Effects of epidural naloxone on pruritus induced by epidural morphine: a randomized controlled trial

Naloxone added to bupivacaine or bupivacaine–fentanyl prolongs motor and sensory block during supraclavicular brachial plexus blockade: a randomized clinical trial

“…Other data suggest that an ultra‐low dose of naloxone augmented the anti‐nociceptive effect of morphine by enhancing the reuptake of excitatory amino acids from the synaptic cleft . Human studies from 2001 and 2007 imply that applying low doses of naloxone intrathecally could reduce opioid side effects and enhance analgesia . Results in an earlier study suggested that naloxone in low doses could release endorphins, or probably relocate endorphins from receptor sites .…”

Pruritus in two horses following epidurally administered morphine

“…However, high doses of naloxone could potentially reverse existing analgesia. Jeon et al (2005) evaluated the efficacy of an epidural combination of naloxone and morphine administered to 58 pregnant women undergoing caesarean section. They concluded that this combination was effective in reducing the incidence and severity of pruritus.…”

Naloxone prolongs cutaneous nociceptive block by lidocaine in rats

“…Cumulative evidence shows that opioids induce inhibitory and/or excitatory modulation of action potentials in sensory neurons [32]. In human studies, a low dose of epidural naloxone enhances analgesia as well as reduces opioid side effects [33][34][35]. Interestingly, a larger dose of naloxone elicited hyperalgesia, whereas a small dose resulted in paradoxical analgesia [36][37][38].…”