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Song D, Jusko WJ. Across‐species meta‐analysis of dexamethasone pharmacokinetics utilizing allometric and scaling modeling approaches. Biopharm Drug Dispos 2021; 42:191-203. [DOI: 10.1002/bdd.2266] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 01/15/2021] [Accepted: 01/27/2021] [Indexed: 12/15/2022]
Affiliation(s)
- Dawei Song
- Department of Pharmaceutical Sciences School of Pharmacy and Pharmaceutical Sciences State University of New York at Buffalo Buffalo New York USA
| | - William J Jusko
- Department of Pharmaceutical Sciences School of Pharmacy and Pharmaceutical Sciences State University of New York at Buffalo Buffalo New York USA
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Held F, Ekstrand C, Cvijovic M, Gabrielsson J, Jirstrand M. Modelling of oscillatory cortisol response in horses using a Bayesian population approach for evaluation of dexamethasone suppression test protocols. J Pharmacokinet Pharmacodyn 2019; 46:75-87. [PMID: 30673914 PMCID: PMC6394511 DOI: 10.1007/s10928-018-09617-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/31/2018] [Indexed: 11/12/2022]
Abstract
Cortisol is a steroid hormone relevant to immune function in horses and other species and shows a circadian rhythm. The glucocorticoid dexamethasone suppresses cortisol in horses. Pituitary pars intermedia dysfunction (PPID) is a disease in which the cortisol suppression mechanism through dexamethasone is challenged. Overnight dexamethasone suppression test (DST) protocols are used to test the functioning of this mechanism and to establish a diagnosis for PPID. However, existing DST protocols have been recognized to perform poorly in previous experimental studies, often indicating presence of PPID in healthy horses. This study uses a pharmacokinetic/pharmacodynamic (PK/PD) modelling approach to analyse the oscillatory cortisol response and its interaction with dexamethasone. Two existing DST protocols were then scrutinized using model simulations with particular focus on their ability to avoid false positive outcomes. Using a Bayesian population approach allowed for quantification of uncertainty and enabled predictions for a broader population of horses than the underlying sample. Dose selection and sampling time point were both determined to have large influence on the number of false positives. Advice on pitfalls in test protocols and directions for possible improvement of DST protocols were given. The presented methodology is also easily extended to other clinical test protocols.
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Affiliation(s)
- Felix Held
- Fraunhofer-Chalmers Centre, Chalmers Science Park, Gothenburg, Sweden.
- Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden.
| | - Carl Ekstrand
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Marija Cvijovic
- Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden
| | - Johan Gabrielsson
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Mats Jirstrand
- Fraunhofer-Chalmers Centre, Chalmers Science Park, Gothenburg, Sweden
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Lavoie JP, Leclere M, Rodrigues N, Lemos KR, Bourzac C, Lefebvre-Lavoie J, Beauchamp G, Albrecht B. Efficacy of inhaled budesonide for the treatment of severe equine asthma. Equine Vet J 2018; 51:401-407. [PMID: 30203854 PMCID: PMC6585971 DOI: 10.1111/evj.13018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 09/06/2018] [Indexed: 01/22/2023]
Abstract
Background Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs. Objectives To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma. Study design Experimental studies in horses with naturally occurring asthma with cross‐over, randomised, blinded experimental designs. Methods In Study 1, budesonide (1800 μg twice daily) administered using a novel Respimat® based inhaler was compared to i.v. dexamethasone (0.04 mg/kg). In Study 2, 3 doses of budesonide (450, 900, and 1800 μg) were compared to oral dexamethasone (0.066 mg/kg). Lung function, bronchoalveolar fluid cytology (Study 1), CBC, serum chemistry, and serum cortisol and adrenocorticotropic hormone (ACTH) values were evaluated. Results In Study 1, there was a marked and significant improvement in the lung function of all horses treated with budesonide and dexamethasone. Neutrophil percentages in bronchoalveolar fluid decreased in all horses treated with dexamethasone and in four of six horses treated with budesonide. Serum cortisol and blood ACTH concentrations decreased with both treatments. In Study 2, there was a significant improvement in the lung function with all dosages of budesonide, and the effects of higher dosages were comparable to those of dexamethasone. Dexamethasone and budesonide at the two higher dosages induced a significant decrease of cortisol concentrations. Main limitations The Respimat® based inhaler is not currently commercially available. Conclusions Administration of budesonide with the Respimat® based inhaler provided dose‐dependent relief of airway obstruction in horses with severe asthma, but also a suppression of serum cortisol.
