Simultaneous quantification and confirmation of oxycodone and its metabolites in equine urine using ultra-high performance liquid chromatography-tandem mass spectrometry.

Oxycodone, an opioid commonly used to treat pain in humans, has the potential to be abused in racehorses to enhance their performance. To understand the pharmacokinetics of oxycodone and its metabolites in horses, as well as to detect the illegal use of oxycodone in racehorses, a method for quantification and confirmation of oxycodone and its metabolites is needed. In this study, we developed and validated an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method that can simultaneously quantify and confirm oxycodone and eight metabolites in equine urine. Samples were subjected to enzymatic hydrolysis and then liquid-liquid extraction using ethyl acetate. The analyte separation was achieved on a Hypersil Gold C18 sub-2 µm column and analytes were detected on a triple quadrupole mass spectrometer. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 25-50 pg/mL and 100 pg/mL, respectively. Excellent linearity of the calibration curves was observed over a range of 100-10000 pg/mL for all nine analytes. Retention time, signal-to-noise ratio, and product ion ratios were utilized as confirmation criteria, with the limits of confirmation (LOC) ranging from 100 to 250 pg/mL. The data from a pilot pharmacokinetic (PK) study suggested that oxycodone metabolites have longer detection periods in equine urine compared to oxycodone itself; thus, the detection of metabolites in equine urine extends the ability to detect oxycodone exposure in racehorses.

Single-dose nonsteroidal anti-inflammatory drugs in horses have no impact on concentrations of cytokines or growth factors in autologous protein solution and platelet-rich plasma.

OBJECTIVE: To determine the effects of a single dose of the NSAIDs phenylbutazone, firocoxib, flunixin meglumine, and ketoprofen on concentrations of growth factors and cytokines in autologous protein solution (APS) and platelet-rich plasma (PRP). ANIMALS: 6 adult university-owned horses. METHODS: For the first phase, 6 horses were randomized to receive ketoprofen (1,000 mg) or flunixin meglumine (500 mg) IV. Blood was obtained and processed for APS (Pro-Stride) and PRP (Restigen) before and 6 hours after administration of NSAIDs. Horses underwent a 2-week washout period, after which the protocol was repeated using a crossover design. For the second phase, following at least a 2-week washout period, the study protocol was repeated with phenylbutazone (1 g) or firocoxib (57 mg) administered orally. Plasma was collected 6 hours after administration for evaluation of drug concentrations, and APS and PRP were analyzed for concentrations of drug, platelets, leukocytes, and several growth factors and cytokines (PDGF, fibroblast growth factor, TGF-ß1, IL-1ß, IL-10, IL-6, IL-8, and tumor necrosis factor-α) before and 6 hours after administration of NSAIDs using immunoassays. RESULTS: There were no significant differences in concentrations of cytokines or growth factors before or after administration of any NSAID. There were significant differences in concentrations of leukocytes and platelets based on both product and time. NSAID concentrations in plasma were not significantly different from concentrations in APS and PRP. CLINICAL RELEVANCE: These results help guide clinicians on the appropriate use of these NSAIDs in conjunction with the processing of APS and PRP, which is unlikely to significantly alter the final product after single-dose administration.

Use of Liquid Chromatography--Tandem Mass Spectrometry to Quantify and Confirm the Fentanyl Metabolite N-[1-(2-Phenethy-4-Piperidinyl)] Maloanilinic Acid in Equine Urine for Doping Control.

Fentanyl, a powerful synthetic mu opioid receptor agonist, is banned in equine sports by the Association of Racing Commissioners International and the Fédération Équestre Internationale. The presence of fentanyl in equine blood has been confirmed during routine post-race screening for doping substances in the authors' laboratory. While fentanyl can be detected and confirmed in blood, it is rapidly metabolized, and screening for the metabolite N-[1-(2-phenethy-4-piperidinyl)] maloanilinic acid (PMA) in equine urine is expected to allow for a longer detection time. In this study, a quantitative and confirmatory liquid chromatography--tandem mass spectrometry (LC-MS-MS) method was developed for PMA analysis in equine urine. PMA was extracted by solid phase extraction, separated on a C18 column and detected using a triple quadrupole mass spectrometer. The mass spectrometer was operated in positive-ion mode, and multiple reaction monitoring was used to monitor product ions m/z 188, m/z 281 and m/z 323. The method was validated for extraction recovery, matrix effect, specificity, sensitivity, precision and accuracy, carryover and processed sample stability according to the guidelines of the US Food and Drug Administration for bioanalysis. The limits of detection and quantification were 5 and 10 pg/mL, respectively. Linearity was obtained over the concentration range of 10-10,000 pg/mL. To confirm PMA in equine urine, LC retention time, diagnostic product ions (m/z 188, m/z 281 and m/z 323) and product ion ratio were used as the criteria. The lowest concentration for confirmatory analysis was validated at 50 pg/mL. The method was applied to measure the PMA concentrations in equine urine following intravenous administration of fentanyl to a research horse and has confirmed the presence of PMA in post-race urine samples. This method is a valuable addition to the arsenal of equine doping control methods to combat illegal doping and protect racehorse health.

