Comparative Med
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Comparative Study
A single dose of liposome-encapsulated oxymorphone or morphine provides long-term analgesia in an animal model of neuropathic pain.
An extended-release formulation of oxymorphone was produced by encapsulation into liposomes, using a novel technique. Liposome-encapsulated morphine was produced, using a standard technique These preparations were tested in an animal model of neuropathic pain. Male Sprague-Dawley rats (approx. 300 g) were allotted to control (non-loaded liposomes) and treatment (liposome-encapsulated oxymorphone or morphine) groups. ⋯ Non-ligated rats treated with liposome-encapsulated oxymorphone had a small, but significant increase in thermal withdrawal latency from day four through day seven. One subcutaneous injection of liposome-encapsulated oxymorphone or morphine was effective in preventing hyperalgesia in this pain model for up to seven days. These results suggest that liposome-encapsulation of oxymorphone offers a novel, convenient, and effective means to provide long-term analgesia.