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- Author or Editor: Ian Hawkins x
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Abstract
In collaboration with the American College of Veterinary Pathologists
Abstract
Objective—To determine the pharmacokinetics of butorphanol tartrate after IV and IM single-dose administration in red-tailed hawks (RTHs) and great horned owls (GHOs).
Animals—6 adult RTHs and 6 adult GHOs.
Procedures—Each bird received an injection of butorphanol (0.5 mg/kg) into either the right jugular vein (IVj) or the pectoral muscles in a crossover study (1-week interval between treatments). The GHOs also later received butorphanol (0.5 mg/kg) via injection into a medial metatarsal vein (IVm). During each 24-hour postinjection period, blood samples were collected from each bird; plasma butorphanol concentrations were determined via liquid chromatography-mass spectrometry.
Results—2- and 1-compartment models best fit the IV and IM pharmacokinetic data, respectively, in both species. Terminal half-lives of butorphanol were 0.94 ± 0.30 hours (IVj) and 0.94 ± 0.26 hours (IM) for RTHs and 1.79 ± 1.36 hours (IVj), 1.84 ± 1.56 hours (IM), and 1.19 ± 0.34 hours (IVm) for GHOs. In GHOs, area under the curve (0 to infinity) for butorphanol after IVj or IM administration exceeded values in RTHs; GHO values after IM and IVm administration were less than those after IVj administration. Plasma butorphanol clearance was significantly more rapid in the RTHs. Bioavailability of butorphanol administered IM was 97.6 ± 33.2% (RTHs) and 88.8 ± 4.8% (GHOs).
Conclusions and Clinical Relevance—In RTHs and GHOs, butorphanol was rapidly absorbed and distributed via all routes of administration; the drug's rapid terminal half-life indicated that published dosing intervals for birds may be inadequate in RTHs and GHOs.
Abstract
Objective—To determine the stability and distribution of voriconazole in 2 extemporaneously prepared (compounded) suspensions stored for 30 days at 2 temperatures.
Sample Population—Voriconazole suspensions (40 mg/mL) compounded from commercially available 200-mg tablets suspended in 1 of 2 vehicles. One vehicle contained a commercially available suspending agent and a sweetening syrup in a 1:1 mixture (SASS). The other vehicle contained the suspending agent with deionized water in a 3:1 mixture (SADI).
Procedures—Voriconazole suspensions (40 mg/mL in 40-mL volumes) were compounded on day 0 and stored at room temperature (approx 21°C) or refrigerated (approx 5°C). To evaluate distribution, room-temperature aliquots of voriconazole were measured immediately after preparation. Refrigerated aliquots were measured after 3 hours of refrigeration. To evaluate stability, aliquots from each suspension were measured at approximately 7-day intervals for up to 30 days. Voriconazole concentration, color, odor, opacity, and pH were measured, and aerobic and anaerobic bacterial cultures were performed at various points.
Results—Drug distribution was uniform (coefficient of variation, < 5%) in both suspensions. On day 0, 87.8% to 93.0% of voriconazole was recovered; percentage recovery increased to between 95.1% and 100.8% by day 7. On subsequent days, up to day 30, percentage recovery was stable (> 90%) for all suspensions. The pH of each suspension did not differ significantly throughout the 30-day period. Storage temperature did not affect drug concentrations at any time, nor was bacterial growth obtained.
Conclusions and Clinical Relevance—Extemporaneously prepared voriconazole in SASS and SADI resulted in suspensions that remained stable for at least 30 days. Refrigerated versus room-temperature storage of the suspensions had no effect on drug stability.
Abstract
Objective—To determine dispersion uniformity and stability of meloxicam and carprofen in extemporaneous preparations stored for 28 days.
Design—Prospective study.
Sample Population—Meloxicam and carprofen (commercial formulations) were compounded (day 0) with deionized water (DW), 1% methylcellulose gel (MCG), MCG and simple syrup (SS; 1:1 mixture), or a suspending and flavoring vehicle combination (SFVC; 1:1 mixture) to nominal drug concentrations of 0.25, 0.5, or 1.0 mg/mL and 1.25, 2.5, or 5.0 mg/mL, respectively.
Procedures—Preparations were stored at approximately 4°C (39.2°F) or 22°C (71.6°F). For each preparation, drug concentrations were determined and drug stability was evaluated at intervals during storage; on days 0 and 28, pH values were measured and bacterial cultures were initiated.
Results—In meloxicam-DW, meloxicam-MCG (0.25 mg/mL), and meloxicam-MCG (0.5 mg/mL) preparations, drug distribution was uniform (coefficient of variation < 10%); > 90% of the original drug concentration was maintained for 28 days. Despite uniform drug distribution of the carprofen-SFVC preparations, most retained ≥ 90% of the original drug concentration for only 21 days. Use of the MCG-SS combination resulted in foamy preparations of unacceptable variability. After 28 days, pH decreased slightly in meloxicam-DW and meloxicam-MCG preparations (0.17 ± 0.04 and 0.21 ± 0.04, respectively). Carprofen-SFVC (2.5 mg/mL) and carprofen-MCG-SS (5.0 mg/mL) preparations stored at 22°C for 28 days yielded bacterial growth.
Conclusions and Clinical Relevance—DW, MCG, and the SFVC can be used successfully for extemporaneous preparation of meloxicam and carprofen for administration to small exotic animals. Refrigeration is recommended for preparations of meloxicam-DW and carprofen-SFVC.
Abstract
Case Description—A 7-year-old Quarter Horse gelding was hospitalized in Ocala, Fla, because of lethargy, fever, anorexia, and swelling of distal aspects of the limbs. A tentative diagnosis of equine piroplasmosis (EP) was made on the basis of examination of a blood smear. The case was reported to the Florida State Veterinarian, and infection with Babesia equi was confirmed. The subsequent investigation included quarantine and testing of potentially exposed horses for B equi and Babesia caballi infections, tick surveillance, and owner-agent interviews.
Clinical Findings—210 horses on 25 premises were tested for infection with EP pathogens. Twenty B equi–infected horses on 7 premises were identified; no horses tested positive for B caballi. Seven horses, including the index case, had clinical findings consistent with EP Dermacentor variabilis was considered the only potential tick vector for B equi collected, and all D variabilis specimens tested negative for Babesia organisms via PCR assay. Results of the epidemiological investigation suggested that B equi was spread by use of shared needles and possibly blood transfusions. All horses that tested positive were involved in nonsanctioned Quarter Horse racing, and management practices were thought to pose substantial risk of transmission of blood-borne pathogens.
Treatment and Outcome—Final outcome of B equi–infected horses was euthanasia, death from undetermined causes, or shipment to a US federal research facility.
Clinical Relevance—This investigation highlights the importance of collaboration between private veterinary practitioners, state veterinary diagnostic laboratories, and regulatory officials in the recognition, containment, and eradication of foreign animal disease.
