Subcutaneous and intramuscular injection of oxytetracycline in calves: comparison of serum concentration and local tolerance

Plasma Creatine Kinase and Aspartate Aminotransferase Activities Before, During, and After 5 Days of Intramuscular Penicillin Administration in Sedentary Horses

Muscle damage can result in leakage of intracellular enzymes such as creatine kinase (CK) and aspartate transaminase (AST) into plasma. There are no controlled documentations of the effects of intramuscular antibiotic drug administration on plasma CK and AST activities in horses. The objective of this experiment was to test the hypothesis that 5 days of intramuscular procaine penicillin G injection in normal horses would result in increased plasma activities of CK and AST. Nine healthy adult horses were sampled for 7 days preceding, 5 days during, and 32 days following procaine penicillin G (22,000 IU/kg) administration intramuscularly twice daily. Heparinized jugular venous blood samples were obtained daily before treatment and were analyzed the same day for plasma activities of CK and AST. Repeated measures ANOVA and post hoc Tukey's Test were used to identify days where CK or AST were elevated compared to control means at a significance level of P < .05. Beginning the day after first injection, plasma CK increased above the reference range, peaking at 2,046 ± 627 U/L after 3 days, and returned to 227 ± 57.3 U/L (within the reference range) 9 days after treatment began. Beginning the day after first injection, plasma AST increased, peaking at 703 ± 135 U/L on the day after the last injection. Plasma AST did not return to the reference range in all individual horses until 29 days after the last injection (mean 247 ± 33 U/L). Compared to the control period, plasma CK and AST elevations lasted for 8 and 28 days, respectively, after the onset of treatment (P < .001 to P = .03) and lasted for 4 and 24 days, respectively, after the last day of treatment (P < .001 to P = .03).

Modelling Shows the Negative Impact of Age Dependent Pharmacokinetics on the Efficacy of Oxytetracycline in Young Steers

The effect of age dependent pharmacokinetics (PK) on the clinical efficacy of oxytetracycline (OTC) against Bovine Respiratory Disease (BRD) in beef cattle was studied, using a Physiologically Based Pharmacokinetic (PBPK) model. The model includes a bodyweight dependent renal clearance. To mimic/reproduce the long terminal half-live a bone forming tissue compartment was considered. Data for the development, calibration and validation of the model were obtained from public literature. To integrate the PK with the pharmacodynamics (PD) of OTC, Monte Carlo simulations were performed using this PBPK model to predict time-concentration curves for two commonly used dosing regimens of short-acting and long-acting injectable OTC formulations in virtual populations of 5,000 steer calves of 100 kg and 400 kg. These curves were then used to calculate the value of the PKPD index for OTC, which is the ratio of the area under the concentration-time curve for 24 h (AUC_24h) over the minimum inhibitory concentration (MIC) of the target pathogen (AUC_24h/MIC). The MIC values were for Mannheimia haemolytica, the dose-limiting pathogen for BRD. This integration of PBPK and PD for OTC used for the treatment of BRD in calves indicated that the Probability of Target Attainment (PTA) was sufficient for efficacy in calves of 400 kg, but insufficient for calves of 100 kg, when using a long acting dosing regimen of 20 mg/kg BW, twice, with a 48-h interval. The use of a dosing regimen of 10 mg/kg BW/day for 4 days predicted sufficient PTAs in both age groups.

Evaluation of cytologic and biochemical variables in blood, plasma, and peritoneal fluid from calves before and after umbilical herniorrhaphy

OBJECTIVE

To establish reference intervals for cytologic and biochemical variables in peritoneal fluid, whole blood, and plasma in calves with congenital umbilical hernias (CUHs) before and after herniorrhaphy and to assess whether those variables in calves with CUHs were altered, compared with findings in clinically normal calves.

ANIMALS

20 Holstein calves with or without a CUH. Procedures-10 calves with CUHs underwent herniorrhaphy. Blood and peritoneal fluid samples from all 20 calves were collected for cytologic and biochemical analyses on days 0 (before surgery), 1, 3, 5, 7, and 15. Data from the 2 groups were compared.

RESULTS

Reference intervals for the variables of interest were established for each group. Before surgery, calves with CUHs had significantly greater plasma total protein concentration and creatine kinase (CK) and aspartate aminotransferase activities and peritoneal fluid specific gravity values, compared with values for calves without CUHs. At various time points after surgery, peritoneal fluid total protein concentration; fibrinogen concentration; nucleated cell, polymorphonuclear cell, and lymphocyte counts; specific gravity; and lactate dehydrogenase, aspartate aminotransferase, and CK activities in calves with CUHs were significantly different from values in calves without CUHs. Some plasma and blood variables (eg, total protein concentration, neutrophil count, and CK activity) were significantly different between the 2 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Values of certain cytologic and biochemical variables in peritoneal fluid, blood, and plasma were different between calves with and without CUHs. Thus, determination of reference intervals for these variables is important for interpreting diagnostic test results in calves with CUHs.

