Comparing the Effectiveness of IV and Oral Acetaminophen in Managing Postop Pain
Acetaminophen is commonly included in multimodal pain management protocols for total joint arthroplasty patients. It is effective in managing postoperative pain and has few contraindications.
With intravenous (IV) acetaminophen now readily available, is it time to replace the oral form of the drug in these protocols? Would that improve pain management while patients are in the hospital or ambulatory surgery center?
The answer is unclear: Few studies have evaluated the clinical benefits of IV acetaminophen versus oral acetaminophen.
In a study presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, researchers from the Hospital for Special Surgery in New York sought to answer the question, at least for total hip arthroplasty (THA). They hypothesized that THA patients who received IV acetaminophen would have less pain with activity and use fewer opioids, thus experiencing fewer opioid-related side effects, than patients who received oral acetaminophen.
As it turned out, IV and oral acetaminophen worked equally well.
“At a time when healthcare costs are increasingly under the microscope, the study supports the use of oral acetaminophen, which is less costly and less invasive to administer,” said Geoffrey Westrich, MD, the Director of Research for the Adult Reconstruction and Joint Replacement Service at Hospital for Special Surgery, who presented the study.
The study has also been published online in advance of print publication in the Journal of Arthroplasty. 
The double-blinded study included 154 patients who underwent THA at Hospital for Special Surgery and were randomly assigned to 1 of 2 groups:
- Oral acetaminophen with an IV placebo
- IV acetaminophen with an oral placebo
In addition to the study drug and placebo, all patients received standard multimodal pain management consisting of:
- Spinal-epidural anesthesia
- Epidural analgesia with bupivacaine and clonidine
- IV ketorolac
- Oral meloxicam
- Oral tramadol as needed for mild or moderate pain
- Oral oxycodone as needed for severe pain
The researchers set 3 primary outcomes for the study:
- Pain with physical therapy on POD1
- Opioid Related Symptom Distress Scale score on POD1
- Cumulative opioid use for the first 3 postoperative days
Although they said the results may be different for a different multimodal pain management protocol, the researchers found no significant differences in these outcomes for patients in both arms of this study.
“Patients in both groups had low pain scores with activity, minimal opioid-related side effects, and limited opioid usage,” Dr. Westrich said. “The big picture highlights multimodal analgesia overall as an effective method of pain control after joint replacement surgery.”
Westrich GH, Birch G, Muskat A, Padgett DE, Goytizolo E, Bostrom MPG, Mayman DJ, Lin Y, YaDeau J. IV vs. Oral Acetaminophen as a Component of Multimodal Analgesia After Total Hip Arthroplasty: A Randomized, Double Blinded, Controlled Trial (Paper 136). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
- Westrich GH, Birch G, Muskat A, Padgett DE, Goytizolo E, Bostrom MPG, Mayman DJ, Lin Y, YaDeau J.IV vs. oral acetaminophen as a component of multimodal analgesia after total hip arthroplasty: a randomized, blinded trial. J Arthroplasty. Article in press. doi: https://doi.org/10.1016/j.arth.2019.02.030.