Common antidepressants interact with the opioid pain medication tramadol and make it less effective at relieving pain, according to a study from University Hospitals (UH) published in Pharmacotherapy. The results have important implications for the opioid epidemic, as they indicate that some patients suspected of drug-seeking could be under-medicated and simply trying to alleviate their pain. The findings may also shed light on why some people exceed their prescribed tramadol dose, increasing their risk of addiction.
Researchers reviewed the records of 152 patients who had received tramadol for at least 24 hours. All study participants were either inpatients or under observation status. Patients who also were taking the antidepressants Prozac (fluoxetine), Paxil (paroxetine) or Wellbutrin (bupropion) required triple the amount of pain medication daily to control “breakthrough” pain throughout the day compared with patients not taking those antidepressants.
Upon a secondary analysis, the researchers discovered that the amount of pain medication required by the antidepressant group over their entire hospital stay was four times as much as patients not taking antidepressants.
In previous studies with healthy volunteers, effects on blood levels were observed when tramadol was combined with these particular antidepressants. However, the current study is the first to document the effects of this interaction in a real-world setting with patients.
Tramadol relies on the CYP2D6 enzyme being activated for pain control, but the enzyme can be inhibited by medications that are strong CYP2D6 inhibitors, such as fluoxetine, paroxetine, and bupropion, say the researchers.
Many patients with chronic pain also take antidepressants, primarily selective serotonin reuptake inhibitors (SSRIs), which encompass many of these CYP2D6 inhibitors. The researchers estimate that millions of Americans could be suffering from the effects of this drug-to-drug interaction.
Fortunately, there is a relatively easy solution for patients. Many of the other antidepressants in the same class of medication don’t inhibit CYP2D6, such as Zoloft (sertraline), Celexa (citalopram), and Lexapro (escitalopram). Also, other options for pain control include non-opioid medications such as NSAIDs. If there is a need to use opioids, a scheduled morphine or oxycodone treatment would avoid the potential interaction.
Source: University Hospitals, June 25, 2019