Beware of inflammatory masses from implantable infusion systems

June 16, 2008

Medtronic's recent recall of its implantable infusion systems underscores the need for health professionals to watch for inflammatory masses.

The recent recall of Medtronic's implantable intrathecal infusion systems due to the occurrence of inflammatory masses has underscored the need for physicians, pharmacists, and patients to be aware of the problem and monitor for it accordingly.

Although the incidence of inflammatory masses associated with implanted intrathecal infusion systems has increased, it is still relatively low at 0.49%. Marc Lapointe, Pharm.D., has worked with this population of patients for about 10 years. Out of an estimated 50 or more patients in his practice, Lapointe said he is aware of three patients who developed inflammatory masses.

Intrathecal therapy is used to treat patients with chronic pain or severe spasticity. By the time patients turn to intrathecal therapy, they have already tried and failed oral medications, surgery, or other methods of treatment. Implantable intrathecal pumps deliver continuous infusions of medications to the intrathecal space. Studies have indicated that patients treated this way have significantly less pain than with prior treatments.

Because intrathecal therapy delivers drugs directly to the intrathecal sac, intrathecal doses are 100 to 1,000 times lower than oral doses, LaPointe said. As a result, patients usually experience fewer and milder adverse effects.

But the intrathecal systems have some drawbacks. Implanting the systems requires surgery, which has inherent risks and is costly-the procedure can cost $20,000 or more per patient. There are also issues with mechanical mishaps and failures. The Medtronic intrathecal systems have been recalled several times in the past for various mechanical issues.

The latest recall is based on reports of inflammatory masses that may occur at or near the distal tip of intrathecal catheters. These masses have been reported with the intrathecal infusion of opioids, baclofen, pharmacy-compounded drugs, and other admixtures, according to both the Food & Drug Administration and Medtronic. The masses have been associated most often with relatively high doses of opioids.

Lapointe explained that compounded medications are used because they are less expensive. They can also be compounded in higher concentrations, allowing patients to have their pumps refilled less frequently. Medtronic is recommending that only medications FDA approved and indicated for use with the intrathecal systems be used for this type of therapy.

Lapointe said it's important for pharmacists to be aware of the symptoms of inflammatory masses in order to refer patients to their physicians for evaluation. "This technology is unique," he said, "but you have to be careful with it."

THE AUTHOR is a writer based in the Seattle area.

Most common symptoms associated with inflammatory masses

Use implantable intrathecal systems safely

When administering intrathecal opioids, the lowest effective dose and concentration should be administered.

In patients treated with intrathecal baclofen, physicians should closely monitor them in order to identify the prodromal clinical signs and symptoms of inflammatory mass, especially if using pharmacy-compounded drugs or baclofen admixtures that include opioids.

In patients with new neurological signs or symptoms, consider neurosurgical consultation and an imaging procedure to confirm or rule out the diagnosis of an inflammatory mass.

Infumorph (Baxter Healthcare Corp.), Prialt (Elan Pharmaceuticals), and Lioresal Intrathecal are the only drug products approved and indicated for use with the Medtronic implantable intrathecal systems. Drug products injected into the spine should never contain preservatives. Preservatives are not compatible with neurological drug infusion pumps and are neurotoxic.