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Affiliation(s)
- J P Lavoie
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - M Leclere
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - N Rodrigues
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - K R Lemos
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - C Bourzac
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - J Lefebvre-Lavoie
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - G Beauchamp
- Department of Veterinary Biomedicine, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - B Albrecht
- Boehringer Ingelheim Vetmedica GmbH, Ingelheim am Rhein, Germany
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Haspel AD, Giguère S, Hart KA, Berghaus LJ, Davis JL. Bioavailability and tolerability of nebulised dexamethasone sodium phosphate in adult horses. Equine Vet J 2017; 50:85-90. [PMID: 28719014 DOI: 10.1111/evj.12724] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
BACKGROUND Nebulisation of the injectable dexamethasone sodium phosphate (DSP) would offer an inexpensive way of delivering a potent corticosteroid directly to the lungs of horses with asthma. However, this approach would be advantageous only if systemic absorption is minimal and if the preservatives present in the formulation do not induce airway inflammation. OBJECTIVE To investigate the bioavailability of nebulised DSP and determine whether it induces airway inflammation or hypothalamic-pituitary-adrenal (HPA) axis suppression in healthy adult horses. STUDY DESIGN Randomised crossover experiment. METHODS Dexamethasone sodium phosphate was administered to six healthy adult horses at a dose of 5 mg q. 24 h for 5 days via nebulised, or intravenous (i.v.) routes. Plasma dexamethasone concentrations were measured by UPLC/MS-MS to calculate bioavailability. Cytological examination of bronchoalveolar fluid was performed at baseline and after the last dose of DSP. A validated chemiluminescent immunoassay was used to measure basal serum cortisol concentrations. RESULTS After nebulisation to adult horses, dexamethasone had a mean (±s.d.) maximum plasma concentration of 0.774 ± 0.215 ng/mL and systemic bioavailability of 4.3 ± 1.2%. Regardless of route of administration, there was a significant decrease in the percentage of neutrophils in bronchoalveolar lavage fluid over time. During i.v. administration, basal serum cortisol concentration decreased significantly from baseline to Day 3 and remained low on Day 5. In contrast, basal serum cortisol concentration did not change significantly during administration via nebulisation. MAIN LIMITATIONS Small sample size and short period of drug administration. CONCLUSIONS Dexamethasone sodium phosphate administered via nebulisation had minimal systemic bioavailability and did not induce lower airway inflammation or HPA axis suppression in healthy horses.
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Affiliation(s)
- A D Haspel
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - S Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - K A Hart
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - L J Berghaus
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - J L Davis
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Blacksburg, Virginia, USA
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Leclere M. Corticosteroids and Immune Suppressive Therapies in Horses. Vet Clin North Am Equine Pract 2017; 33:17-27. [PMID: 28325178 DOI: 10.1016/j.cveq.2016.11.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Immune suppressive therapies target exaggerated and deleterious responses of the immune system. Triggered by exogenous or endogenous factors, these improper responses can lead to immune or inflammatory manifestations, such as urticaria, equine asthma, or autoimmune and immune-mediated diseases. Glucocorticoids are the most commonly used immune suppressive drugs and the only ones supported by robust evidence of clinical efficacy in equine medicine. In some conditions, combining glucocorticoids with other pharmacologic and nonpharmacologic treatments, such as azathioprine, antihistamine, bronchodilators, environmental management, or desensitization, can help to decrease dosages and associated side effects.
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Affiliation(s)
- Mathilde Leclere
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Quebec J2S 7C6, Canada.
