Analgesic applications for a subcutaneous implant that continuously releases hydromorphone

Opioids remain a critical component of the treatment of moderate to severe pain. Although the preferred method of opioid administration is oral, additional administration routes include intravenous, subcutaneous, transdermal, transbuccal, rectal, or intraspinal. Subcutaneous opioids have been used extensively in both in-patient and out-patient settings. The most commonly used subcutaneous opioids in the United States are morphine and hydromorphone which are administered by intermittent subcutaneous injections or via a subcutaneous needle attached to an external pump which provides either a continuous infusion or a continuous infusion combined with patient controlled analgesia boluses as needed for breakthrough pain. A novel subcutaneous implant is currently under development that will provide a continuous subcutaneous infusion of hydromorphone for 1-3 months. This could significantly affect the management of patients with cancer or other painful conditions as well as animals with chronic or post-operative pain. This manuscript reviews the potential therapeutic opportunities as well as the challenges in introducing and using this novel polymeric implant to treat pain in patients and companion animals.