Effect of Duloxetine on Opioid Use After Total Knee Arthroplasty

Effect of Duloxetine on Opioid Use After Total Knee Arthroplasty: A Double-blinded Randomized Control Trial

Post-discharge pain after total knee arthroplasty remains problematic; many patients have excessive pain at the 2 week time point (and often thereafter). Reduction in opioid use has become a national goal, due to the 'epidemic' in opioid misuse.

In addition to enrolling non-opioid users, we will enroll up to 15 chronic opioid users.

Inclusion Criteria:

• Age 25 to 75 years
• Planned use of regional anesthesia
• Ability to follow study protocol
• English speaking (Primary outcome obtained via telephone call and secondary outcomes include questionnaires validated in English only)
• Patients planning on being discharged home or to a rehabilitation center that has agreed to participate

Exclusion Criteria:

• Current Use of duloxetine or other SNRIs, SSRIs, MAOIs, Tricyclic antidepressants, triptans (sumatriptan, rizatriptan, naratriptan, eletriptan, almotriptan, frovatriptan), lithium, buspirone, St. John's Wort

• Hepatic insufficiency

  o Hepatoxicity is reported as a side effect of duloxetine. "Median time to detection of transaminase elevation was about two months" (package insert 5.2

• Renal insufficiency (ESRD, HD, estimated creatinine clearance < 50 ml/min)

  • Severe CRI may impair duloxetine clearance
  • CLcr=[(140-age (years)] x weight (kg)x0.85 (for female patients)/[72xserum creatinine (mg/dL)]

• Patients younger than 25 years old and older than 75

• Patients intending to receive general anesthesia

• Allergy or intolerance to one of the study medications

• Patients with an ASA of IV

• Chronic gabapentin/pregabalin use (regular use for longer than 3 months)

• Patients with major prior ipsilateral open knee surgery.

• Chronic opioid use (taking opioids for longer than 3 months)

  • However, patients using chronic opioids may enroll in a parallel pilot study entitled 'effect of duloxetine on opioid use after total knee athroplasty among patients exposed to opioids- a pilot study'. The chronic opioid users will be allowed to continue their customary analgesics. The pilot study is otherwise identical to the main study.
  • This study will enroll up to 15 chronic opioid users. After that, all chronic opioid users are excluded.