Richard is a 72-year-old veteran with a history of end-stage bilateral knee osteoarthritis. he underwent right total knee arthroplasty (tka) 3 days ago. he is currently taking oxycodone 5 mg with ibuprofen 800 mg three times daily for moderate post-op pain. he has a history of major depression that includes high levels of anxiety symptoms (anxious depression) which is treated with citalopram 20 mg daily and quetiapine 300 mg daily.