Determination of sulfachloropyridazine residue levels in feathers from broiler chickens after oral administration using liquid chromatography coupled to tandem mass spectrometry.

Several antimicrobials are routinely used by the poultry farming industry on their daily operations, however, researchers have found for some antimicrobials that their residues persist for longer periods in feathers than they do in edible tissues, and at higher concentrations, as well. But this information is not known for other classes of antimicrobials, such as the sulfonamides. Therefore, this work presents an accurate and reliable analytical method for the detection of sulfachloropyridazine (SCP) in feathers and edible tissues from broiler chickens. This method was also validated in-house and then used to study the depletion of sulfachloropyridazine in those matrices. The experimental group comprised 54 broiler chickens, who were raised under controlled conditions and then treated with a commercial formulation of 10% sulfachloropyridazine for 5 days. Samples were analyzed via LC-MS/MS, using 13C6-sulfamethazine (SMZ-13C6) as an internal standard. Aromatic sulfonic acid solid phase extraction (SPE) cartridges were used to clean up the samples. The Limit of Detection (LOD) for this method was set at 10 µg kg-1 on feathers and liver; and at 5 µg kg-1 on muscle. Within the range of 10-100 µg kg-1, the calibration curves for all matrices presented a determination coefficient greater than 0.96. Our results show, with a 95% confidence level, that sulfachloropyridazine persisted in feathers for up to 55 days after ceasing treatment, and its concentrations were higher than in edible tissues. In consequence, to avoid re-entry of antimicrobial residues into the food-chain, we recommend monitoring and inspecting animal diets that contain feather derivatives, such as feathers meals, because they could be sourced from birds that might have been medicated with sulfachloropyridazine.

Diagnosis and Management of Diabetes Mellitus in a Bali Mynah (Leucopsar rothschildi).

An 18-year-old female Bali mynah (Leucopsar rothschildi) was presented for polyphagia, weight loss, and incoordination. Diabetes mellitus was diagnosed based on the history and clinical findings, including persistent hyperglycemia with concurrent hypoinsulinemia and glucosuria. A treatment protocol was developed that led to improvement of clinical signs and management of hyperglycemia over several months. Because of the advanced age of the animal, difficulty in maintaining euglycemia, and the stress of handling and treatment, euthanasia was elected 167 days after initial presentation. At postmortem examination, no pancreatic lesions were detected histologically that would account for the diabetes mellitus. To our knowledge this is the first reported case of diabetes mellitus and clinical management of this condition in a passerine species.

Sustained availability of trimethoprim in drinking water to achieve higher plasma sulphonamide-trimethoprim antibacterial activity in broilers.

(1) In order to make trimethoprim (TMP) available to broilers throughout the day, a sustained release formulation (SRF) of the drug in the form of granules was added to the water tank that supplies drinking water. (2) Broilers were initially dosed with sulphachloropiridazine-TMP (SCP-TMP 5:1) and then further medicated throughout the day, achieving in the end a dose of 30 mg/kg each of SCP and TMP (group A). Group B received a preparation with the same dose of SCP and TMP (1:1) as group A, but administered as a single dose without the SRF of TMP. Group C received the customary SCP-TMP 5:1 preparation (30 and 6 mg/kg, respectively). Water tanks were completely consumed in 3 to 4 h. (3) Broilers were bled at different times and concentration of antibacterial activity in serum determined by correlating the composite antibacterial activity of SCP and TMP with actual concentrations of these drugs by means of a microbiological agar diffusion assay. (4) Time vs serum concentrations of activity were higher in group B; the increments in the maximum serum concentration for group B over groups A and C being 39 and 67%, respectively. (5) However, the sustained concentration of activity over time, measured as the area under the cu)rve, was highest in group A. Group B had higher values for area under the curve than group C. (6) An additional dose of TMP to achieve 30 mg/kg of both SCP and TMP improves the serum concentration of this combination over the customary 5:1 proportion. The best values for sustaining antibacterial activity were obtained using a 1:1 ratio as in group A. The use of a SRF as in group A may translate into better clinical results.

In vitro and in vivo binding of trimethoprim and sulphachlorpyridazine to equine food and digesta and their stability in caecal contents.

