Ritonavir or lopinavir/ritonavir significantly increase plasma concentrations of oxycodone in nutritious human volunteers because of inhibition of CYP3A4 and CYP2D6.[fifty eight] Rifampicin significantly decreases plasma concentrations of oxycodone because of solid induction of CYP3A4.Canadian oxycodone HCL/acetaminophen five/325 mg tablet In Febru