On January 16, 2008, Medtronic notified healthcare professionals about an increased rate of inflammatory masses in patients receiving intrathecal drugs through the company's Synchromed EL, Synchromed II and IsoMed implantable infusion pump systems. This letter, which also gave patient management and treatment recommendations, was an update to two earlier communications.
The company's analysis shows that the incidence of inflammatory masses is about five times higher (about 0.5 percent vs. about 0.1 percent) than it was in 2001 and is expected to continue to increase. The masses occurred at or near the distal tip of the intrathecal catheters, and have been reported with a variety of intrathecal infusions, including opioids, baclofen and pharmacy-compounded drugs. The highest incidence was reported with opioid use. High doses or high concentrations of opioids may increase the risk of inflammatory mass, but the exact etiology is not known.
The company's recommendations for managing patients include the following:
• With intrathecal opioids, administer the lowest effective dose and concentration.
• Closely monitor patients to identify the prodromal signs and symptoms of inflammatory mass.
• Consider a neurological consultation and imaging studies to confirm or rule out the presence of an inflammatory mass.
Finally, Medtronic strongly advises physicians to know which intrathecal drugs are approved for use in these devices, including preservative-free morphine sulfate sterile solution, Lioresal® intrathecal baclofen injection, and preservative-free ziconotide sterile solution. The effect of administering other drugs through these devices has not been assessed, and that includes drugs compounded by pharmacies.
FDA MedWatch Safety Alert. Medtronic Neuromodulation SynchroMed EL, SynchroMed II and IsoMed Implantable Infusion Pumps. March 21, 2008.