Morphine, pethidine and buprenorphine disposition in the cat

Abstract

Pharmacokinetics of morphine, buprenorphine and pethidine were determined in 10 cats. Six cats received morphine (0.2 mg/kg) intravenously and four intramuscularly. Five received buprenorphine (0.01 mg/kg) intravenously and six intramuscularly. Six received pethidine (5 mg/kg) intramuscularly. Jugular venous blood samples were collected at time points to 24 h, and plasma morphine concentrations were measured by high performance liquid chromatograpy (HPLC), buprenorphine by radioimmunoassay (RIA) and pethidine by gas chromatography. Our data for morphine show elimination half-life (t1/2el) 76.3 min intravenous (i.v.) and 93.6 min intramuscular (i.m.); mean residence time (MRT) 105.0 and 120.5 min; clearance (Clp) 24.1 and 13.9 mL/kg/min; and volume of distribution (V(dss)) 2.6 and 1.7 L/kg, respectively. Comparable data for buprenorphine are t1/2el 416.8 and 380.2 min; MRT 417.6 and 409.8 min; Clp 16.7 and 23.7 mL/kg/min; and V(dss) 7.1 and 8.9 L/kg. For i.m. pethidine, t1/2el 216.4 min; MRT 307.5 min; Clp 20.8 mL/kg/min and V(dss) 5.2 L/kg. For i.m. dosing, the tmax for morphine, buprenorphine and pethidine were 15, 3 and 10 min, respectively. The pharmacokinetics of the three opioids in cats are broadly comparable with those of the dog, although there is a suggestion that the cat may clear morphine more slowly.

Avaliação da analgesia pós-operatória da metadona, da cetamina ou da sua associação em gatas submetidas a ovariossalpingo-histerectomia

“…Com 12 e 24 horas de avaliação nenhum dos animais recebeu resgate; ou seja, até oito horas pós-operatória, os animais necessitavam de analgesia complementar, pois, nas próximas avaliações, que foram após quatro e 16 horas depois do último resgate, não havia mais efeito da morfina ou apenas efeito residual. Segundo Taylor et al (2001), em felinos, a meiavida plasmática da morfina pela via intramuscular é de 93,6 minutos, com intervalo posológico de aproximadamente quatro a seis horas. Esse período é prolongado devido à deficiência de glicuroniltransferase nessa espécie (Otero, 2005).…”

Avaliação da buprenorfina pelas vias intravenosa ou intramuscular em cães anestesiados pelo desfluorano

“…Este efeito foi considerado significativo estatisticamente no GI, com queda mais acentuada 30 minutos após a administração do opióide (M3). Esta redução pode estar relacionada à maior biodisponibilidade do fármaco (TAYLOR et al, 2001) Com relação à PAP se evidenciou apenas um discreto declínio do seu valor inicial, após a administração do opióide com maior ênfase no GI, sem significado clínico ou estatístico. Tal redução é compatível com aquela observada na PAM (Tabela 1), pois a PAP tem estreita relação com a pressão arterial sistêmica, sendo 6 a 8 vezes mais baixa que esta (FRANCHINI, 1999).…”

Pain management in cat

“…Αυτό ίσως να οφείλεται στο γεγονός ότι κατά το μεταβολισμό του μορίου της μορφίνης στη γά τα παράγεται πολΰ μικρή ποσότητα του αναλγητικώς δραστικοΰ μεταβολίτη M-6-G, ο οποίος, στον άνθρωπο, συμμετέχει σημαντικά στο αναλγητικό αποτέλεσμα (Murthy et al 2002). Γενικά, σε σΰγκριση με το σκΰ λο, στη γάτα η μορφίνη μεταβολίζεται βραδΰτερα, με αποτέλεσμα να παραμένει για σχετικά μεγαλύτερο χρονικό διάστημα στον οργανισμό του ζώου μετά από μία έγχυση (Taylor et al 2001). Επίσης, στο ζωικό αυ τό είδος μπορεί να προκαλέσει υπερθερμία (Wagner 2002).…”

“…Όμως, η διάρκεια της δράσης αυτής είναι μικρή, περίπου 1,5 ώρα (Lascelles et al1995). Η ενδοφλέβια χορήγηση αποφεύγεται, κα θώς μπορεί να προκαλέσει υπόταση ή/και διέγερση (Taylor et al 2001). Έχει γρήγορη έναρξη δράσης με τά από ενδομυϊκή χορήγηση και ίσως γι' αυτό, χορη γούμενη μετεγχειρητικούς, έχει αποτελέσει μέτρο σύ γκρισης για πολλά άλλα φάρμακα, σε ό,τι αφορά στην προκαλούμενη αναλγησία (Lascelles et al 1995, Taylor et al2001.…”