{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T22:34:03Z","timestamp":1778279643375,"version":"3.51.4"},"reference-count":17,"publisher":"American Veterinary Medical Association (AVMA)","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["javma"],"published-print":{"date-parts":[[2013,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n<jats:p><jats:bold>Objective<\/jats:bold>\u2014To determine the pharmacokinetics of morphine after IM administration in a clinical population of horses.<\/jats:p>\n<jats:p><jats:bold>Design<\/jats:bold>\u2014Prospective clinical study.<\/jats:p>\n<jats:p><jats:bold>Animals<\/jats:bold>\u201477 horses.<\/jats:p>\n<jats:p><jats:bold>Procedures<\/jats:bold>\u2014Morphine sulfate (0.1 mg\/kg [0.045 mg\/lb], IM) was administered to horses, and blood samples were obtained at predetermined time points. Plasma morphine concentrations were measured via liquid chromatography and mass spectrometry. In preliminary investigations, samples were obtained from 2 healthy horses at 12 time points (up to 12 hours after drug administration) and analyzed via 2-stage pharmacokinetic analysis. In the clinical phase, blood samples were obtained from 75 hospitalized horses at various times (total, 2 to 3 samples\/horse) up to 9 hours after drug administration, and data were analyzed via a na\u00efve pooled pharmacokinetic model.<\/jats:p>\n<jats:p><jats:bold>Results<\/jats:bold>\u2014In the clinical phase, the apparent terminal half-life (t<jats:sub>\u00bd<\/jats:sub>) of morphine was approximately 1.5 hours, volume of distribution per bioavailability was approximately 4.5 L\/kg, and clearance per bioavailability was approximately 35 mL\/kg\/min. Peak plasma concentration in na\u00efve pooled analysis was 21.6 ng\/mL and occurred approximately 4 minutes after administration. Morphine concentrations were below the limit of quantification \u2264 7 hours after administration in 74 horses. Adverse effects attributed to morphine administration were uncommon and considered mild.<\/jats:p>\n<jats:p><jats:bold>Conclusions and Clinical Relevance<\/jats:bold>\u2014The short t<jats:sub>\u00bd<\/jats:sub> of morphine in horses suggested frequent administration may be needed to maintain targeted plasma concentrations. Variations in plasma concentrations suggested optimal dosages may differ among horses. The drug was well tolerated at the described dose, but patients receiving morphine should be monitored carefully.<\/jats:p>","DOI":"10.2460\/javma.243.1.105","type":"journal-article","created":{"date-parts":[[2013,6,20]],"date-time":"2013-06-20T16:04:51Z","timestamp":1371744291000},"page":"105-112","source":"Crossref","is-referenced-by-count":16,"title":["Pharmacokinetics of intramuscularly administered morphine in horses"],"prefix":"10.2460","volume":"243","author":[{"given":"Elizabeth P.","family":"Devine","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Butch","family":"KuKanich","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Warren L.","family":"Beard","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1272","reference":[{"key":"ref1","series-title":"Equine Vet J","doi-asserted-by":"publisher","first-page":"229","DOI":"10.1111\/j.2042-3306.1978.tb02267.x","article-title":"The effect of some anti-diarrhoeal drugs on intestinal transit and faecal excretion of water and electrolytes in the horse","volume":"10","author":"Alexander","year":"1978"},{"key":"ref2","series-title":"Vet Anaesth Analg","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1046\/j.1467-2995.2003.00092.x","article-title":"Problems associated with perioperative morphine in horses: a retrospective case analysis","volume":"30","author":"Mircica","year":"2003"},{"key":"ref3","series-title":"J Vet Pharmacol Ther","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1111\/j.1365-2885.2010.01183.x","article-title":"Population pharmacokinetics of mavacoxib in osteoarthritic dogs","volume":"34","author":"Cox","year":"2011"},{"key":"ref4","series-title":"J Vet Pharmacol Ther","doi-asserted-by":"publisher","first-page":"283","DOI":"10.1111\/j.1365-2885.2004.00591.x","article-title":"Population pharmacokinetics of marbofloxacin in horses: preliminary analysis","volume":"27","author":"Peyrou","year":"2004"},{"key":"ref5","series-title":"Am J Vet Res","first-page":"217","article-title":"Effects of butorphanol, flunixin, levorphanol, morphine, and xylazine in ponies","volume":"45","author":"Kalpravidh","year":"1984"},{"key":"ref6","series-title":"Can