Determination of tigecycline in turkey plasma by LC-MS/MS: validation and application in a pharmacokinetic study

Tigecycline (TIG), a novel glycylcycline antibiotic, plays an important role in the management of complicated skin and intra-abdominal infections. The available data lack any description of a method for determination of TIG in avian plasma. In our study, a selective, accurate and reversed-phase high performance liquid chromatography-tandem mass spectrometry method was developed for the determination of TIG in turkey plasma. Sample preparation was based on protein precipitation and liquid-liquid extraction using 1,2-dichloroethane. Chromatographic separation of TIG and minocycline (internal standard, IS) was achieved on an Atlantis T3 column (150 mm x 3.0 mm, 3.0 μm) using gradient elution. The selected reaction monitoring transitions were performed at 293.60 m/z → 257.10 m/z for TIG and 458.00 m/z → 441.20 m/z for IS. The developed method was validated in terms of specificity, selectivity, linearity, lowest limit of quantification, limit of detection, precision, accuracy, matrix effect, carry-over effect, extraction recovery and stability. All parameters of the method submitted to validation met the acceptance criteria. The assay was linear over the concentration range of 0.01-100 μg/ml. This validated method was successfully applied to a TIG pharmacokinetic study in turkey after intravenous and oral administration at a dose of 10 mg/kg at various time-points

Pharmacological characteristics of metamizole

Metamizole (dipyrone) is a popular analgetic, non-opioid drug, commonly used in human and veterinary medicine. In some cases, this agent is still incorrectly classified as a non-steroidal anti-inflammatory drug (NSAID). Metamizole is a pro-drug, which spontaneously breaks down after oral administration to structurally related pyrazolone compounds. Apart from its analgesic effect, the medication is an antipyretic and spasmolytic agent. The mechanism responsible for the analgesic effect is a complex one, and most probably rests on the inhibition of a central cyclooxygenase-3 and activation of the opioidergic system and cannabinoid system. Metamizole can block both PG-dependent and PG-independent pathways of fever induced by LPS, which suggests that this drug has a profile of antipyretic action distinctly different from that of NSAIDs. The mechanism responsible for the spasmolytic effect of metamizole is associated with the inhibited release of intracellular Ca²⁺ as a result of the reduced synthesis of inositol phosphate. Metamizole is predominantly applied in the therapy of pain of different etiology, of spastic conditions, especially affecting the digestive tract, and of fever refractory to other treatments. Co-administration of morphine and metamizole produces superadditive, antinociceptive effects. Metamizole is a relatively safe pharmaceutical preparation although it is not completely free from undesirable effects. Among these side-effects, the most serious one that raises most controversy is the myelotoxic effect. It seems that in the past the risk of metamizole- induced agranulocytosis was exaggerated. Despite the evidence showing no risk of teratogenic and embryotoxic effects, the drug must not be administered to pregnant women, although it is allowed to be given to pregnant and lactating animals. This paper seeks to describe the characteristics of metamizole in the light of current knowledge

Prostaglandin E2 inhibits IL-10 production by bovine CD4plus T cells

Although prostaglandin E₂ (PGE₂) is a pro-inflammatory mediator, it also produces some effect which is anti-inflammatory in character. It is suggested that one of the mechanisms responsible for the latter effect is the increased synthesis of IL-10. The aim of this study has been to determine the influence of PGE₂ on IL-10 production by bovine CD⁴⁺ and CD⁸⁺ T cells and NK cells. With this aim, peripheral blood mononuclear cells collected from 12-month-old heifers (n = 10) were treated without or with PGE₂ (10⁻⁶ M). Flow cytometric analysis showed that PGE₂ caused a reduction in the percentage of IL-10 producing CD⁴⁺ T cells (P < 0.001), while leaving the secretion of this cytokine by CD⁸⁺ T cells and NK cells unaffected. This seems to indicate that PGE₂ in cattle does not produce an anti-inflammatory effect by increasing the synthesis of IL-10; contrary to this, it may aggravate an inflammatory response by inhibiting the secretion of this cytokine by CD⁴⁺ T cells

Characteristics of selected second-generation antiepileptic drugs used in dogs

A significant number of cases of clinical canine epilepsy remain difficult to control in spite of the applied treatment. At the same time, the range of antiepileptic drugs is increasingly wide, which allows efficient treatment. In the present paper we describe the pharmacodynamics and pharmacokinetics of the newer antiepileptic drugs which were licensed after 1990 but are still not widely used in veterinary medicine. The pharmacokinetic profiles of six of these drugs were tested on dogs. The results of experimental studies suggest that second generation antiepileptic drugs may be applied in mono- as well as in poli- treatment of canine epilepsy because of the larger safety margin and more advantageous pharmacokinetic parameters. Knowledge of the drugs’ pharmacokinetics allows its proper clinical appliance, which, in turn, gives the chance to improve the efficiency of pharmacotherapy of canine epilepsy

Pharmacokinetics of orally administered simvastatin in turkeys

The aim of the present study was to determine the pharmacokinetics of simvastatin (SIM) administered orally in 6-week-old turkeys at a single dose of 2 mg/kg b.w. The SIM concentrations in plasma were determined by validated HPLC-MS/MS method. Mean (± SD; n = 10) values of pharmacokinetic parameters evaluated were as follows: Cmax = 0.49 ± 0.21 ng/ml, tmax = 1.6 ± 1.1 h, AUC(0-∞) = 1.08 ± 0.57 h×ng/ml, t1/2kel = 2.14 ± 1.3 h and MRT = 3.08 ± 1.52 h. The results indicate that the SIM is absorbed from the gastrointestinal tract of turkeys; however, achieved plasma level is lower compared to those observed in mammals

A comparison of the efficacy and pharmacokinetics of ivermectin after spring and autumn treatments against Cyathostominae in horses

The aim of the present study was to determine the efficacy of ivermectin against Cyathostominae infections and to describe the drug's pharmacokinetic parameters during two seasonal deworming treatments in horses. The study was performed on warm-blooded mares aged 3-12 years weighing 450-550 kg. A single bolus of an oral paste formulation of ivermectin was administered at a dose of 0.2 mg/kg BW in spring and autumn. Fecal samples were tested before treatment and 1, 2, 3, 4, 6, 10, 20, 30, 40, 50, 60, 75 days after treatment. Ivermectin concentrations in blood samples collected before treatment, 0.5,1, 2, 3, 4, 6, 12, 24, 36 and 48 hours after treatment, and 3, 4, 6, 8,10, 15, 20, 25, 30, 40, 50, 60 and 75 days after drug administration were determined by high pressure liquid chromatogra-phy. Drug absorption was significantly (p<0.05) slower (tmax: 21.89±11.43 h) in autumn than in spring (tmax: 9.78±8.97 h). Maximum concentrations (Cmax) of ivermectin in the blood plasma of individual horses (8.40-43.08 ng/ml) were observed 2-24 h after drug administration during the spring treatment and 2-36 h (6.43-24.86 ng/ml) after administration during the autumn treatment. Significantly higher (p<0.05) ivermectin concentrations were found during the first 4 hours after administration in spring in comparison with those determined after the autumn treatment. The administration of the recommended dose of ivermectin resulted in 100% elimination of parasitic eggs from feces in spring and autumn treatment