Effect of Duloxetine on Opioid Use After Total Knee Arthroplasty

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.