The conversion challenge: from intrathecal to oral morphine

Abstract

Numerous articles have described the methodologies used and outcomes achieved with the intrathecal (IT) administration of morphine for pain. However, only one case report has been published that describes converting a patient's IT morphine to an oral regimen. This case report describes the experience of converting a patient's IT morphine to oral morphine and discusses the scarcity of published data to validate suggested equianalgesic intraspinal morphine recommendations. The calculated equianalgesic oral to IT ratio in this case was 12:1. This is substantially lower than the 300:1 ratio published by Krames and the 90:1 ratio employed by a commercially available software program for calculating equianalgesic opioid doses. We recommend caution when applying existing guidelines for conversion of morphine from an IT to an oral regimen.