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
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)
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.
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)
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.
Objective—–To compare transfixation and standard
full-limb casts for prevention of in vitro displacement
of a mid-diaphyseal third metacarpal osteotomy site
Sample Population—6 forelimbs from 6 horses
euthanatized for reasons not related to the musculoskeletal
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
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)