Search Results

Abstract

Objective—To evaluate the stability and retention of viscous formulations of the antifungal drug clotrimazole in vitro and to evaluate retention times, absorption, and histologic response to these compounds when placed in the frontal sinus of dogs.

Animals—6 male Beagles.

Procedures—1% clotrimazole gels were formulated with hydroxypropyl cellulose, poloxamer, and carboxymethylcellulose sodium bases. Commercially available 1% clotrimazole creams were also evaluated. Each compound was incubated at 37°C in a funnel. Volume retained and clotrimazole stability were evaluated for 4 weeks. Six compounds were then chosen for in vivo evaluation. The frontal sinuses of 6 dogs were filled with 1 of the 6 compounds. Computed tomographic evaluation was performed weekly for up to 4 weeks to evaluate gel retention. Blood samples were collected to evaluate clotrimazole absorption. Following euthanasia, sinuses were examined histologically.

Results—Commercially available clotrimazole creams were not retained in funnels in vitro. In vivo, hydroxypropyl cellulose– and carboxymethylcellulose-based gels resulted in the most severe inflammatory response and were retained the longest. Poloxamer-based gels had a shorter retention time and were associated with less inflammation. Clotrimazole was minimally absorbed. Despite a marked inflammatory response to several of the clotrimazole-containing gels, no notable adverse clinical responses were observed.

Conclusions and Clinical Relevance—Poloxamer gels had the most promise for improving drug contact within the frontal sinus of dogs, while limiting the inflammatory response. Poloxamer gels have the additional benefit of improved handling as a result of reverse gelation (ie, they gel when warmed to 37°C).

Abstract

OBJECTIVE To describe concentration-over-time data for ampicillin and sulbactam in the digital and systemic circulations and synovial fluid (SYN) of cattle following a single injection of ampicillin-sulbactam as a regional IV perfusion (RIVP).

ANIMALS 6 healthy adult nonlactating Jersey-crossbred cows.

PROCEDURES The right hind limb of each cow was aseptically prepared. A tourniquet was applied around the midmetatarsal region, and 1.0 g of ampicillin with 0.5 g of sulbactam in a combined formulation was administered as an RIVP into the dorsal common digital vein (DCDV). Blood samples from the DCDV and jugular vein and SYN samples from the metatarsophalangeal joint of the prepared limb were collected immediately before and at predetermined times for 24 hours after RIVP. One blood sample was obtained from the abaxial proper plantar vein of the lateral digit of the prepared limb 0.25 hours after RIVP. Serum and SYN ampicillin and sulbactam concentrations were determined by high-performance liquid chromatography.

RESULTS Mean ± SD maximum concentration of ampicillin in SYN and serum obtained from the abaxial proper plantar and jugular veins was 1,995 ± 1,011 μg/mL, 5,422 ± 1,953 μg/mL, and 2.5 ± 1.6 μg/mL, respectively. Corresponding serum and SYN concentrations of sulbactam were lower but followed the same pattern over time as those for ampicillin. Synovial fluid ampicillin concentration remained above 8 μg/mL for a mean time of 18.9 hours.

CONCLUSIONS AND CLINICAL RELEVANCE Potentially therapeutic concentrations of ampicillin were achieved in regional serum and SYN samples; SYN concentrations remained at potentially therapeutic values for > 12 hours following RIVP of 1.5 g of ampicillin-sulbactam in the hind limb of healthy cows.

Abstract

Objective—To evaluate the stability of 3 extemporaneous oral suspensions of enrofloxacin mixed with readily available flavoring vehicles when stored at room temperature (approx 22°C).

Design—Evaluation study.

Samples—3 commonly compounded oral suspensions of enrofloxacin.

Procedures—On day 0, commercially available enrofloxacin tablets were compounded with a mixture of distilled water and corn syrup (formulation A) or cherry syrup (formulation B) flavoring vehicles to create suspensions with a nominal enrofloxacin concentration of 22.95 mg/mL, and 2.27% enrofloxacin injectable solution was compounded with a liquid sweetener (formulation C) to create a suspension with a nominal enrofloxacin concentration of 11.35 mg/mL. Preparations were stored in amber-colored vials at room temperature for 56 days. For each preparation, the enrofloxacin concentration was evaluated with high-performance liquid chromatography at prespecified intervals during the study. The pH, odor, and consistency for all suspensions were recorded at the start and completion of the study.

Results—Relative to the nominal enrofloxacin concentration, the enrofloxacin concentration strength ranged from 95.80% to 100.69% for formulation A, 108.44% to 111.06% for formulation B, and 100.99% to 103.28% for formulation C. A mild pH increase was detected in all 3 suspensions during the study.

Conclusions and Clinical Relevance—Results indicated that, when stored in amber-colored vials at room temperature for 56 days, the enrofloxacin concentration strength in all 3 formulations was retained within acceptance criteria of 90% to 110%. Subjectively, cherry syrup flavoring was better at masking the smell and taste of enrofloxacin than were the other mixing vehicles.

