K R Mama1, K Grimsrud, T Snell, S Stanley. 1. Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
Abstract
REASONS FOR PERFORMING STUDY: Detomidine hydrochloride is used to provide sedation, muscle relaxation and analgesia in horses, but a lack of information pertaining to plasma concentration has limited the ability to correlate drug concentration with effect. OBJECTIVES: To build on previous information and assess detomidine for i.v. and i.m. use in horses by simultaneously assessing plasma drug concentrations, physiological parameters and behavioural characteristics. HYPOTHESIS: Systemic effects would be seen following i.m. and i.v. detomidine administration and these effects would be positively correlated with plasma drug concentrations. METHODS: Behavioural (e.g. head position) and physiological (e.g. heart rate) responses were recorded at fixed time points from 4 min to 24 h after i.m. or i.v. detomidine (30 microg/kg bwt) administration to 8 horses. Route of administration was assigned using a balanced crossover design. Blood was sampled at predetermined time points from 0.5 min to 48 h post administration for subsequent detomidine concentration measurements using liquid chromatography-mass spectrometry. Data were summarised as mean +/- s.d. for subsequent analysis of variance for repeated measures. RESULTS: Plasma detomidine concentration peaked earlier (1.5 min vs. 1.5 h) and was significantly higher (105.4 +/- 71.6 ng/ml vs. 6.9 +/- 1.4 ng/ml) after i.v. vs. i.m. administration. Physiological and behavioural changes were of a greater magnitude and observed at earlier time points for i.v. vs. i.m. groups. For example, head position decreased from an average of 116 cm in both groups to a low value 35 +/- 23 cm from the ground 10 min following i.v. detomidine and to 64 +/- 24 cm 60 min after i.m. detomidine. Changes in heart rate followed a similar pattern; low value of 17 beats/min 10 min after i.v. administration and 29 beats/min 30 min after i.m. administration. CONCLUSIONS: Plasma drug concentration and measured effects were correlated positively and varied with route of administration following a single dose of detomidine. POTENTIAL RELEVANCE: Results support a significant influence of route of administration on desirable and undesirable drug effects that influence case management.
REASONS FOR PERFORMING STUDY: Detomidine hydrochloride is used to provide sedation, muscle relaxation and analgesia in horses, but a lack of information pertaining to plasma concentration has limited the ability to correlate drug concentration with effect. OBJECTIVES: To build on previous information and assess detomidine for i.v. and i.m. use in horses by simultaneously assessing plasma drug concentrations, physiological parameters and behavioural characteristics. HYPOTHESIS: Systemic effects would be seen following i.m. and i.v. detomidine administration and these effects would be positively correlated with plasma drug concentrations. METHODS: Behavioural (e.g. head position) and physiological (e.g. heart rate) responses were recorded at fixed time points from 4 min to 24 h after i.m. or i.v. detomidine (30 microg/kg bwt) administration to 8 horses. Route of administration was assigned using a balanced crossover design. Blood was sampled at predetermined time points from 0.5 min to 48 h post administration for subsequent detomidine concentration measurements using liquid chromatography-mass spectrometry. Data were summarised as mean +/- s.d. for subsequent analysis of variance for repeated measures. RESULTS: Plasma detomidine concentration peaked earlier (1.5 min vs. 1.5 h) and was significantly higher (105.4 +/- 71.6 ng/ml vs. 6.9 +/- 1.4 ng/ml) after i.v. vs. i.m. administration. Physiological and behavioural changes were of a greater magnitude and observed at earlier time points for i.v. vs. i.m. groups. For example, head position decreased from an average of 116 cm in both groups to a low value 35 +/- 23 cm from the ground 10 min following i.v. detomidine and to 64 +/- 24 cm 60 min after i.m. detomidine. Changes in heart rate followed a similar pattern; low value of 17 beats/min 10 min after i.v. administration and 29 beats/min 30 min after i.m. administration. CONCLUSIONS: Plasma drug concentration and measured effects were correlated positively and varied with route of administration following a single dose of detomidine. POTENTIAL RELEVANCE: Results support a significant influence of route of administration on desirable and undesirable drug effects that influence case management.
Authors: K N Grimsrud; S Ait-Oudhia; B P Durbin-Johnson; D M Rocke; K R Mama; M L Rezende; S D Stanley; W J Jusko Journal: J Vet Pharmacol Ther Date: 2014-07-29 Impact factor: 1.786
Authors: Alice Rodrigues de Oliveira; Miguel Gozalo-Marcilla; Simone Katja Ringer; Stijn Schauvliege; Mariana Werneck Fonseca; Pedro Henrique Esteves Trindade; José Nicolau Prospero Puoli Filho; Stelio Pacca Loureiro Luna Journal: Front Vet Sci Date: 2021-02-16