Review of the rectal use of opioids

The rectal route for the administration of opioid analgesics is often forgotten by physicians seeking alternatives to the oral route. This article reviews the physiology of rectal drug absorption and such data as exists on the different opioids that have been administered by this route. Conventional fatty-based suppositories have a place in the management of chronic pain but the variability in dissolution and drug absorption limit their usefulness. Recently, sustained release vehicles have become available that offer the prospect of the attainment of steady analgesic drug concentrations with once or twice daily dosing. Early studies with the morphine hydrogel suppository suggest that it may be capable of fulfilling this prospect. Their inherent safety, as dose-dumping is impossible, will make them suitable for use in the home.