The concept of microdosing was initiated by William Witt, MD, a former chairman of anesthesiology at University of Kentucky, who has now become a pain doc in private practice. The concept is based on the fact that the use of very small doses , a few micrograms per day, of an opioid will activate the mu receptors without flooding them or causing hyperalgesia. There is some weak rat science to support this, but less clinical science. The protocol for patient selection requires effectively complete withdrawal from all opioids for an extended period of time. If they can do this, then the microdose trial is performed, then implantation. Tolerance does develop at the same rate as normal dosing but the dosing is so small, that 3 times the rate after a year is still very small. Critics say the selection criteria effectively choose those who do not need opioids in the first place, therefore the use of a microdose intrathecal pump is like using a sledge hammer when minimal dose oral codeine would work just as well. There are no comparative studies between groups, and details on the process are hard to come by. I received a slide presentation by Medtronic that touted this approach but was very generic without a lot of details. Josh Wellington, the pain director at IU, also uses this approach in some patients and lectures on the process.