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Cuming RS, Groover ES, Wooldridge AA, Caldwell FJ. Review of glucocorticoid therapy in horses. Part 1: Pharmacology. EQUINE VET EDUC 2016. [DOI: 10.1111/eve.12555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R. S. Cuming
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - E. S. Groover
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - A. A. Wooldridge
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - F. J. Caldwell
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
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Ekstrand C, Ingvast-Larsson C, Olsén L, Hedeland M, Bondesson U, Gabrielsson J. A quantitative approach to analysing cortisol response in the horse. J Vet Pharmacol Ther 2015; 39:255-63. [PMID: 26542753 DOI: 10.1111/jvp.12276] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 09/26/2015] [Indexed: 11/28/2022]
Abstract
The cortisol response to glucocorticoid intervention has, in spite of several studies in horses, not been fully characterized with regard to the determinants of onset, intensity and duration of response. Therefore, dexamethasone and cortisol response data were collected in a study applying a constant rate infusion regimen of dexamethasone (0.17, 1.7 and 17 μg/kg) to six Standardbreds. Plasma was analysed for dexamethasone and cortisol concentrations using UHPLC-MS/MS. Dexamethasone displayed linear kinetics within the concentration range studied. A turnover model of oscillatory behaviour accurately mimicked cortisol data. The mean baseline concentration range was 34-57 μg/L, the fractional turnover rate 0.47-1.5 1/h, the amplitude parameter 6.8-24 μg/L, the maximum inhibitory capacity 0.77-0.97, the drug potency 6-65 ng/L and the sigmoidicity factor 0.7-30. This analysis provided a better understanding of the time course of the cortisol response in horses. This includes baseline variability within and between horses and determinants of the equilibrium concentration-response relationship. The analysis also challenged a protocol for a dexamethasone suppression test design and indicated future improvement to increase the predictability of the test.
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Affiliation(s)
- C Ekstrand
- Department of Biomedical Sciences and Veterinary Public Health, Division of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - C Ingvast-Larsson
- Department of Biomedical Sciences and Veterinary Public Health, Division of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - L Olsén
- Department of Biomedical Sciences and Veterinary Public Health, Division of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - M Hedeland
- Department of Chemistry, Environment and Feed Hygiene, National Veterinary Institute (SVA), Uppsala, Sweden.,Department of Medicinal Chemistry, Division of Analytical Pharmaceutical Chemistry, Uppsala University, Uppsala, Sweden
| | - U Bondesson
- Department of Chemistry, Environment and Feed Hygiene, National Veterinary Institute (SVA), Uppsala, Sweden.,Department of Medicinal Chemistry, Division of Analytical Pharmaceutical Chemistry, Uppsala University, Uppsala, Sweden
| | - J Gabrielsson
- Department of Biomedical Sciences and Veterinary Public Health, Division of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Ekstrand C, Bondesson U, Gabrielsson J, Hedeland M, Kallings P, Olsén L, Ingvast-Larsson C. Plasma concentration-dependent suppression of endogenous hydrocortisone in the horse after intramuscular administration of dexamethasone-21-isonicotinate. J Vet Pharmacol Ther 2014; 38:235-42. [DOI: 10.1111/jvp.12175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 09/15/2014] [Indexed: 11/28/2022]
Affiliation(s)
- C. Ekstrand
- Division of Pharmacology and Toxicology; Department of Biomedical Sciences and Veterinary Public Health; Swedish University of Agricultural Sciences; Uppsala Sweden
| | - U. Bondesson
- Department of Chemistry, Environment and Feed Hygiene; National Veterinary Institute; Uppsala Sweden
- Division of Analytical Pharmaceutical Chemistry; Department of Medicinal Chemistry; Uppsala University; Uppsala Sweden
| | - J. Gabrielsson
- Division of Pharmacology and Toxicology; Department of Biomedical Sciences and Veterinary Public Health; Swedish University of Agricultural Sciences; Uppsala Sweden
| | - M. Hedeland
- Department of Chemistry, Environment and Feed Hygiene; National Veterinary Institute; Uppsala Sweden
- Division of Analytical Pharmaceutical Chemistry; Department of Medicinal Chemistry; Uppsala University; Uppsala Sweden
| | - P. Kallings
- Swedish-Norwegian Foundation for Equine Research; Stockholm Sweden
- Swedish Trotting Association; Stockholm Sweden
| | - L. Olsén
- Division of Pharmacology and Toxicology; Department of Biomedical Sciences and Veterinary Public Health; Swedish University of Agricultural Sciences; Uppsala Sweden
| | - C. Ingvast-Larsson
