Opioid alternate administration routes

If disturbances of gastrointestinal function prevent the use of oral sustained-release morphine, the fentanyl transdermal system (fentanyl patch) can be used over long periods. Furthermore, buccal transmucosal fentanyl can be used for short episodes of breakthrough pain (see Alternative Routes of Administration). Administration of strong opioids by nasal insufflation has been shown to be efficacious, and nasal preparations are now available in some countries. Approval of such formulations in the USA is growing. In addition, stimulant drugs such as the amphetamines have been shown to enhance the analgesic actions of the opioids and thus may be very useful adjuncts in the patient with chronic pain. 

Previous reports of opioid withdrawal on single exposure have been described after the administration of intramuscular morphine in healthy individuals. This case suggests that opioid dependence can occur after acute exposure to morphine by the epidural route too. An alternative explanation (28) is that the stress of labor may have led to increased endogenous opioid activity, particularly B-endorphin, and that the antagonistic effect of naloxone on the endogenous opioid system contributed to the clinical effects in this patient. Moreover, the authors pointed out that many symptoms characteristic of the classic opioid withdrawal sjmdrome were not present in the patient. 

The availability of new routes of administration have led to increased utility and decreased opioid adverse drug reaction risk. Epidural and intrathecal administration through spinal catheters produces adequate regional analgesia at relatively low total doses compared with intravenous or oral routes. As such, spinal administration can thus minimize somnolence, nausea, vomiting, and respiratory depression associated with these medications. Other alternative routes include intranasal administration of butorphanol, and rectal and transdermal administration of fentanyl [28]. Availability of such options provides not only a decreased risk of adverse reactions, but also more comfortable measures for patients who would otherwise require continued intravenous administration, or for those who are unable to receive oral medication [28,29]. 

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