Abstract

OBJECTIVE To determine the pharmacokinetics of a single dose of meloxicam after IM and oral administration to healthy lesser flamingos (Phoeniconaias minor) by use of a population approach.

ANIMALS 16 healthy captive lesser flamingos between 1 and 4 years of age.

PROCEDURES A single dose of meloxicam (0.5 mg/kg) was administered IM to each bird, and blood samples were collected from birds at 3 (n = 13 birds), 2 (2), or 1 (1) selected point between 0 and 13 hours after administration, with samples collected from birds at each point. After a 15-day washout period, the same dose of meloxicam was administered PO via a red rubber tube and blood samples were collected as described for IM administration. Pharmacokinetic values were determined from plasma concentrations measured by high-performance liquid chromatography.

RESULTS Plasma drug concentrations after IM administration of meloxicam reached a mean ± SD maximum value of 6.01 ± 3.38 μg/mL. Mean area under the concentration-versus-time curve was 17.78 ± 2.79 μg•h/mL, and mean elimination half-life was 1.93 ± 0.32 hours. Plasma concentrations after oral administration reached a mean maximum value of 1.79 ± 0.33 μg/mL. Mean area under the curve was 22.16 ± 7.17 μg•h/mL, and mean elimination half-life was 6.05 ± 3.53 hours.

CONCLUSIONS AND CLINICAL RELEVANCE In lesser flamingos, oral administration of meloxicam resulted in higher bioavailability and a longer elimination half-life than did IM administration, but the maximum plasma concentration was low and may be insufficient to provide analgesia in flamingos. Conversely, IM administration achieved the desired plasma concentration but would require more frequent administration.

Abstract

OBJECTIVE To investigate in vitro carboplatin release from 6 carrier media.

SAMPLE 6 carboplatin-containing carrier media.

PROCEDURES An in vitro release study was performed with 6 commercially available carrier media: a hemostatic gelatin sponge, a poloxamer copolymer gel, and 2 sizes (3 and 4.8 mm in diameter) of beads molded from each of 2 commercial calcium sulfate products. All carrier media contained 10 mg of carboplatin. Carrier media specimens were placed in 37°C PBS solution for 96 hours. Carboplatin concentrations in PBS solution were measured by use of high-performance liquid chromatography at 15 time points to calculate the amount and proportion of carboplatin released from each specimen.

RESULTS Peak release of carboplatin from the poloxamer copolymer gel and hemostatic gelatin sponge were achieved after 4 and 20 hours, respectively. Maximum release did not differ significantly between the poloxamer copolymer gel and hemostatic gelatin sponge, but both released significantly more carboplatin within 96 hours than did both of the commercial calcium sulfate products. The poloxamer copolymer gel released 99% of the carboplatin, and the hemostatic gelatin sponge released 68.5% of the carboplatin. Peak release of carboplatin from the calcium sulfate beads was not reached within 96 hours.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, carboplatin release from the hemostatic gelatin sponge was incomplete. The poloxamer copolymer gel and hemostatic gelatin sponge released carboplatin rapidly in vitro, whereas calcium sulfate beads did not.

Abstract

Abstract

Objective—To evaluate the use of adult cat serum as an immunoglobulin supplement in kittens with failure of passive transfer.

Design—Randomized controlled study.

Animals—11 specific pathogen-free queens and their 43 kittens.

Procedure—Kittens were removed from the queens at birth, prior to suckling colostrum, and randomly assigned to 1 of 4 groups: colostrum-deprived, colostrum-fed, colostrum-deprived and administration of pooled adult cat serum IP, and colostrum-deprived and administration of pooled adult serum SC. Colostrum-fed kittens were returned to the queen and allowed to suckle normally. Colostrum-deprived kittens were isolated from the queen and fed a kitten milk replacer for 2 days to prevent absorption of colostral IgG. All colostrum-deprived kittens were returned to the queen on day 3. Serum IgG concentrations were measured by radial immunodiffusion in the kittens at birth and 2 days and 1, 2, 4, 6, and 8 weeks after birth.

Results—None of the kittens had detectable serum IgG at birth. Both IP and SC administration of adult cat serum resulted in peak serum IgG concentrations equivalent to those in kittens that suckled normally. Untreated colostrum-deprived kittens did not achieve serum IgG concentrations comparable to those for kittens in the other groups until 6 weeks of age.

Conclusions and Clinical Relevance—Results suggest that adult cat serum may be used as an immunoglobulin supplement in colostrum-deprived kittens. Although the minimum concentration of IgG necessary to protect kittens from infection is unknown, concentrations achieved were comparable to those in kittens that suckled normally. (J Am Vet Med Assoc 2001;219:1401–1405)

Abstract

Objective—To assess the pharmacokinetics and pharmacodynamics of morphine in llamas.

Animals—6 healthy adult llamas.

