Effects of maropitant, acepromazine, and electroacupuncture on vomiting associated with administration of morphine in dogs

• Localización: JAVMA: Journal of the American Veterinary Medical Association, ISSN-e 0003-1488, Vol. 244, Nº. 7, 2014, págs. 820-829
• Idioma: inglés
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• Resumen

  • Objective�To evaluate effects of maropitant, acepromazine, and electroacupuncture on morphine-related signs of nausea and vomiting in dogs and assess sedative effects of the treatments.

    Design�Randomized controlled clinical trial.

    Animals�222 dogs.

    Procedures�Dogs received 1 of 6 treatments: injection of saline (0.9% NaCl) solution, maropitant citrate, or acepromazine maleate or electroacupuncture treatment at 1 acupoint, 5 acupoints, or a sham acupoint. Morphine was administered after 20 minutes of electroacupuncture treatment or 20 minutes after injectable treatment. Vomiting and retching events and signs of nausea and sedation were recorded.

    Results�Incidence of vomiting and retching was significantly lower in the maropitant (14/37 [37.8%]) group than in the saline solution (28/37 [75.7%]) and sham-acupoint electroacupuncture (32/37 [86.5%]) groups. The number of vomiting and retching events in the maropitant (21), acepromazine (38), 1-acupoint (35), and 5-acupoint (34) groups was significantly lower than in the saline solution (88) and sham-acupoint electroacupuncture (109) groups. Incidence of signs of nausea was significantly lower in the acepromazine group (3/37 [8.1%]) than in the sham-acupoint group (15/37 [40.5%]). Mean nausea scores for the saline solution, maropitant, and sham-acupoint electroacupuncture groups increased significantly after morphine administration, whereas those for the acepromazine, 1-acupoint electroacupuncture, and 5-acupoint electroacupuncture groups did not. Mean sedation scores after morphine administration were significantly higher in dogs that received acepromazine than in dogs that received saline solution, maropitant, and sham-acupoint electroacupuncture treatment.

    Conclusions and Clinical Relevance�Maropitant treatment was associated with a lower incidence of vomiting and retching, compared with control treatments, and acepromazine and electroacupuncture appeared to prevent an increase in severity of nausea following morphine administration in dogs.

    Opioids have been used to provide consistent and effective pain relief in animals for many years and are commonly used for pain management in veterinary practice, especially for the management of postoperative pain in dogs.1,2 However, opioids have been associated with some adverse effects in dogs.3,4 Nausea and vomiting occur frequently in dogs after administration of morphine,a hydromorphone, and oxymorphone.4�6 Vomiting may occur after IV, IM, or epidural administration of morphine.6�8 The emetic effects of morphine usually occur within 5 minutes after IM administration at a dose of 0.5 mg/kg (0.23 mg/lb).4 One study7 revealed a high incidence of vomiting (23/38 [61%]) after IM administration of a 0.5 mg of morphine/kg in dogs; in the same study, a 1.0 mg/kg (0.45 mg/lb) dose of morphine caused 12 of 13 dogs to vomit. In another study9 of 30 dogs, 9 (30%) and 24 (80%) dogs vomited following IM administration of morphine at doses of 0.22 and 1.10 mg/kg (0.1 and 0.5 mg/lb), respectively. In a more recent study,10 5 of 8 dogs vomited after receiving a 1.0 mg/kg dose of morphine IM. Vomiting can result in aspiration of gastric contents, esophagitis and resultant stricture, tension on suture lines, and increased intracranial and intraocular pressure, which may prolong hospitalization.11,12 Under normal circumstances, the gag reflex and coughing will prevent aspiration; however, these protective reflexes are compromised in animals that are sedated or anesthetized. Additionally, profuse vomiting may lead to dehydration, electrolyte depletion, and disturbances in acid-base balance.

    Maropitant citrate is a neurokinin-1 receptor antagonist developed specifically to prevent nausea and vomiting in dogs and cats.13 Maropitant prevents acute vomiting associated with a wide range of clinical conditions, such as parvoviral enteritis, gastroenteritis resulting from dietary indiscretion, and pancreatitis as well as acute or delayed vomiting in canine cancer patients undergoing chemotherapy.14�16 Maropitant is effective in preventing nausea and vomiting induced by hydromorphone in dogs.17 To our knowledge, there are no large-scale studies of its effects on morphine-related nausea and vomiting in dogs.

    Acepromazine maleate, a phenothiazine tranquilizer, has antidopaminergic and antihistaminergic properties at low doses in the chemoreceptor trigger zone and anticholinergic effects at higher doses in the emetic center of the brain.18 It has been shown to decrease the incidence of vomiting caused by opioids in dogs.4,19 Acepromazine administered 15 minutes prior to morphine lowered the incidence of vomiting by 50% (2/8 vs 12/16), compared with the incidence in dogs that received acepromazine 15 minutes after opioid administration.4 Acepromazine can cause hypotension because of its vasodilatory properties and therefore may be contraindicated in some patients.19,20 Drugs such as methylnaltrexone, haloperidol, droperidol, and ondansetron are reported to decrease morphine-related vomiting but are not commonly used in veterinary medicine owing to very limited experience, lack of research or clinical studies, and expense.21�23 Acupuncture, a branch of traditional Chinese veterinary medicine, may have potential use as an antiemetic treatment in veterinary practice.24 Electroacupuncture is a form of acupuncture modality in which a small electric current is passed between pairs of acupuncture needles. In a pilot study,25 electroacupuncture at the pericardium-6 acupoint was shown to decrease the number of vomiting episodes induced by morphine in ferrets by approximately 40% (mean, 5.6 ± 2.2 episodes vs 9.8 ± 0.6 episodes). Electroacupuncture at the pericardium-6 acupoint significantly suppressed retrograde peristaltic contractions and subsequently lowered the number of vasopressin-induced retching and vomiting episodes in dogs by 34.5 ± 7.9% (mean number of episodes, 4.9 ± 0.8 vs 1.8 ± 0.2 [retching] and 5.1 ± 0.7 vs 1.6 ± 0.2 [vomiting]).26,27 Acupuncture at acupoints such as pericardium-6, stomach-36, bladder-20, bladder-21, liver-13, or conception vessel-12 has been reported to effectively prevent vomiting in dogs.27�30 Among these acupoints, pericardium-6 is the most frequently studied antiemetic acupoint.31,32 According to traditional Chinese veterinary medicine, pericardium-6 is located on the pericardium meridian, which is used in the treatment of nausea, vomiting, anxiety, seizures, and cardiac arrhythmias.33 Although the physiologic mechanisms by which stimulation of acupoints affects nausea and vomiting remain largely unknown, increasing evidence from clinical trials suggests that stimulation of pericardium-6 is efficacious in preventing nausea and vomiting associated with surgery and chemotherapy in human patients.34�38 To our knowledge, the effect of electroacupuncture has not been extensively studied in dogs for the prevention of nausea and vomiting associated with opioid administration.

    The purpose of the study reported here was to assess the effects of maropitant, acepromazine, and electroacupuncture on vomiting, retching, and signs of nausea following morphine administration in dogs. We hypothesized that treatment with maropitant, acepromazine, and electroacupuncture before morphine administration would prevent or decrease the incidence of vomiting and retching and eliminate or decrease the severity of signs of nausea associated with this treatment. We also hypothesized that electroacupuncture would result in a greater degree of sedation, compared with dogs administered a saline (0.9% NaCl) solution, maropitant, or sham-acupoint electroacupuncture treatment.