The main objective is to demonstrate that postoperative analgesia by IV oxycodone (compared to morphine IV) reduces opioid-related adverse events (nausea, vomiting, pruritus, respiratory depression, urinary retention, allergies, hallucination) by 50% in adult patients operated on for prosthetic hip surgery.

Inclusion Criteria:

• The patient must have given his/her informed and signed consent
• The patient must be insured or beneficiary of a health insurance plan
• The patient is available for a 4 month follow-up
• The patient weight between 50 and 100 kg
• Patient scheduled for unilateral hip arthroplasty
• Patient has creatinine clearance > 50 ml/min (Cockroft)
• Patient with ASA-PS score of 1, 2 or 3 (American Society Anesthesiology - Physical Status)

Exclusion Criteria:

• The patient is participating in another study
• The patient is in an exclusion period determined by a previous study
• The patient is under judicial protection, under tutorship or curatorship
• The patient refuses to sign the consent
• It is impossible to correctly inform the patient
• The patient is pregnant, parturient, or breastfeeding
• Patient with ASA score of 4
• Patient has a known deficit in cytochrome P450
• Uncontrolled epilepsy
• Chronic alcoholism
• Patient already taking opiate agonist on a long term basis (codeine, dextromoramide, dihydrocodeine, oxycodone po, morphine-like antitussif)
• Patient already taking agonist-antagonists on a long term basis (buprenorphine, nalbuphine, pentazocine)
• The patient is under treatment for liver inducing enzyme cytochrome P450: anti-infectives (e.g. rifampicin, rifabutin, nevirapine, griseofulvin), antiepileptic (phenobarbital, phenytoin)
• the patient has an allergy to opiates
• the patient has chronic renal insufficiency: creatinine clearance < 50 ml / min (Cockroft formula)
• the patient has severe hepatic insufficiency(transaminase and/or alkaline phosphatase x 3/nal))
• patient with porphyria, intracranial hypertension, a syndrome subocclusive or ileus