Procedures—Llamas received morphine sulfate in a randomized crossover design. In phase 1, they received IV or IM administration of morphine at 0.05 or 0.5 mg/kg, respectively; in phase 2, they received IV administration of morphine at 0.05, 0.25, or 0.5 mg/kg. Plasma morphine and morphine-6-glucuronide concentrations were determined by validated methods. Body temperature, heart rate, respiratory rate, sedation, and analgesia were assessed and compared with plasma concentrations by regression analysis.

Results—Total body clearance was similar between IV administration of morphine sulfate at 0.25 and 0.5 mg/kg (mean ± SD, 25.3 ± 6.9 mL/min/kg and 27.3 ± 5.9 mL/min/kg, respectively), and linearity was demonstrated between these doses. Bioavailability of morphine following IM administration at 0.5 mg/kg was 120 ± 30%. Body temperature and sedation increased as the dose of morphine administered increased. Heart rate was unaffected by varying doses. Respiratory rate decreased as dose increased. Analgesia was difficult to assess as a result of high individual variability. Intravenous administration of morphine at 0.25 mg/kg provided the most consistent increase in tolerance to electric stimulation. Pharmacodynamic modeling revealed a sigmoidal relationship between plasma concentration and sedation score.

Conclusions and Clinical Relevance—Morphine was characterized by a large apparent volume of distribution and high systemic clearance in llamas. A prolonged half-life was observed with IM injection. Intravenous administration of morphine sulfate at 0.25 mg/kg every 4 hours is suggested for further study.

Abstract

Objective—To compare the pharmacokinetic properties and bioavailability following oral and IV administration of bisoprolol, a second-generation β₁-adrenoceptor–selective blocking agent, with those of carvedilol, a third-generation β₁/β₂ and α₁-adrenoceptor blocking agent, in dogs.

Animals—12 healthy adult Beagles.

Procedures—A prospective, parallel group study was performed. The dogs were allocated to 1 of 2 groups (6 dogs/group) and were administered orally a 1 mg/kg dose of either bisoprolol or carvedilol. Following a 1-week washout period, each cohort received a 1 mg/kg dose of the same drug IV. Blood samples were collected before and after drug administration, and serum concentrations, pharmacokinetic variables, and bioavailability for each agent were assessed.

Results—After oral administration of bisoprolol, the geometric mean value of the area under the concentration-time curve extrapolated to infinity (AUCinf) was 2,195 μg/L (coefficient of variation [CV], 15%). After IV administration of bisoprolol, the dose-normalized geometric mean AUCinf was 2,402 μg/L (CV, 19%). Oral bioavailability of bisoprolol was 91.4%. After oral administration of carvedilol, the geometric mean AUCinf was 70 μg/L (CV, 81%). After IV administration of carvedilol, the geometric mean AUCinf was 491 μg/L (CV, 23%). Oral bioavailability of carvedilol was 14.3%. Total body clearance was low (0.42 L/h/kg) for bisoprolol and high (2.0 L/h/kg) for carvedilol.

Conclusions and Clinical Relevance—After oral administration, carvedilol underwent extensive first-pass metabolism and had limited bioavailability; bisoprolol had less first-pass effect and higher bioavailability. Collectively, these differences suggested that, in dogs, bisoprolol has less interindividual pharmacokinetic variability, compared with carvedilol.

Abstract

Objective—To determine the pharmacokinetics and safety of voriconazole administered orally in single and multiple doses in Hispaniolan Amazon parrots (Amazona ventralis).

Animals—15 clinically normal adult Hispaniolan Amazon parrots.

Procedures—Single doses of voriconazole (12 or 24 mg/kg) were administered orally to 15 and 12 birds, respectively; plasma voriconazole concentrations were determined at intervals via high-pressure liquid chromatography. In a multiple-dose trial, voriconazole (18 mg/kg) or water was administered orally to 6 and 4 birds, respectively, every 8 hours for 11 days (beginning day 0); trough plasma voriconazole concentrations were evaluated on 3 days. Birds were monitored daily, and clinicopathologic variables were evaluated before and after the trial.

Results—Voriconazole elimination half-life was short (0.70 to 1.25 hours). In the single-dose experiments, higher drug doses yielded proportional increases in the maximum plasma voriconazole concentration (C_max) and area under the curve (AUC). In the multiple-dose trial, C_max, AUC, and plasma concentrations at 2 and 4 hours were decreased on day 10, compared with day 0 values; however, there was relatively little change in terminal half-life. With the exception of 1 voriconazole-treated parrot that developed polyuria, adverse effects were not evident.

Conclusions and Clinical Relevance—In Hispaniolan Amazon parrots, oral administration of voriconazole was associated with proportional kinetics following administration of single doses and a decrease in plasma concentration following administration of multiple doses. Oral administration of 18 mg of voriconazole/kg every 8 hours would require adjustment to maintain therapeutic concentrations during long-term treatment. Safety and efficacy of voriconazole treatment in this species require further investigation.