma and tissue samples, including liver, kidney, and muscle and skin. The doxycycline concentration in the samples was determined using high-performance liquid chromatography with ultraviolet detector. The pharmacokinetic data were evaluated by non-compartmental kinetic analysis. The WT 1.4 software program was used to estimate the withdrawal times. The increase of temperature from 10 to 17 °C shortened the elimination half-life from 41.72 to 28.87 h, increased the area under the concentration-time curve from 173.23 to 240.96 h * μg/mL, and increased the peak plasma concentration from 3.48 to 5.50 μg/mL. At 10 and 17 °C, the doxycycline concentration was obtained in liver > kidney > plasma > muscle and skin. According to the MRL values stated for muscle and skin in Europe and China (100 μg/kg) and in Japan (50 μg/kg), the withdrawal times of doxycycline at 10 and 17 °C were 35 and 31 days, respectively, for Europe and China and 43 and 35 days, respectively, for Japan. Since temperature significantly affected pharmacokinetic behavior and withdrawal times of doxycycline in rainbow trout, temperature-dependent dosing regimens and withdrawal times of doxycycline might be necessary.

Plasma and muscle tissue disposition of enrofloxacin in Nile tilapia (Oreochromis niloticus) after intravascular, intraperitoneal, and oral administrations

The aim of the study was to investigate the plasma and muscle pharmacokinetic of enrofloxacin (ENR) and its active metabolite ciprofloxacin (CIP) in Nile tilapia (Oreochromis niloticus) following single intravascular (IV), intraperitoneal (IP), or oral (PO) administration at 30 ± 1 °C. In this study, 234 healthy Nile tilapia (120-150 g) were used. The fish received a single IV, IP, or PO treatment of ENR at a dose of 10 mg/kg. The plasma and muscle tissue concentrations of ENR and CIP were measured using high-performance liquid chromatography with fluorescence detection and were evaluated using non-compartmental analysis. The elimination half-life, volume of distribution at steady state, and total body clearance of ENR were 21.7 h, 2.69 L/kg, and 0.09 L/h/kg, respectively. The peak plasma concentrations of ENR after IP or PO administration were 6.11 and 4.21 µg/mL at 0.25 and 2 h, respectively. The bioavailability of ENR for IP or PO routes was 78% and 86%, respectively. AUC_{(0-120)muscle}/AUC_{(0-120)plasma} ratios following the IV, IP, or PO administrations were 1.43, 1.49, and 1.07, respectively. CIP was detected after all routes, but the AUC_0-last ratios of CIP to ENR were <1.0% for plasma and muscle. ENR was detected up to 120 h following the IV, IP, or PO administrations. The long residence time of ENR after single IV, IP, or PO administration ensured the plasma concentration was ≥1 × MIC for bacteria with threshold MIC values of 0.92, 0.72, and 0.80 μg/mL over the whole 120 h observed. However, further studies are necessary to determine the optimum pharmacokinetic/pharmacodynamics data of ENR for the treatment of infections caused by susceptible bacteria in tilapia.