{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,16]],"date-time":"2026-05-16T09:14:37Z","timestamp":1778922877452,"version":"3.51.4"},"reference-count":31,"publisher":"American Veterinary Medical Association (AVMA)","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2007,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n<jats:p><jats:bold>Objective<\/jats:bold>\u2014To assess the pharmacokinetics and pharmacodynamics of morphine in llamas.<\/jats:p>\n<jats:p><jats:bold>Animals<\/jats:bold>\u20146 healthy adult llamas.<\/jats:p>\n<jats:p><jats:bold>Procedures<\/jats:bold>\u2014Llamas received morphine sulfate in a randomized crossover design. In phase 1, they received IV or IM administration of morphine at 0.05 or 0.5 mg\/kg, respectively; in phase 2, they received IV administration of morphine at 0.05, 0.25, or 0.5 mg\/kg. Plasma morphine and morphine-6-glucuronide concentrations were determined by validated methods. Body temperature, heart rate, respiratory rate, sedation, and analgesia were assessed and compared with plasma concentrations by regression analysis.<\/jats:p>\n<jats:p><jats:bold>Results<\/jats:bold>\u2014Total body clearance was similar between IV administration of morphine sulfate at 0.25 and 0.5 mg\/kg (mean \u00b1 SD, 25.3 \u00b1 6.9 mL\/min\/kg and 27.3 \u00b1 5.9 mL\/min\/kg, respectively), and linearity was demonstrated between these doses. Bioavailability of morphine following IM administration at 0.5 mg\/kg was 120 \u00b1 30%. Body temperature and sedation increased as the dose of morphine administered increased. Heart rate was unaffected by varying doses. Respiratory rate decreased as dose increased. Analgesia was difficult to assess as a result of high individual variability. Intravenous administration of morphine at 0.25 mg\/kg provided the most consistent increase in tolerance to electric stimulation. Pharmacodynamic modeling revealed a sigmoidal relationship between plasma concentration and sedation score.<\/jats:p>\n<jats:p><jats:bold>Conclusions and Clinical Relevance<\/jats:bold>\u2014Morphine was characterized by a large apparent volume of distribution and high systemic clearance in llamas. A prolonged half-life was observed with IM injection. Intravenous administration of morphine sulfate at 0.25 mg\/kg every 4 hours is suggested for further study.<\/jats:p>","DOI":"10.2460\/ajvr.68.1.25","type":"journal-article","created":{"date-parts":[[2007,1,2]],"date-time":"2007-01-02T19:30:22Z","timestamp":1167766222000},"page":"25-34","source":"Crossref","is-referenced-by-count":22,"title":["Pharmacokinetics and pharmacodynamics of morphine in llamas"],"prefix":"10.2460","volume":"68","author":[{"given":"Samantha R.","family":"Uhrig","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mark G.","family":"Papich","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Butch","family":"KuKanich","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Khursheed R.","family":"Mama","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ann E.","family":"Wagner","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Phillip L.","family":"Chapman","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter W.","family":"Hellyer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1272","reference":[{"key":"ref1","series-title":"J Am Vet Med Assoc","first-page":"1441","article-title":"Evaluation of lidocaine, xylazine, and a combination of lidocaine and xylazine for epidural analgesia in llamas","volume":"203","author":"Grubb","year":"1993"},{"key":"ref2","series-title":"Medicine and surgery of South American camelids","author":"Fowler","year":"250"},{"key":"ref3","series-title":"J Am Vet Med Assoc","doi-asserted-by":"publisher","first-page":"1263","DOI":"10.2460\/javma.2001.219.1263","article-title":"Pharmacokinetics and pharmacodynamics of butorphanol in llamas after intravenous and intramuscular administration","volume":"219","author":"Carroll","year":"2001"},{"key":"ref4","series-title":"Compend Contin Educ Pract Vet","first-page":"181","article-title":"Pain. 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