The pharmacokinetics of methocarbamol in the thoroughbred race horse

Cunningham, Francesca; Fisher, J.; Bevelle, C.; Cwik, Michael; Jensen, R. C.

doi:10.1111/j.1365-2885.1992.tb00992.x

Cited by 5 publications

(14 citation statements)

References 9 publications

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“…() reported the systemic clearance after an 11.2 (±0.979) mg/kg intravenous dose to six horses. In the previous studies, the systemic clearance after a dose of 17.6 mg/kg was 8.55 (±1.52) mL/min/kg (Muir et al ., ) and that after a dose of 11.2 mg/kg was 7.58 (±2.30) mL/min/kg (Cunningham et al ., ). These values compare well with the current study mean (SD) of 8.90 (±1.77) mL/min/kg.…”

Section: Discussionmentioning

confidence: 97%

“…The lower bioavailability reported by Cunningham et al . () may be due in part to the manner in which the MCBL tablets were administered in the current study. The tablets were crushed, mixed with water to form a slurry, administered by a nasogastric tube, and the tube was then rinsed with water to assure maximal delivery of the oral dose.…”

Section: Discussionmentioning

confidence: 98%

“…Cunningham et al . () also investigated oral pharmacokinetics of MCBL in horses after a 5‐g dose. Bioavailability was lower and less variable than reported in the current study with a mean (SD) of 36.3 (4.7)%.…”

Section: Discussionmentioning

confidence: 99%

“…These values compare well with the current study mean (SD) of 8.90 (±1.77) mL/min/kg. Similarly, the volume of distribution at steady‐state was 0.724 (±0.094) L/kg (Muir et al ., ) and 0.812 (±0.235) L/kg (Cunningham et al ., ). These values compare favorably with the current study values of 1.05 (±0.09) L/kg.…”

Section: Discussionmentioning

confidence: 99%

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The pharmacokinetics of methocarbamol and guaifenesin after single intravenous and multiple‐dose oral administration of methocarbamol in the horse

Rumpler

Colahan

Samś

2013

Vet Pharm & Therapeutics

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A simple LC/MSMS method has been developed and fully validated to determine concentrations and characterize the concentration vs. time course of methocarbamol (MCBL) and guaifenesin (GGE) in plasma after a single intravenous dose and multiple oral dose administrations of MCBL to conditioned Thoroughbred horses. The plasma concentration-time profiles for MCBL after a single intravenous dose of 15 mg/kg of MCBL were best described by a three-compartment model. Mean extrapolated peak (C0 ) plasma concentrations were 23.2 (± 5.93) μg/mL. Terminal half-life, volume of distribution at steady-state, mean residence time, and systemic clearance were characterized by a median (range) of 2.96 (2.46-4.71) h, 1.05 (0.943-1.21) L/kg, 1.98 (1.45-2.51) h, and 8.99 (6.68-10.8) mL/min/kg, respectively. Oral dose of MCBL was characterized by a median (range) terminal half-life, mean transit time, mean absorption time, and apparent oral clearance of 2.89 (2.21-4.88) h, 2.67 (1.80-2.87) h, 0.410 (0.350-0.770) h, and 16.5 (13.0-20) mL/min/kg. Bioavailability of orally administered MCBL was characterized by a median (range) of 54.4 (43.2-72.8)%. Guaifenesin plasma concentrations were below the limit of detection in all samples collected after the single intravenous dose of MCBL whereas they were detected for up to 24 h after the last dose of the multiple-dose oral regimen. This difference may be attributed to first-pass metabolism of MCBL to GGE after oral administration and may provide a means of differentiating the two routes of administration.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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The pharmacokinetics of methocarbamol and guaifenesin after single intravenous and multiple‐dose oral administration of methocarbamol in the horse

Rumpler

Colahan

Samś

2013

Vet Pharm & Therapeutics

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“…The pharmacokinetics of MCBL have been described previously (Muir et al ., , ; Cunningham et al ., ; Rumpler et al ., ). An elimination half‐life of 1.68 (Cunningham et al ., ) and 2.89 h (Rumpler et al ., ) has been reported previously for oral administration and 2.96 h for intravenous administration (Rumpler et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetics of methocarbamol and phenylbutazone in exercised Thoroughbred horses

Knych

Stanley

Seminoff

et al. 2016

Vet Pharm & Therapeutics

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Methocarbamol (MCBL) is commonly used in performance horses for the treatment of skeletal muscle disorders. Current regulatory recommendations for show horses and racehorses are based on a single oral dose of 5 g, although doses in excess of this are often administered. The goal of the current study was to characterize the disposition of MCBL following higher dose administration and administration in combination with another commonly used drug in performance horses, phenylbutazone (PBZ). Exercised Thoroughbred horses were administered various doses of MCBL as a sole agent and MCBL in combination with PBZ. Blood samples were collected at various times, concentrations of MCBL and PBZ measured using LC-MS/MS and pharmacokinetic parameters calculated using compartmental analysis. Following administration of 15 g of MCBL, either as part of a single- or multiple-dose regimen, a number of horses exceeded the Association of Racing Commissioners International and the United States Equestrian Federation's recommended regulatory threshold at the recommended withdrawal time. There was not a significant difference between horses that received only MCBL and those that received MCBL and PBZ. Results of the current study support an extended withdrawal guideline when doses in excess of 5 g are administered.

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Anesthetic and Analgesic Adjunctive Drugs

Pang

2015

Veterinary Anesthesia and Analgesia

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The pharmacokinetics of methocarbamol in the thoroughbred race horse

Cited by 5 publications

References 9 publications

The pharmacokinetics of methocarbamol and guaifenesin after single intravenous and multiple‐dose oral administration of methocarbamol in the horse

The pharmacokinetics of methocarbamol and guaifenesin after single intravenous and multiple‐dose oral administration of methocarbamol in the horse

Pharmacokinetics of methocarbamol and phenylbutazone in exercised Thoroughbred horses

Anesthetic and Analgesic Adjunctive Drugs

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