Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: Marc Schneider x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To evaluate, by use of population pharmacokinetics, the disposition of marbofloxacin in the aqueous humor after IV administration in dogs and identify its potential usefulness in the prophylaxis and treatment of intraocular infection.

Animals—63 dogs.

Methods—Dogs received a single dose of marbofloxacin (2 mg · kg–1, IV) at various time intervals before cataract surgery. Aqueous humor and blood samples were collected at the beginning of surgery. Marbofloxacin concentrations were measured by high-pressure liquid chromatography. Data were analyzed with a nonlinear mixed-effect model and, by use of population pharmacokinetic parameters, the time course of aqueous humor concentration was simulated for single doses of 3, 4, and 5.5 mg · kg–1IV. Pharmacodynamic surrogate markers and measured aqueous humor concentrations were used to predict in vivo antimicrobial activity.

Results—A maximum marbofloxacin concentration of 0.41 ± 0.17 µg·mL–1 was reached in the aqueous humor 3.5 hours after IV administration. In the postdistributive phase, marbofloxacin disappeared from aqueous humor with a half-life of 780 minutes. The percentage penetration into the aqueous humor was 38%. Predictors of antimicrobial effects of marbofloxacin (2 mg · kg–1, IV) indicated that growth of the enterobacteriaceae and certain staphylococcal species would be inhibited in the aqueous humor. Marbofloxacin administered IV at a dose of 5.5 mg · kg–1 would be predicted to inhibit growth of Pseudomonas aeruginosa and all strains of staphylococci but would not eradicate streptococcal infections.

Conclusions and Clinical Relevance—Marbofloxacin administered IV can penetrate the aqueous humor of canine eyes and may be suitable for prophylaxis or treatment of certain anterior chamber infections. (Am J Vet Res 2003;64:889–893)

Full access
in American Journal of Veterinary Research

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)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare penetration of IV administered marbofloxacin in intraocular fluids of healthy and inflamed eyes in rabbits with endotoxin-induced endophthalmitis.

Animals—35 pigmented rabbits.

Procedures—Endophthalmitis was induced in the right eye via intravitreal administration of Escherichia coli endotoxin. The left eye was a control eye. After 24 hours, a single dose of marbofloxacin (4 mg/kg, IV) was administered. Groups of rabbits (n = 5/group) were euthanized 0.5, 1, 2, 4, 6, 10, and 18 hours later, and blood and ocular fluids were collected. Marbofloxacin concentrations were determined via reverse-phase high-performance liquid chromatography, and pharmacokinetic analysis of the data was performed with a mono-compartmental model.

Results—Mean area under the aqueous concentration-time curve was significantly lower in control eyes (1.64 ± 0.07 μg•h/mL) than in inflamed eyes (3.31 ± 0.11 μg•h/mL). Similarly, drug penetration into aqueous humor was 33% and 65% for control eyes and inflamed eyes, respectively. Mean area under the vitreous humor concentration-time curve for control eyes(1.75 ± 0.05 μg•h/mL) was significantly less than for inflamed eyes (2.39 ± 0.16 μg•h/mL). In the vitreous humor, corresponding penetrations were 34% and 47%, respectively.

Conclusions and Clinical Relevance—Penetration of marbofloxacin into the aqueous and vitreous humor after IV administration was significantly enhanced by intraocular inflammation, suggesting a role for this antimicrobial in the prophylaxis or treatment of bacterial endophthalmitis caused by susceptible pathogens.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine effect of 3 half-limb casts on bone strains recorded from the proximal phalanx (P-1) and third metacarpal bone (MCIII) of equine cadaver limbs, using a mechanical testing machine.

Animals

12 equine cadaver limbs and 4 live horses.

Procedure

Bone strains were recorded at middorsal P-1 and the dorsal cortical aspect of the distal third of MCIII while limbs were variably loaded with 100 to 1,000 lb of force. To determine ability of the cast to protect the distal portion of the limb from weight-bearing loads, strains were recorded with the limb in 1 of the 3 casts and with it unsupported. To determine cast-induced discomfort, weight-supporting and transfixation pin casts were evaluated on 2 live horses

Results

All 3 casts significantly reduced bone strain at P-1. Significant differences were observed: mean 61 % reduction for the standard half-limb cast, 84% for the transfixation pin cast, and 97% for the weight-supporting cast at weight-bearing force of 500 lb. Only the weight-supporting cast significantly reduced strains recorded from MCIII. The weight-supporting cast was not well tolerated by 2 live horses.