- Division of Pharmacology and Toxicology; Department of Biomedical Sciences and Veterinary Public Health; Swedish University of Agricultural Sciences; Uppsala Sweden
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SOMA LR, UBOH CE, LIU Y, LI X, ROBINSON MA, BOSTON RC, COLAHAN PT. Pharmacokinetics of dexamethasone following intra-articular, intravenous, intramuscular, and oral administration in horses and its effects on endogenous hydrocortisone. J Vet Pharmacol Ther 2012; 36:181-91. [DOI: 10.1111/j.1365-2885.2012.01412.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Grady JA, Davis EG, Kukanich B, Sherck AB. Pharmacokinetics and pharmacodynamics of dexamethasone after oral administration in apparently healthy horses. Am J Vet Res 2010; 71:831-9. [PMID: 20594087 DOI: 10.2460/ajvr.71.7.831] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess pharmacokinetic and pharmacodynamic properties of dexamethasone administered PO as a solution or powder, compared with properties of dexamethasone solution administered IV, in apparently healthy horses. ANIMALS 6 adult horses. PROCEDURES Serum cortisol concentration for each horse was determined before each treatment (baseline values). Dexamethasone (0.05 mg/kg) was administered PO (in solution or powdered form) or IV (solution) to horses from which feed had or had not been withheld (unfed and fed horses, respectively). Each horse received all 6 treatments in random order at 2-week intervals; PO and IV administrations of dexamethasone were accompanied by IV or PO sham treatments, respectively. Plasma dexamethasone and serum cortisol concentrations were assessed at predetermined intervals. RESULTS Maximum plasma dexamethasone concentration after PO administration of powdered dexamethasone in unfed horses was significantly higher than the maximum plasma concentration after PO administration of dexamethasone solution in unfed or fed horses. Mean bioavailability of dexamethasone ranged from 28% to 66% but was not significantly different among horses receiving either formulation PO in the unfed or fed state. After dexamethasone treatment PO or IV, serum cortisol concentrations were significantly less than baseline at 1 to 72 hours in unfed horses and at 2 to 48 hours in fed horses. CONCLUSIONS AND CLINICAL RELEVANCE PO or IV administration of dexamethasone resulted in suppression of cortisol secretion in unfed and fed adult horses; the magnitude of suppression did not differ among treatment groups, and serum cortisol concentrations returned to baseline after 48 to 72 hours.
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Affiliation(s)
- Jason A Grady
- Veterinary Medical Teaching Hospital, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
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Leclere M, Lefebvre-Lavoie J, Beauchamp G, Lavoie JP. Efficacy of oral prednisolone and dexamethasone in horses with recurrent airway obstruction in the presence of continuous antigen exposure. Equine Vet J 2010; 42:316-21. [PMID: 20525049 DOI: 10.1111/j.2042-3306.2009.00022.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY Orally administered prednisolone and dexamethasone are used commonly in the treatment of recurrent airway obstruction (RAO) in horses. However, the efficacy of prednisolone in improving pulmonary function during continuous antigen exposure has not been evaluated critically and there is little evidence supporting the efficacy of low-dose oral dexamethasone in the same conditions. HYPOTHESIS Oral prednisolone and dexamethasone improve pulmonary function in RAO under conditions of continuous antigen exposure, and dexamethasone is more effective than prednisolone at commonly used dosages. METHODS Using a randomised crossover design, prednisolone (2 mg/kg bwt) and dexamethasone (0.05 mg/kg bwt) were administered per os, s.i.d. for 7 days, to 7 horses during clinical exacerbation of the disease. Maximal difference in transpulmonary pressure (DeltaP(L)), lung resistance (R(L)) and elastance (E(L)) were measured before and after 3 and 7 days of treatment. RESULTS Prednisolone and dexamethasone improved pulmonary function significantly. However, the improvement was of greater magnitude after 3 and 7 days of treatment with dexamethasone compared to prednisolone. Also, after 7 days of treatment with dexamethasone, DeltaP(L) and R(L) were not different from values obtained when horses were on pasture, while all 3 pulmonary function parameters remained different from pasture values after prednisolone treatment. CONCLUSIONS Both corticosteroids improve pulmonary function, in spite of continuous antigen exposure. However, oral dexamethasone at 0.05 mg/kg bwt is more effective than prednisolone at 2 mg/kg bwt in the treatment of RAO. POTENTIAL RELEVANCE Prednisolone was shown, for the first time, to our knowledge, to improve the pulmonary function of horses with RAO in the presence of continuous antigen exposure. This study also demonstrates the efficacy of low-dose oral dexamethasone in reversing airway obstruction in these conditions.
