Continuous ketamine infusion for the management of opioid-induced hyperalgesia following amputation.

We discuss the use of an inpatient multi-day continuous intravenous ketamine infusion for the treatment of opioid-induced hyperalgesia (OIH) and high fentanyl requirements in the case of a patient with a background of fibromyalgia/central sensitisation syndrome who underwent a complicated post-operative course following a right below-knee amputation for high-grade myxoid fibrosarcoma. The patient was successfully tapered off a total fentanyl patch dose of 162 mcg/hour every 72 hours (morphine equivalent dose of 389 mg/day) to short-acting hydromorphone 2 mg orally two times per day as needed (equivalent of 8 mg morphine sustained-release twice per day) during a 2-week admission with only mild withdrawal symptoms. We discuss the pharmacology of ketamine and its possible application in the treatment of OIH.

Identification and synthesis of norhydromorphone, and determination of antinociceptive activities in the rat formalin test.

The main objective of this paper is to report the identification and synthesis of norhydromorphone, a novel metabolite of hydromorphone, and its antinociceptive activities when tested in the formalin test as compared to other known analgesics. In addition, we are reporting for the first time the lack of antinociceptive activities of hydromorphone-3-glucuronide, dihydromorphine-3-glucuronide and dihydroisomorphine-3-glucuronide in the rat formalin test. Norhydromorphone was isolated and identified as a metabolite of hydromorphone in a cancer patient's urine.