PHARMACOKINETIC EVALUATION OF TRAMADOL AND ITS MAJOR METABOLITES AFTER SINGLE ORAL SUSTAINED TABLET ADMINISTRATION IN THE DOG: A PILOT STUDY

The study evaluated the pharmacokinetics of tramadol and its major metabolites O-desmethyltramadol (M1), N-desmethyltramadol (M2) and N–O didesmethyltramadol (M5) following a single oral administration of a sustained release (SR) 100 mg tablet to dogs. Plasma tramadol concentration was greater than the limit of quantification (LOQ) in three dogs, M1 was quantified only in one dog while M2 and M5 were quantified in all of the dogs. The median values of Cmax (maximum plasma concentration), Tmax (time to maximum plasma concentration) and T1/2 (half-life) for tramadol were 0.04 (0.17–0.02) lg mL1, 3 (4–2) and 1.88 (2.211–1.435) h, respectively. M5 showed median values of Cmax, Tmax and T1/2 of 0.1 (0.19–0.09) lg mL1, 2 (3–1) and 4.230 (6.583–1.847) h, respectively. M2 showed median values of Cmax, Tmax and T1/2 of 0.22 (0.330–0.080) lg mL1, 4 (7–3) and 4.487 (6.395–1.563) h, respectively. The findings suggest that the SR formulation of tramadol may not have suitable pharmacokinetic characteristics to be administered once-a-day as an effective and safe treatment for pain in the dog

PHARMACOKINETIC OF TRAMADOL AND ITS MAJOR CONJUGATES AFTER SINGLE PER OS ADMINISTRATION OF THE SUSTAINED TABLET AND PER RECTUM SUPPOSITORIES FORMULATIONS IN DOGS

The aim of the present study is to evaluate the pharmacokinetics of T and its major metabolites M1, M2 and M5 after the single oral administration of an SR tablet and rectal suppositories in dogs (4-6 mg•kg-1 m.c.). The plasma concentration data after SR-tablet and rectal administration were fitted on the basis of a mono- and non-compartmental model, respectively. T plasma concentration after SR tablet administration was quantitatively detected in three dogs, M1 was quantized in only one dog while M2 and M5 were quantized in all the dogs. T showed median values of Cmax, Tmax and T1/2 of 40 (20-170) ng•mL-1, 3 (4-2) and 1.88 (2.21-1.44) hours, respectively. M5 showed median values of Cmax, Tmax and T1/2 of 0.1 (90-190) ng•mL-1, 2 (3-1) and 4.23 (6.58-1.85) hours, respectively. M2 showed median values of Cmax, Tmax and T1/2 of 220 (80-330) ng•mL-1, 4 (7-3) and 4.49 (6.39-1.57) hours, respectively. Following rectal administration, T was detected from 5 minutes up to 10 h in a smaller amount than M5 and M2. T median value of Cmax was 140±60 ng•mL-1 in 0.56±0.41 h (Tmax). K01 t1/2 and K10 t1/2 were 0.27±0.25 h and 2.24±1.82h, respectively. M1 was detectable from 5 min up to 2 h, showing low values (7-28 ng•mL-1). The present findings suggest oral SR tablet and suppository rectal formulation have similar pharmacokinetic behavior and would not have suitable pharmacokinetic characteristics to be administered once-a-day as an effective and safe treatment for pain in dogs

Danofloxacin pharmacokinetics and tissue residues in Bilgorajska geese

Danofloxacin is a fluoroquinolone developed for veterinary medicine and used in avian species for the treatment of numerous bacterial infections. However, no pharmacokinetic data have been reported in geese. The aim of the study was three-fold: (i) to evaluate the pharmacokinetics of danofloxacin in geese after single oral (PO) and intravenous (IV) administrations; (ii) to define its residue depletion profile in different goose tissues, and (iii) to recreate a multiple-dose simulation in the practical context of large-scale breeding. Twenty-four healthy geese were randomly divided in three groups each composed of eight animals. Group 1 received danofloxacin IV (5 mg/kg) and groups 2 and 3 were treated PO with the same dose. Blood was collected until 24 h (IV; group 1) and 48 h (PO; group 2) after administration. Two animals from group 3 were sacrificed at 6, 10, 24 and 48 h to collect samples of muscle, heart, kidney, liver, and lung. Danofloxacin was quantified in each matrix using a validated high-performance liquid chromatography method with spectrofluorimetric detection and the pharmacokinetic analysis was performed using non-compartmental and compartmental approaches. Danofloxacin showed a moderate elimination half-life (6.61 h), a slow clearance (0.35 mL/g*h) and a large volume of distribution (1.46 mL/g). The peak plasma concentration after PO administration and the time to reach it were 0.96 μg/mL and 1.70 h, respectively. The oral bioavailability was moderate (58%). Higher residue concentration was found in liver and kidney, compared to the other tissues. If the AUC(0–24) value found in the present study is included in the pharmacokinetic/pharmacodynamic index (AUC(0–24)/MIC) for the prediction of fluoroquinolones' efficacy, danofloxacin seems to be effective in geese against gram-negative bacteria with a minimum inhibitory concentration (MIC) < 0.076 μg/mL and against S. pneumoniae with a MIC < 0.29 μg/mL after a single PO dose of 5 mg/kg. Liver and kidney showed the highest drug tissue penetration value, with an explorative withdrawal time of 2.6 and 3.8 days, respectively. A practical multiple-dose regimen simulation does not lead to significant plasma drug accumulation

Pharmacokinetic and urine profile of tramadol and its major metabolites following oral immediate release capsules administration in dogs

The aim of the present paper was to test the oral administration of oral immediate release capsules of tramadol in dogs, to asses both its pharmacokinetic properties and its urine profile. After capsules administration of tramadol (4 mg/kg), involving eight male Beagle dogs, the concentration of tramadol and its main metabolites, M1, M2 and M5, were determined in plasma and urine using an HPLC method. The plasma concentrations of tramadol and metabolites were fitted on the basis of mono- and non-compartmental models, respectively. Tramadol was detected in plasma from 5 min up to 10 h in lesser amounts than M5 and M2, detected at similar concentrations, while M1 was detected in negligible amounts. In the urine, M5 and M1 showed the highest and smallest amount, respectively; M1 and M5 resulted widely conjugate with glucuronic acid. In conclusion, after oral administration of tramadol immediate release capsules, the absorption of the active ingredient was rapid, but its rapid metabolism quickly transformed the parental drug to high levels of M5 and M2, showing an extensive elimination via the kidney. Hence, in the dog, the oral immediate release pharmaceutical formulation of tramadol would have different pharmacokinetic behaviour than in humans