Enhanced synchronous spectrofluorometric determination of tetracycline in blood serum by chemometric analysis. Comparison of partial least-squares and hybrid linear analysis calibrations

Tetracycline has been determined in human serum samples by a combination of: (1) synchronous fluorescence spectra of whole sera treated with Mg2+, and (2) the multivariate calibration methods of partial least-squares (PLS-1) and a variant of the recently introduced hybrid linear analysis (HLA), which does not require the knowledge of pure-component spectra. The calibration set was designed with 50 sera spiked with concentrations of tetracycline in the range 0.0-4.0 micrograms mL-1'. Studies concerning validation, precision, accuracy and figures of merit (selectivity, sensitivity and limit of determination) were also carried out. A novel wavelength-selection procedure was applied to minimize the effect of nonmodeled interferents present in serum samples containing bilirubin, triglycerides, and salicylate. Overall, the performance of the newly developed HLA approach seems to be better than that of PLS-1.

Pharmacokinetics of oxytetracycline after intramuscular administration with lidocaine in sheep, comparison with a conventional formulation

The pharmacokinetic behaviour of oxytetracycline (OTC) was studied in 11 sheep after intravenous and intramuscular administration at a single dosage of 20 mg kg(-1) bodyweight. A conventional formulation was injected by the intravenous route and two different preparations were administered by the intramuscular route: a conventional formulation (T-100) and an aqueous solution of OTC with lidocaine (1 per cent) (OTC-L). The objective was to determine whether there are differences between both formulations in the disposition kinetics of OTC after intramuscular administration to sheep. After intravenous administration of the conventional formulation, plasma oxytetracycline concentrations were best fitted to an open two-compartment model. Mean apparent volume of distribution was 0.77+/-0.02 litre kg(-1) and the harmonic mean half-life was three hours. The OTC transfer process between central and peripheral compartments was fast and that did not influence the elimination process. After intramuscular administrations of both formulations, half-lives were longer than after intravenous administration (mean values of 14.1 and 58.2 hours for T-100 and OTC-L respectively). In both cases, a biphasic absorption, a 'flip-flop' model and a complete bioavailability were found. OTC-L provided therapeutic plasma concentrations over 0.5 microg ml(-1) (the minimum inhibitory concentration for most susceptible pathogens) for a longer period of time than T-100 (72 hours compared with 36 or 48 hours).

Influence of injection site on the absorption of benzylpenicillin sodium in the dromedary

Benzylpenicillin absorption was compared in four dromedaries following injection subcutaneously and at three different intramuscular sites (neck, semitendinous and gluteal muscles). The rate of absorption (t1/2ab and Tmax) was slower after subcutaneous compared to intramuscular injection, but the extent of absorption (AUC) was similar for both routes of administration. Following intramuscular injection, the data suggest that the extent of absorption was highest from the semitendinous site and lowest in the neck site. These results were discussed and compared to those reported in other species.

Pharmacokinetics of chloramphenicol in sheep after intravenous, intramuscular and subcutaneous administration

The pharmacokinetics of chloramphenicol were studied in sheep after 3 single intravenous (IV), intramuscular (IM) and subcutaneous (SC) administrations (30 mg/kg). The two extravascular routes were studied during a crossover trial for a bioequivalence test. After IV and SC administrations, the plasma-concentration time graphs were characteristic of a two-compartment model, and after IM administration it was characteristic of a monocompartment model. The two routes of absorption were not bioequivalent. Using the kinetic values, multidose regimens to maintain the therapeutic chloramphenicol blood level (5 micrograms/ml) were proposed: 60 mg/kg every 12 hours for 72 hours for the IM administration and 45 mg/kg administered subcutaneously according to the same regimen. A study of the chloramphenicol residues in tissues was carried out. Chloramphenicol residues remained at the injection site, and 400 hours would be necessary to obtain the level of 10 micrograms/kg. Determination of the creatinine phosphokinase serum values showed that the subcutaneous route induced less damage to muscle than the intramuscular route.

Perioperative antimicrobial considerations for gastrointestinal surgery of cattle

Perioperative use of antimicrobial drugs constitutes extra-label use of those drugs. Principles of therapeutic and prophylactic use of antimicrobial drugs can guide decisions about their perioperative use. Regimens currently suggested are based on those principles, theoretical information, pharmacokinetic and pharmacodynamic data, extrapolation from studies with other species, empirical data, personal bias, and experience. Controlled clinical investigations are necessary to provide objective data from which specific recommendations can be derived.

Chloramphenicol and oxytetracycline residues in milk and tissues from cows and bullocks treated with an injectable formulation

A commercial formulation of chloramphenicol and oxytetracycline was administered to dairy cows and bullocks by the intramuscular route. Concentrations of drugs were determined in milk and edible tissues by high-performance liquid chromatographic and microbiological methods. The data allowed the calculation of withdrawal times for milk (4 and 17 milkings for chloramphenicol and oxytetracycline, respectively) and for tissues (35 days for chloramphenicol, more than 35 days for oxytetracycline, depending on the levels at the injection sites). Hence oxytetracycline residues were the most persistent in these types of foods, according to our dosage scheme.