Conclusions

The 3 casts significantly reduced transfer of weight-bearing forces to the distal portion of the limb. The weight-supporting cast effectively reduced strain on the P-1 to near 0, but was well tolerated by live horses. The transfixation pin cast reduced strain on the P-1 by > 80% at weight-bearing loads of 500 lb, and live horses were comfortable. Standard half-limb casts significantly reduced strains on the P- 1, but to a lesser degree than did other casts. (Am J Vet Res 1998;59:1188-1193)

Free access
in American Journal of Veterinary Research

Abstract

Objective—–To compare transfixation and standard full-limb casts for prevention of in vitro displacement of a mid-diaphyseal third metacarpal osteotomy site in horses.

Sample Population—6 forelimbs from 6 horses euthanatized for reasons not related to the musculoskeletal system.

Procedure—A 30° osteotomy was performed in the mid-diaphysis of the third metacarpal bone. Two 4.5-mm cortical bone screws were placed across the osteotomy site to maintain alignment during casting. Two 6.35-mm Steinmann pins were placed from a lateral-to-medial direction in the distal aspect of the radius. A full-limb cast that incorporated the pins was applied. An extensometer was positioned in the osteotomy site through a window placed in the dorsal aspect of the cast, and after removal of the screws, displacement was recorded while the limb was axially loaded to 5,340 N (1,200 lb). Pins were removed, and the standard full-limb cast was tested in a similar fashion.

Results—The transfixation cast significantly reduced displacement across the osteotomy site at 445 N (100 lb), 1,112 N (250 lb), 2,224 N (500 lb), and 4,448 N (1,000 lb), compared with the standard cast.

Conclusion and Clinical Relevance—A full-limb transfixation cast provides significantly greater resistance than a standard full-limb cast against axial collapse of a mid-diaphyseal third metacarpal osteotomy site when the bone is placed under axial compression. Placement of full-limb transfixation casts should be considered for the management of unstable fractures of the third metacarpal bone in horses. (Am J Vet Res 2000;61:1633–1635)

Full access
in American Journal of Veterinary Research

SUMMARY

Objective

To determine the effect of pin hole size and number on the breaking strength of the adult equine radius when loaded in torsion to failure.

Sample Population

54 pairs of equine radii from adult horses.

Procedure

For test one, 12 pairs of radii were used to determine the effect of pin hole size on torsional breaking strength. A 6.35-mm hole was drilled in 1 radius, and a 9.5-mm hole was drilled in the contralateral radius. For test two, 36 pairs of radii were randomly assigned to 1 of 3 treatment groups (n = 12) to determine the effect of pin hole number on the torsional breaking strength of the equine radius. One radius of each pair served as a control, and one, three, or six 6.35-mm transcortical holes were drilled in the contralateral radius. For test three, 6 pairs of radii had torsional forces applied directly to the transfixation pins, as opposed to the bone itself. One radius of a pair served as a control, and three 6.35-mm smooth Steinman pins were placed in the contralateral radius. All radii were loaded in torsion to failure, and the breaking strengths were recorded.

Results

Compared with the 6.35-mm hole, the 9.5-mm hole significantly decreased torsional strength of the radius. There was no significant difference in mean torsional strength between the control radii and the radii with 1, 3, or 6 transcortical holes or when the transfixation pins were loaded.

Conclusion

Use of up to three 6.35-mm transfixation pins can be used in a full-limb transfixation pin cast to optimize stiffness without a significant decrease (12%) in bone strength. (Am J Vet Res 1998; 59:201–204)

Free access
in American Journal of Veterinary Research

SUMMARY

Objective

To determine the ability of a full-limb transfixation pin cast to protect the distal portion of the equine forelimb from weight-bearing forces by measuring bone strain in vitro on cadaver limbs loaded in a mechanical testing machine.

Sample Population

6 forelimbs from 6 horses.

Procedure

Each limb was instrumented with 3 unidirectional metal foil electrical resistant strain gauges. Gauges were placed on the dorsal aspect of the distal portion of the radius and the mid-dorsal portion of the cortex of the third metacarpal bone and the first phalanx. Each limb was tested 3 times, once supported with a transfixation pin cast, once supported by a standard full-limb cast, and finally, uncast. The limbs were tested in a mechanical testing machine under axial loads ranging from 100 to 1,000 lb, and bone strains were recorded at each load.

Results

Compared with values for the uncast limb, the transfixation pin cast and the standard full-limb cast significantly (P < 0.001) reduced bone strain on the distal portion of the radius, third metacarpal bone, and first phalanx. Compared with the standard full-limb cast, the transfixation pin cast significantly (P < 0.001) reduced bone strain on the first phalanx.

Conclusion and Clinical Relevance

Compared with the standard full limb cast, the full-limb transfixation pin cast is more protective of the first phalanx. (Am J Vet Res 1998;59:197–200)

Free access
in American Journal of Veterinary Research