In November 2012, Medtronic issued a warning letter regarding the use of off-label medications within its Synchromed II pain pump. This letter emphasized an increase of motor stalls within implantable infusion devices with unapproved drugs. This letter specifically stated, “The use of unapproved drugs can lead to intermittent or permanent pump motor stalls which may be reported as a loss of or change in therapy. Therapy changes could potentially result in serious injury and/or death.”
This study looked specifically at the rate of motor stall over time between pumps that were exposed to off-label drug use versus those that used FDA-approved medications. The Implantable Systems Performance Registry (ISPR), Medtronic’s prospective surveillance registry that systematically tracks device-related events and reliability, released its annual product performance report documenting the study. Data was collected between August 2003 and July 2011 derived from 4,891 infusion pumps registered and tracked. The study found that Synchromed II (Medtronic) pumps that utilized FDA-approved medications had a survival rate of 97.6% after 78 months versus a 93% survival rate for pumps that utilized off-label medications. This took all therapies into consideration.
The adverse event of motor stalls is pump failure. The clinical consequences of pump failure places heavy focus on therapy interruption (there is no data suggesting an increase in mortality). However, failures associated with off-label drug use are less common than catheter failures, which have the same consequences as motor stalls.
There was no shying away from the facts: compounded intrathecal drugs are a standard of care, and this is supported with numerous publications including the PACC 2012 guidelines. Motor stalls may cause an interruption of treatment, and off-labeled medication use may result in a decrease in pump life. Clinicians must make wise choices in the use of medications that are clinically required for the treatment of chronic pain. In addition, physicians must become acutely aware of potential issues that would lead to therapy failure, which also includes catheter failure. The ISPR 2011 Study showed 17% of catheter failures occurred within six years.
The North American Neuromodulation Society (NANS) stated, “Many experienced implanters agree that certain patients require off-label pump medications and medication admixtures to achieve adequate pain relief and to deprive patients of these medications will result in a loss of pain control and decrease in quality of life.”
NANS furthered its response by stating, “In medical practice, it is reasonable, acceptable and sometimes necessary for physicians to use off-label medications to effectively treat . . . patients with intractable chronic and cancer pain.”
In summary, motor stalls can cause an interruption of therapy; however, there is no data to suggest that pump failures are associated with overdosing of IT medication. Clinicians need to educate their patient on signs and symptoms of therapy withdrawal. The current PACC 2012 guidelines for drug selection, drug admixtures and monitoring remain relevant. Catheter failures have the same consequences as motor stalls. There is a need to study compounded drug characteristics and admixtures which are administered through the various pumps.
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