System Overview
How Intrathecal Drug Delivery Works
Benefits of Intrathecal Drug Delivery
Historical Background

Medtronic's intrathecal drug delivery systems are composed of two implantable components: an infusion pump and an intraspinal catheter. The pump is placed abdominally in a subcutaneous pocket, while the catheter is inserted into the intrathecal space of the spine, tunneled under the skin and connected to the pump. Medication can be delivered at constant or variable flow rates.

Benefits of an Implantable, Programmable System

A totally implantable system may reduce the risk of infection compared to the long-term use of external systems.¹ Because there are no external parts, the system usually does not restrict daily activities. A programmable pump allows clinicians to adjust doses non-invasively, minimizing patient discomfort. In addition, the pump can be programmed to deliver different doses at various times of the day--meeting patients' changing needs.

The physiology of pain begins with sensory neurons called nociceptors. A pain message is transmitted along these neurons to the dorsal horn of the spinal cord. In the dorsal horn, sensory neurons release several neurotransmitters that act on the dendrites of ascending neurons. Eventually, these ascending neurons carry the signal to the brain where it is perceived as pain.

One of the key neurotransmitters in pain transmission is substance P. Opioids inhibit the release of substance P and other neurotransmitters by bonding to opioid receptors (e.g., morphine binds to Mu, Kappa and perhaps Delta receptors¹). This, in effect, blocks the message before it reaches the brain and is perceived as pain.

Intrathecal drug delivery places medication directly into the cerebrospinal fluid that surrounds the spinal cord. Morphine delivered directly to the intrathecal space is particularly effective because it does not have to circulate systemically to reach the CSF and the dorsal horn of the spinal cord. As a result, much smaller doses are needed (e.g., approximately 1/300 of an oral morphine dose), and the frequency of side effects is reduced. ^2,3

²Lamer, TJ. Treatment of cancer-related pain: when orally administered medications fail. Mayo Clin Proc1994; 69:473-80.

³Levy, R. Implanted Drug Delivery Systems for Control of Chronic Pain. Chapter 19 of Neurosurgical Management of Pain.New York, NY: Springer-Verlag; 1997.

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• Pain relief for patients whose pain has not been controlled with more conservative therapies. ^2,3
• Reduction in side effects such as nausea, vomiting, sedation and constipation. ^2,4
• Decreased need for oral analgesia. ^1,3
• Improved physical assessment and increased ability to perform activities of daily living. ^3,5

In addition, response can be evaluated by a screening test prior to system implantation.

Intrathecal drug delivery involves certain risks. For more information on risks and potential complications see Important Safety Information and Risks.

²Lamer TJ: Treatment of cancer-related pain: when orally administered medications fail. Mayo Clin Proc.1994 May;69(5):473-80. Review.

³Paice JA, et al: Intraspinal morphine for chronic pain: a retrospective, multicenter study. J Pain Symptom Manage.1996 Feb;11(2):71-80.

⁴Portenoy RK. Management of common opioid side effects during long-term therapy of cancer pain. Ann Acad Med.1994;23:160-170.

⁵Winkelmuller M, et al: Long-term effects of continuous intrathecal opioid treatment in chronic pain of nonmalignant etiology. J Neurosurg.1996 Sep;85(3):458-67.

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The first clinical implant of a Medtronic programmable pump for intrathecal morphine was performed in 1982. The SynchroMed^® pump for intraspinal morphine for nonmalignant and cancer pain was released in the U.S. in 1991.

System Overview
How Intrathecal Drug Delivery Works
Benefits of Intrathecal Drug Delivery
Historical Background