One of the more interesting parts of spending time on the pain management services was getting more comfortable using methadone. Methadone is a synthetic opioid (mu-receptor agonist) which was developed in Germany in the 1930s since there were predictions of opium shortages. Methadone has a very long duration of action (making it well-suited for recovering addicts) and it also is a NMDA-receptor antagonist. This means it may help prevent some tolerance to opioids, and it can quell central nervous system responses to pain.
One of my patients was a young man with sickle cell disease, which leads to painful “vaso-occlusive” crises. These crises happen when the shape of the red blood cells becomes distorted, leading to obstruction of small vessels. Patients typically develop pain in their chest, shoulders, hips, and knees.
This particular patient had been in the hospital for nearly two weeks by the time I inherited him (as I came on the Chronic Pain Service on a Tuesday). He’d been intermittently refusing his long-acting oral morphine and insisted on using his substantial intravenous patient-controlled analgesia (PCA) pump. When I asked him why he refused his oral medications, he said they didn’t work for him. I explained that I believed the oral medicine did work for him, because when he took his medicine consistently, he required less intravenous medicine. The morphine was long-acting, so it didn’t produce a “rush” or “high”, but I explained that it provided a baseline level of pain control. He still seemed doubtful. I also told him that my goal was to get him off intravenous medications by the next day, and I was able to get him to agree to take his oral medicine.
Sure enough, by the next day, he’d refused a couple more doses of morphine. The cynic found within all pain specialists may interpret this as a sly move to exchange the pain control afforded by long-acting medicines for the euphoria of intravenous medications. Since one side-effect of opioids is sedation, if a patient is too sedated, he won’t push the pump’s button. This is the elegant safety feature inherent to PCAs. If a patient refuses long-acting medicine, that means he can get more intravenous medicine more frequently without becoming sedated.
At this point, I called the pain fellow to make sure he was on the same page as me, and then I lay down the law. No more intravenous medications. We’re starting methadone. The patient would have shorter-acting oral medicines available too, but only if he took his methadone. With the fellow, I did a multi-step conversion to determine the appropriate starting dose.
I was in for a surprise when I went to see the patient by the next day. He had received three doses of methadone by that point (one dose every eight hours). I’d double checked the nursing medication administration record to make sure he hadn’t refused them. And then I walked into his room. The patient was sitting in bed, awake, alert, and smiling. He stated that this was the first day in two weeks that he wasn’t in pain. Not only that, but since starting the methadone, he had not required any additional doses of shorter-acting oral medication.
Given the long half-life of the medication, it could potentially be building up in his system for days, so I titrated the dose down a tad. He was still comfortable the next day, so I recommended that he was okay for discharge with close follow-up with his hematologist.
Another satisfying success story for methadone!