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Affiliation(s)
- M Leclere
- Clinical Sciences Department, Faculté de Médecine Vétérinaire, Université de Montréal. 3200 Sicotte Saint-Hyacinthe, J2S 7C6, Quebec, Canada
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FERRIS RA, McCUE PM. The effects of dexamethasone and prednisolone on pituitary and ovarian function in the mare. Equine Vet J 2010; 42:438-43. [DOI: 10.1111/j.2042-3306.2010.00034.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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AUTHIE EC, GARCIA P, POPOT MA, TOUTAIN PL, DOUCET M. Effect of an endurance-like exercise on the disposition and detection time of phenylbutazone and dexamethasone in the horse: Application to medication control. Equine Vet J 2010; 42:240-7. [DOI: 10.1111/j.2042-3306.2010.00029.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Haffner JC, Eiler H, Hoffman RM, Fecteau KA, Oliver JW. Effect of a single dose of dexamethasone on glucose homeostasis in healthy horses by using the combined intravenous glucose and insulin test1. J Anim Sci 2009; 87:131-5. [DOI: 10.2527/jas.2008-1179] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Soma LR, Uboh CE, Luo Y, Guan F, Moate PJ, Boston RC. Pharmacokinetics of dexamethasone with pharmacokinetic/pharmacodynamic model of the effect of dexamethasone on endogenous hydrocortisone and cortisone in the horse. J Vet Pharmacol Ther 2005; 28:71-80. [PMID: 15720518 DOI: 10.1111/j.1365-2885.2004.00632.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A compartmental model was used to describe the pharmacokinetics of dexamethasone (DXM) and changes in the plasma concentration of endogenous cortisone (COR) and hydrocortisone (HYD) following intravenous (i.v.) administration of DXM (0.05 mg/kg) in horses. Quantification of DXM, COR and HYD in equine plasma was achieved using liquid chromatography interfaced with triple spray quadrupole quantum tandem mass spectrometry (LC/TSQ-MS/MS). The median alpha (t(1/2alpha)), beta (t(1/2beta)), and gamma (t(1/2gamma)) half-lives were 0.33, 2.2, and 10.7 h respectively. The area under the DXM plasma concentration curve (AUC) was 113.5 ng.h/mL. At 72 h post-DXM administration, the plasma concentration of DXM in all horses was below the level of quantification (100 pg/mL). The baseline plasma concentration of COR was 3.5 +/- 0.69 ng/mL and declined significantly (P < 0.02) to 2.9 +/- 0.86 ng/mL at 1 h. The nadir in COR plasma concentration was 0.65 +/- 0.12 ng/mL at 28.8 +/- 9.0 h, and the DXM plasma concentration was 0.19 +/- 0.13 ng/mL. COR concentration returned to baseline at 96 h. Baseline plasma concentration of HYD was 58.8 +/- 11.7 ng/mL and declined significantly (P < 0.001) to 41.1 +/- 14.9 ng/mL at 1 h following DXM administration but recovered to baseline at 96 h. The sensitivity of LC/TSQ-MS/MS allowed complete description of the pharmacokinetics of DXM and its effect on plasma concentrations of both COR and HYD.
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Affiliation(s)
- L R Soma
- School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA.
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Abstract
Terminal plasma half-life is the time required to divide the plasma concentration by two after reaching pseudo-equilibrium, and not the time required to eliminate half the administered dose. When the process of absorption is not a limiting factor, half-life is a hybrid parameter controlled by plasma clearance and extent of distribution. In contrast, when the process of absorption is a limiting factor, the terminal half-life reflects rate and extent of absorption and not the elimination process (flip-flop pharmacokinetics). The terminal half-life is especially relevant to multiple dosing regimens, because it controls the degree of drug accumulation, concentration fluctuations and the time taken to reach equilibrium.
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Affiliation(s)
- P L Toutain
- UMR 181 Physiopathologie et Toxicologie Expérimentales INRA/ENVT, Ecole Nationale Vétérinaire de Toulouse, Toulouse cedex 03, France.