J Comp Med","first-page":"138","article-title":"Electromyoenterography during normal gastro-intestinal activity, painful or non-painful colic and morphine analgesia, in the horse","volume":"36","author":"Phaneuf","year":"1972"},{"key":"ref7","series-title":"Am J Vet Res","doi-asserted-by":"publisher","first-page":"992","DOI":"10.2460\/ajvr.67.6.992","article-title":"Evaluation of the effects of the opioid agonist morphine on gastrointestinal tract function in horses","volume":"67","author":"Boscan","year":"2006"},{"key":"ref8","series-title":"Vet Anaesth Analg","doi-asserted-by":"publisher","first-page":"22","DOI":"10.1111\/j.1467-2995.2007.00350.x","article-title":"The effects of morphine on the recovery of horses from halothane anaesthesia","volume":"35","author":"Clark","year":"2008"},{"key":"ref9","series-title":"Am J Vet Res","first-page":"870","article-title":"Pharmacokinetics and protein binding of morphine in horses","volume":"44","author":"Combie","year":"1983"},{"key":"ref10","series-title":"Am J Vet Res","doi-asserted-by":"publisher","first-page":"166","DOI":"10.2460\/ajvr.2003.64.166","article-title":"Interactions of morphine and isoflurane in horses","volume":"64","author":"Steffey","year":"2003"},{"key":"ref11","series-title":"J Equine Med Surg","first-page":"377","article-title":"Pharmacology of narcotic analgesics in the horse IV. Dose and time response relationships for behavioral-responses to morphine, meperidine, pentazocine, anileridine, methadone, and hydromorphone","volume":"3","author":"Combie","year":"1979"},{"key":"ref12","series-title":"Acta Anaesthesiol Scand","doi-asserted-by":"publisher","first-page":"725","DOI":"10.1034\/j.1399-6576.2003.00138.x","article-title":"Influences on serum concentrations of morphine, M6G and M3G during routine clinical drug monitoring: a prospective survey in 300 adult cancer patients","volume":"47","author":"Klepstad","year":"2003"},{"key":"ref13","series-title":"Clin Pharmacokinet","doi-asserted-by":"publisher","first-page":"266","DOI":"10.2165\/00003088-198207030-00006","article-title":"Patient-controlled analgesic therapy, part IV: pharmacokinetics and analgesic plasma concentrations of morphine","volume":"7","author":"Dahlstr\u00f6m","year":"1982"},{"key":"ref14","series-title":"Equine Vet Educ","doi-asserted-by":"publisher","first-page":"37","DOI":"10.2746\/095777308X382669","article-title":"Managing severe hoof pain in a horse using multimodal analgesia and a modified composite pain score","volume":"21","author":"Dutton","year":"2009"},{"key":"ref15","series-title":"Clin Pharmacol Ther","doi-asserted-by":"publisher","first-page":"66","DOI":"10.1016\/S0009-9236(99)70123-2","article-title":"Analgesic efficacy of a combination of hydrocodone with ibuprofen in postoperative pain","volume":"65","author":"Wideman","year":"1999"},{"key":"ref16","series-title":"Br J Anaesth","doi-asserted-by":"publisher","first-page":"292","DOI":"10.1093\/bja\/aeq406","article-title":"Paracetamol and selective and non-selective non-steroidal anti-inflammatory drugs for the reduction in morphine-related side-effects after major surgery: a systematic review","volume":"106","author":"Maund","year":"2011"},{"key":"ref17","series-title":"Am J Vet Res","first-page":"1762","article-title":"Cardiopulmonary and gastrointestinal motility effects of xylazine\/ketamine-induced anesthesia in horses previously treated with glycopyrrolate","volume":"57","author":"Singh","year":"1996"}],"container-title":["Journal of the American Veterinary Medical Association"],"original-title":[],"link":[{"URL":"https:\/\/avmajournals.avma.org\/view\/journals\/javma\/243\/1\/javma.243.1.105.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/avmajournals.avma.org\/downloadpdf\/journals\/javma\/243\/1\/javma.243.1.105.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/avmajournals.avma.org\/downloadpdf\/journals\/javma\/243\/1\/javma.243.1.105.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,3,7]],"date-time":"2025-03-07T11:39:10Z","timestamp":1741347550000},"score":1,"resource":{"primary":{"URL":"https:\/\/avmajournals.avma.org\/view\/journals\/javma\/243\/1\/javma.243.1.105.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2013,7,1]]},"references-count":17,"journal-issue":{"issue":"1"},"URL":"https:\/\/doi.org\/10.2460\/javma.243.1.105","relation":{},"ISSN":["0003-1488"],"issn-type":[{"value":"0003-1488","type":"print"}],"subject":[],"published":{"date-parts":[[2013,7,1]]}}}