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  • Author or Editor: Guillaume P. Chanoit x
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Abstract

Objective—To study the hemodynamic effects of marbofloxacin (MBF) in isoflurane-anesthetized dogs.

Animals—6 healthy 8-month-old Beagles.

Procedure—Anesthesia was induced with sodium thiopental and maintained with isoflurane. Cardiovascular variables were monitored throughout anesthesia. Marbofloxacin was administered by an IV bolus at 2 mg/kg, followed 10 minutes later by an infusion at a rate of 40 mg/kg/h for 30 minutes (total dose, 20 mg/kg). Plasma MBF concentrations were measured by high-performance liquid chromatography.

Results—The mean peak concentration during MBF infusion was 34.2 ± 6.4 µg/mL. The IV administration of the MBF bolus did not alter any cardiovascular variable in isoflurane-anesthetized dogs. Significant changes were found during infusion when a cumulative dose of 12 mg/kg had been given. The maximal decreases observed at the end of the infusion were 16% in heart rate, 26% in systolic left ventricular pressure, 33% in systolic aortic pressure, 38% in diastolic aortic pressure, 29% in cardiac output, and 12% in QT interval. All dogs recovered rapidly from anesthesia at the end of the experiment.

Conclusions and Clinical Relevance—MBF may safely be used at 2 mg/kg IV in isoflurane-anesthetized dogs, and significant adverse cardiovascular effects are found only when 6 to 8 times the recommended dose is given. (Am J Vet Res 2005;66:2090–2094)

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in American Journal of Veterinary Research

Abstract

Objective—To assess the effects of moderate exercise on plasma creatine kinase (CK) pharmacokinetics and to estimate exercise-induced muscle damage in dogs.

Animals—6 untrained adult Beagles.

Procedure—The study was divided into 3 phases. In phase 1, dogs ran for 1 hour at a speed of 9 km/h, and samples were used to determine the area under the plasma CK activity versus time curve (AUC) induced by exercise. In phases 2 and 3, pharmacokinetics of CK were calculated in dogs during exercise and at rest, respectively. Values for AUC and plasma clearance (Cl) were used to estimate muscle damage.

Results—At rest, values for Cl, steady-state volume of distribution (Vdss), and mean retention time (MRT) were 0.32 ± 0.02 ml/kg of body weight/min, 57 ± 17.3 ml/kg, and 3.0 ± 0.57 h, respectively. During exercise, Cl decreased significantly (0.26 ± 0.03 ml/kg/min), MRT increased significantly, (4.4 ± 0.97 h), and Vdss remained unchanged. Peak of plasma CK activity (151 ± 58.8 U/L) was observed 3 hours after completion of exercise. Estimated equivalent amount of muscle corresponding to the quantity of CK released was 41 ± 29.3 mg/kg.

Conclusion and Clinical Relevance—These results revealed that exercise had a minor effect on CK disposition and that the equivalent amount of muscle damaged by moderate exercise was negligible. This study illustrates the relevance for use of the minimally invasive and quantitative pharmacokinetic approach when estimating muscle damage. (Am J Vet Res 2001;62:1375–1380)

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in American Journal of Veterinary Research

Abstract

Objectives—To investigate and validate noninvasive methods for the quantitative evaluation of postinjection muscle damage.

Animals—5 adult sheep.

Procedures—Muscle lesions were induced twice in the lumbar region of the longissimus dorsi muscles (2 sides) by IM administration of a 20% formulation of long-acting oxytetracycline (20 mg/kg of body weight). Clinical signs and local cutaneous temperature above the injection site were recorded. Muscle lesions were quantitatively evaluated by ultrasonography and by use of pharmacokinetic analysis of plasma creatine kinase activity, and both were compared with a comprehensive planimetric computer-assisted analysis of the injection sites after euthanasia.

Results—Transient cutaneous hypothermia (temperature change, –3.9 ± 0.62 C) and subsequent persistent hyperthermia (3.1 ± 1.35 C) were observed after the administrations. Despite coefficient of variation < 10% for precision of ultrasonographic measurement of normal muscle, measurements of the lesions, with coefficient of variation > 60% for precision, were systematically underestimated. Quantitative evaluation of muscle damage by use of pharmacokinetic analysis of creatine kinase (12.1 ± 4.96 g) was in agreement with results of macroscopic planimetric evaluation (10.8 ± 3.64 g).

Conclusions and Clinical Relevance—Ultrasonography cannot be used for quantitative assessment of postinjection muscle damage. Pharmacokinetic analysis of creatine kinase provides an accurate quantitative evaluation of macroscopic muscle damage after IM administration of drugs. (Am J Vet Res 2001;62:1698–1705)

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in American Journal of Veterinary Research