Naloxone gastrointestinal effects

The answer is c. (Hardman, p 527. Katzung, p 516.) Naloxone is a pure opioid antagonist at the (1, K, and 5 receptors. j,-receptor stimulation causes analgesia, euphoria, decreased gastrointestinal (Gl) activity, miosis, and respiratory depression. K-receptor stimulation causes analgesia, dysphoria, and psychotomimetic effects. 5-receptor stimulation is not fully understood in humans, but is associated with analgesia and antinociception for thermal stimuli. 

It is a pure antagonist and chemically related to naloxone. It is more potent than naloxone and because of its longer duration of action, it can be used as maintenance drug for morphine addicts. It has no euphoric effect and no physical dependence liability. It is effective orally. It is also claimed to be beneficial in decreasing craving for alcohol in alcoholics. Side effects include gastrointestinal disturbances and muscular pain. 

Artru A A 1990 Hypocapnia and diazepam reverse and midazolam or fentanyl attenuates ketamine induced Increase of cerebral blood volume and/or cerebrospinal fluid pressure. In Domino E F (ed) Status of ketamine in anesthesiology. NPP Books, Ann Arbor, Ml, p. 119 Aurich C, Aurich J E, Klug E 1993 Naloxone affects gastrointestinal functions and behaviour in horses. Deutsche Tierarztiiche Wochenschrift 100 314-315 Ballard S, Shults T, Kownacki A A et al 1982 The pharmacokinetics, pharmacological responses and behavioral effects of acepromazine in the horse. 

Basic and advanced life-support measures should be performed as necessary. Gastrointestinal decontamination procedures should be considered for substantial recent ingestions. Activated charcoal will adsorb codeine. Patients with respiratory or CNS depression can be treated with intravenous boluses of naloxone. A continuous naloxone infusion may be necessary if the toxic effects of codeine persist longer than the duration of action of naloxone. 

Opioid antagonists (Table 7.4), predominantly naloxone, are used clinically to reverse the effects of opiates in overdose or postoperative sedation. Naltrexone, which has oral bioavailability, is used for the treatment of narcotic addiction and alcohol dependence. As discussed below (Section 2.2.2.1), peripherally selective antagonists are being evaluated for treatment of constipation and other gastrointestinal side effects associated with opioid agonist use. 

Gastrointestinal constipation and nausea are common. Nausea may be treated with antiemetics, and frequently improves with ongoing therapy. Virtually all patients taking opioids become constipated and do not become tolerant to this side effect. Activation of mu receptors in the gastrointestinal tract slows peristalsis, which promotes further absorption of water and electrolytes in the colon. Patients should be treated prophylactically with stool softeners and/ or laxatives. There is an oral oxycodone/naloxone prolonged-release tablet in clinical trials to counteract opioid-induced constipation, which is often debilitating. 

Akkawi R, Eksborg S, Andersson A, Lundeberg S, Bartocci M. Effect of oral naloxone hydrochloride on gastrointestinal transit in premature infants treated with morphine. Acta Paediatr 2009 98 (3) 442-7. 

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