Automated identification of unknown doping agents in confiscation samples by flow-injection mass spectrometry and mass spectral library searches.

Rapid and accurate identification of unknown compounds within suspicious samples confiscated for sports doping control and law enforcement drug testing is critical, but such analyses are often conducted manually and can be time-consuming. Here, we report a methodology for automated identification of unknown substances in confiscation samples by rapid automatic flow-injection analysis on a liquid chromatography coupled to high-resolution mass spectrometry system and identifying unknown compounds with Compound Discoverer software. The developed methodology was validated by comparing the automated identification results with those obtained from manual syringe-infusion experiments and manual tandem mass spectral library searches. The automated methodology resulted in far higher throughput and remarkably shorter turnaround time for analysis when compared with manual procedures and, in most cases, yielded more compounds. As this is the first such report to the authors' knowledge, this methodology may potentially transform analysis of confiscated samples in sports doping control and law enforcement drug testing.

Pharmacokinetics of glaucine after intravenous and oral administrations and detection of systemic aporphine alkaloids after ingestion of tulip poplar shavings in horses.

Glaucine, an aporphine alkaloid with anti-tussive, anti-inflammatory, and anti-nociceptive properties, has been identified in post-race samples from racehorses. To investigate pharmacokinetics of glaucine in horses, a three-way crossover study of intravenous and oral glaucine (0.1 mg/kg) and orally administered tulip poplar shavings (50 g shavings = 0.001 mg/kg glaucine) was performed in six horses. A two-compartment model best described IV administration with alpha ( t 1 / 2 α ) and beta ( t 1 / 2 ß ) half-life lives of 0.3 (0.1-0.7) and 3.1 (2.4-7.8) h, respectively. The area under the curve ( AUC 0 ∞ iv ) was 45.4 (34.7-52.3) h*ng/ml, and the volume of distribution of the central (Vdc ) and peripheral (Vdp ) compartments was 2.7 (1.3-4.6) and 4.9 (4.3-8.2) L/kg, respectively. A one compartment model best described the oral administration of glaucine with absorption ( t 1 / 2 ka ) and elimination ( t 1 / 2 kel ) half-lives of 0.09 (0.05-0.15) and 0.7 (0.6-0.8) h, respectively. The area under the curve ( AUC 0 ∞ PO ) was 15.1 (8.0-19.5) h·ng/ml. Bioavailability following oral administration was 17%-48%. Following ingestion of shavings, glaucine and liriodenine were detectable in plasma for up to 16 and 48 h, respectively. Glaucine was quantifiable briefly in the urine from two horses. Liriodenine was quantifiable in urine for 12-20 h in four horses and for 48 h in two horses. The presence of liriodenine indicates ingestion of tulip poplar tree parts, however, does not rule out co-administration of purified glaucine in horses.

Pharmacokinetics and pharmacodynamics of oral and intravenous metoprolol tartrate in clinically healthy horses.

Cardiac drugs with defined pharmacological parameters in horses are limited. The objective of this study was to characterize the pharmacokinetic properties and cardiovascular effects of intravenous and oral metoprolol tartrate (MET) in horses. In a 2-period randomized cross-over design, MET was administered IV (0.04 mg/kg) and PO (6 mg/kg) once to six healthy adult horses. Horses were monitored via continuous telemetry and non-invasive blood pressure (NIBP). Blood samples were serially collected for 72 h post-administration, and concentrations were determined by LC-MS/MS. Pharmacokinetics were modeled using a 3-compartment model and non-linear least squares regression. Median (range) MET concentration was 110 (40.1-197) ng/ml collected 1 min (0.0167 h) after a bolus IV administration. Maximum concentration (Cmax ) after PO administration was 2135 (1590-4170) ng/ml at 0.5 (0.25-0.5) hours. Oral bioavailability was 54% (17-100%). Median apparent volume of distribution was 0.39 (0.17-0.58) l/kg, clearance was 12.63 (11.41-18.94) ml/kg/min, and elimination half-life was 21.1 (7.46-34.36) minutes. No clinically relevant effects of IV or PO metoprolol were noted on cardiac rhythm or NIBP. Sweating was the most common side effect. The metoprolol doses used in this study achieve plasma concentrations reported to achieve ß-blockade in humans.