Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis

ABSTRACT Background Phenazopyridine is used for ancillary pain management in the treatment of goats with obstructive urolithiasis. However, there are no published studies on the pharmacokinetics, safety, or efficacy of phenazopyridine in goats. Hypothesis/Objectives Determine the pharmacokinetic par...

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Main Authors: Sienna L. Mitman, Danielle A. Mzyk, Blanca E. Camacho, R. McAlister Council‐Troche, Jennifer Davis, Derek M. Foster, Jennifer Halleran
Format: Article
Language:English
Published: Wiley 2025-07-01
Series:Journal of Veterinary Internal Medicine
Subjects:
Online Access:https://doi.org/10.1111/jvim.70167
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author Sienna L. Mitman
Danielle A. Mzyk
Blanca E. Camacho
R. McAlister Council‐Troche
Jennifer Davis
Derek M. Foster
Jennifer Halleran
author_facet Sienna L. Mitman
Danielle A. Mzyk
Blanca E. Camacho
R. McAlister Council‐Troche
Jennifer Davis
Derek M. Foster
Jennifer Halleran
author_sort Sienna L. Mitman
collection DOAJ
description ABSTRACT Background Phenazopyridine is used for ancillary pain management in the treatment of goats with obstructive urolithiasis. However, there are no published studies on the pharmacokinetics, safety, or efficacy of phenazopyridine in goats. Hypothesis/Objectives Determine the pharmacokinetic parameters of phenazopyridine after oral administration in goats with obstructive urolithiasis after tube cystostomy surgery. Animals Six male goats, ages 3 months to 4 years. Methods Prospective, observational study. Goats presenting to a veterinary institution diagnosed with obstructive urolithiasis underwent a tube cystostomy surgery. After surgery, phenazopyridine (4 mg/kg PO q12h) was administered. Plasma and urine samples were collected at predetermined intervals, and the concentration of phenazopyridine and clinically relevant metabolites was determined using ultra high‐performance liquid chromatography with mass spectrometry. The pharmacokinetic parameters were determined using non‐compartmental analysis. Results The harmonic mean terminal elimination plasma half‐life (T1/2), geometric mean maximum plasma concentration (Cmax), and area under the curve (AUC) were 0.5 h (0.22–1.57 h), 263.4 ng/mL (137.35–1047.88 ng/mL), and 0.69 h*ng/mL (0.10–2.99 h*ng/mL), respectively for phenazopyridine. The concentration of phenazopyridine in urine samples was below the limit of assay detection (1.5 ng/mL) in all but one sample. Conclusions and Clinical Importance Phenazopyridine was rapidly eliminated from plasma and did not concentrate at detectable levels in the urine after oral administration.
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spelling doaj-art-c86d4c14526a4c89853df1f4425c60da2025-08-20T03:09:35ZengWileyJournal of Veterinary Internal Medicine0891-66401939-16762025-07-01394n/an/a10.1111/jvim.70167Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive UrolithiasisSienna L. Mitman0Danielle A. Mzyk1Blanca E. Camacho2R. McAlister Council‐Troche3Jennifer Davis4Derek M. Foster5Jennifer Halleran6North Carolina State University, College of Veterinary Medicine Raleigh North Carolina USANorth Carolina State University, College of Veterinary Medicine, Department of Population Health and Pathobiology Raleigh North Carolina USANorth Carolina State University, College of Veterinary Medicine Raleigh North Carolina USAVirginia‐Maryland Regional College of Veterinary Medicine, Department of Biomedical Sciences and Pathobiology Blacksburg Virginia USAVirginia‐Maryland Regional College of Veterinary Medicine, Department of Biomedical Sciences and Pathobiology Blacksburg Virginia USANorth Carolina State University, College of Veterinary Medicine, Department of Population Health and Pathobiology Raleigh North Carolina USANorth Carolina State University, College of Veterinary Medicine, Department of Population Health and Pathobiology Raleigh North Carolina USAABSTRACT Background Phenazopyridine is used for ancillary pain management in the treatment of goats with obstructive urolithiasis. However, there are no published studies on the pharmacokinetics, safety, or efficacy of phenazopyridine in goats. Hypothesis/Objectives Determine the pharmacokinetic parameters of phenazopyridine after oral administration in goats with obstructive urolithiasis after tube cystostomy surgery. Animals Six male goats, ages 3 months to 4 years. Methods Prospective, observational study. Goats presenting to a veterinary institution diagnosed with obstructive urolithiasis underwent a tube cystostomy surgery. After surgery, phenazopyridine (4 mg/kg PO q12h) was administered. Plasma and urine samples were collected at predetermined intervals, and the concentration of phenazopyridine and clinically relevant metabolites was determined using ultra high‐performance liquid chromatography with mass spectrometry. The pharmacokinetic parameters were determined using non‐compartmental analysis. Results The harmonic mean terminal elimination plasma half‐life (T1/2), geometric mean maximum plasma concentration (Cmax), and area under the curve (AUC) were 0.5 h (0.22–1.57 h), 263.4 ng/mL (137.35–1047.88 ng/mL), and 0.69 h*ng/mL (0.10–2.99 h*ng/mL), respectively for phenazopyridine. The concentration of phenazopyridine in urine samples was below the limit of assay detection (1.5 ng/mL) in all but one sample. Conclusions and Clinical Importance Phenazopyridine was rapidly eliminated from plasma and did not concentrate at detectable levels in the urine after oral administration.https://doi.org/10.1111/jvim.70167analgesiacaprinepharmacologyurolithiasis
spellingShingle Sienna L. Mitman
Danielle A. Mzyk
Blanca E. Camacho
R. McAlister Council‐Troche
Jennifer Davis
Derek M. Foster
Jennifer Halleran
Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
Journal of Veterinary Internal Medicine
analgesia
caprine
pharmacology
urolithiasis
title Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
title_full Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
title_fullStr Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
title_full_unstemmed Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
title_short Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis
title_sort pharmacokinetics of orally administered phenazopyridine in goats with obstructive urolithiasis
topic analgesia
caprine
pharmacology
urolithiasis
url https://doi.org/10.1111/jvim.70167
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