Successful Use of Oral Methadone after Failure of Intravenous Morphine and Ketamine

Abstract

We describe an opioid-tolerant patient with severe acute pain which was unrelieved by morphine and ketamine via intravenous patient-controlled analgesia, but almost totally relieved by methadone. In the previous 24 hours, 509 mg of intravenous morphine and 769 mg of ketamine had been used and this was replaced by 200 mg of oral methadone. This implies that the success of methadone in morphine tolerant patients chiefly involves factors other than its role as an N-methyl-D-aspartate receptor antagonist, and that methadone should be considered as a replacement for morphine when the N-methyl-D-aspartate antagonist ketamine has proved ineffective.