Binding of antibiotics to food has received little attention in equine medicine, although such binding could potentially reduce the bioavailability and clinical efficacy. In the present study, binding of trimethoprim (TMP) and sulphachlorpyridazine (SCP) to hay, grass silage and concentrate was investigated in vitro in buffer at pH 6.8 at different concentrations. The binding of TMP and SCP to caecal contents was also studied. In addition, the degradation of TMP and SCP by the caecal microflora was investigated by incubating sterilized and non-sterilized caecal contents for 3 h at 37 degrees C under anaerobic conditions and comparing the TMP and SCP contents. Further, a TMP/SCP powder formulation was adminstered orally with concentrate at a dose rate of 5 mg/kg TMP and 25 mg/kg SCP to three ponies with a caecum fistula; the animals were deprived of food for 8 h before administration. Blood samples, caecal contents samples and faecal samples were collected and analysed for TMP and SCP concentrations by means of high performance liquid chromatography (HPLC). Three non-fistulated ponies, acting as control animals, were fed the same dose of TMP/SCP with concentrate after 8 h of food deprivation and blood samples were taken. The percentage of in vitro binding of TMP as well as SCP to hay, grass silage and concentrate at concentrations of 4 micrograms/mL to 10 micrograms/mL was high (60-90%). TMP and SCP were also extensively bound to caecal contents (50-70%). At spiking concentrations above 10 micrograms/mL the percentage of binding decreased. There was no evidence of biodegradation of TMP or SCP in caecal contents. In vivo, both drugs could be detected in the caecal contents and in the faeces of three fistulated ponies. However, the fistulated ponies differed from the control ponies in that their TMP and SCP plasma concentrations were higher, and two fistulated ponies did not show double peaks in their plasma concentration-time curves. Therefore, the fistulated ponies did not provide an optimal model for in vivo binding studies. Despite this limitation, it can be concluded that binding of TMP and SCP to food is a major cause of the limited bioavailability of these drugs in the horse. It is hypothesized that the binding is reversible, and that a second absorption phase occurs in the large intestine, but part of the administered dose remains bound as both drugs were found in the faeces.

Pharmacokinetics of trimethoprim/sulphachlorpyridazine in horses after oral, nasogastric and intravenous administration.

In the present study, the pharmacokinetic parameters of a trimethoprim/sulphachlorpyridazine preparation following intravenous administration, administration by nasogastric tube and administration with concentrate were determined in the horse. Eight adult horses were dosed at 1 week intervals in a sequentially designed study at a dose of 5 mg/kg trimethoprim (TMP) and 25 mg/kg sulphachlorpyridazine (SCP) on all occasions. Plasma concentrations of both drugs were measured serially for 48 h. Pharmacokinetic parameters of clinical importance (distribution and elimination half-lives, clearance, bioavailability, volume of distribution) were determined both for TMP and SCP. Following intravenous administration, the volume of distribution at steady-state (Vd(ss)) was significantly larger for TMP (1.51 +/- 0.25 L/kg than for SCP (0.26 +/- 0.05 L/kg. The clearance was 7.73 +/- 2.26 mL/min.kg for TMP and 2.64 +/- 0.48 mL/min.kg for SCP. For both TMP and SCP, mean peak plasma concentrations (Cmax) and the bioavailabilities (F) were reduced significantly when the drugs were mixed with concentrate (ct) as compared with those after nasogastric administration (ngt) (Fct = 44.3 +/- 10.7% vs. Fngt = 68.3 +/- 12.5% for TMP; Fct = 46.3 +/- 8.9% vs. Fngt = 67.3 +/- 13.7% for SCP). Following the administration of TMP and SCP mixed with concentrate, the plasma concentration-time curves showed a biphasic absorption pattern in all horses. The first peak occurred 1-2 h and the second peak 8-10 h after administration of the combination preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic aspects of a sulphachloropyridazine trimethoprim preparation in normal and diseased fowl.

1. The pharmacokinetic and residue elimination patterns of sulphachloropyridazine appear to be modified by disease, even without affecting key organs essential for drug metabolism. 2. Drug kinetics and residue elimination data of a sulphachloropyridazine-trimethoprim preparation were compared using infectious coryza-affected (IC) fowl and healthy chickens. 3. The plasma concentrations of sulphachloropyridazine and trimethoprim were higher in affected animals, hence a reduced volume of distribution was obtained. 4. The half-life of sulphachloropyridazine and trimethoprim was reduced in IC-affected fowl and body clearance values were decreased. 5. The rate of drug residue elimination was noticeably slower in the IC-affected group. 6. These results indicate that drug elimination patterns in healthy and diseased animals are not the same.