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Cornelisse CJ, Robinson NE, Berney CEA, Kobe CA, Boruta DT, Derksen FJ. Efficacy of oral and intravenous dexamethasone in horses with recurrent airway obstruction. Equine Vet J 2004; 36:426-30. [PMID: 15253084 DOI: 10.2746/0425164044868413] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Although the efficacy of dexamethasone for the treatment of recurrent airway obstruction (RAO) has been documented, the speed of onset of effect and duration of action are unknown, as is the efficacy of orally administered dexamethasone with or without fasting. OBJECTIVES To document the time of onset of effect and duration of action of a dexamethasone solution i.v. or orally with and without fasting. METHODS Protocol 1 used 8 RAO-affected horses with airway obstruction in a crossover design experiment that compared the effect of i.v. saline and dexamethasone (0.1 mg/kg bwt) on pulmonary function over 4 h. Protocol 2 used 6 similar horses to compare, in a crossover design, the effects of dexamethasone i.v. (0.1 mg/kg bwt), dexamethasone per os (0.164 mg/kg bwt) with and without prior fasting, and dexamethasone per os (0.082 mg/kg) with fasting. RESULTS Dexamethasone i.v. caused significant improvement in lung function within 2 h with a peak effect at 4-6 h. Dexamethasone per os was effective within 6 h with peak effect at 24 h at a dose of 0.164 mg/kg bwt prior to feeding. The duration of effect was, for all dexamethasone treatments, statistically significant for 30 h when compared to saline and tended to have a longer duration of effect when used orally. Dexamethasone per os at a dose of 0.164 mg/kg bwt to fed horses had mean effects comparable to dexamethasone at a dose of 0.082 mg/kg bwt per os given to fasted horses, indicating that feeding decreases bioavailability. CONCLUSIONS Dexamethasone administered i.v. has a rapid onset of action in RAO-affected horses. Oral administration of a bioequivalent dose of the same solution to fasted horses is as effective as i.v. administration and tends to have longer duration of action. Fasting horses before oral administration of dexamethasone improves the efficacy of treatment. POTENTIAL RELEVANCE Oral administration to fasted horses of a dexamethasone solution intended for i.v. use provides an effective treatment for RAO-affected animals.
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Affiliation(s)
- C J Cornelisse
- Pulmonary Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824-1314, USA
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Al Katheeri NA, Wasfi IA, Lambert M, Saeed A. Lack of gender effect on the pharmacokinetics and pharmacodynamics of dexamethasone in the camel after intravenous administration. Res Vet Sci 2004; 77:73-81. [PMID: 15120956 DOI: 10.1016/j.rvsc.2004.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2004] [Indexed: 11/26/2022]
Abstract
The pharmacokinetics and pharmacodynamics of dexamethasone were studied in six male and six female camels after a single intravenous dose (0.05 mgkg(-1) body weight) of dexamethasone. The pharmacokinetic parameters of the two-compartment pharmacokinetic model for female and male camels, respectively (mean+/-SEM) were as follows: terminal elimination half-lives were 8.02+/-1.15 and 7.33+/-0.80 h, total body clearances were 95.5+/-16.0 and 124.5+/-11.9 ml h(-1) per kg, volumes of distribution at steady state were 0.72+/-0.08 and 0.87+/-0.14 litre kg(-1), and the volumes of the central compartment were 0.12+/-0.02 and 0.17+/-0.02 litre kg(-1). There was no significant difference in any pharmacokinetic parameter between female and male camels. Pharmacodynamic effects were evaluated by measuring endogenous plasma cortisol, circulating lymphocytes and neutrophils numbers and were analysed using indirect pharmacokinetic/pharmacodynamic models. The estimated IC50 of dexamethasone for cortisol and lymphocytes for female and male camels were 3.74+/-0.99 and 2.28+/-1.09 and 2.63+/-0.71 and 2.41+/-0.79 ng ml(-1), respectively. The EC50 for neutrophils for female and male camels were 24.5+/-5.83 and 20.2+/-3.82 ng ml(-1), respectively. There was no significant difference in any pharmacodynamic parameter between female and male camels. Dexamethasone in urine could be detected for 4-5 days by enzyme-linked immunosorbent assay and for 3-4 days by liquid chromatography/mass spectrometry after an intravenous dose of 0.05 mg kg(-1) body weight.
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Affiliation(s)
- Nawal A Al Katheeri
- Forensic Science Laboratory, Camelracing Laboratory, P.O. Box 253, Abu Dhabi, United Arab Emirates
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