No pharmaceutical opinion available for this interaction.
Atazanavir / ritonavir can inhibit the metabolism (CYP 3A4 and 2D6) and increase the plasma concentration of Oxycodone.
3A4, P-gp/3A4 > 2D6, P-gp
Ritonavir: 1A2, 2C9, 2C19, UGT, 2B6, 3A4 (auto-induction)
3A4, UGT1A1, P-gp E et 2C8/3A4 > 2D6 > 2A6, 2E1, P-gp, MRP2
3A4 (major) (noroxicodone analgesic effect ~ 1% of the mother molecule), 2D6 (minor) (oxymorphone not much or not at all analgesic effect). Oxymorphone then is metabolized into norozymorphone by CYP3A4. P-gp by the blood-brain limb.
Possible increased risk of opioids toxicity.
Choose an alternative.
Otherwise, start with the lowest dose possible, or if patient already on oxycodone reduce dose up to 50% (individualize). Then adjust the dose depending on effectiveness of treatment and tolerance.
Monitor closely clinical efficacy and appearance of adverse effects.
In patients already being treated with this combination and tolerating it, if deemed appropriate, keep actual treatment and exercise close monitoring of adverse effects.
Morphine and hydromorphone. As a precaution, start with 60 to 75% of the converted dose of oxycodone.
Signs and symptoms of opioid withdrawal : craving for opioids, irritability, myalgias, muscle spasms, flushing, abdominal pain, nausea, vomiting, diarrhea, restlessness, diaphoresis, lacrimation, rhinorrhea, mydriasis, yawning, piloerection (goose flesh), tachycardia, tremulousness.
Signs and symptoms of opioid toxicity miosis, euphoria, dysphoria, drowsiness, confusion, excessive sedation, decreased alertness, hallucinations, dizziness, bradycardia, myoclonus, hypotension, prolonged or recurrent respiratory depression.
Ref #2588 : Co-administration with ritonavir 300 mg BID increased oxycodone AUC by 3.0-fold and Cmax by 1.7-fold. Co-administration with lopinavir/ritonavir 400/100 mg BID also increased oxycodone AUC by 2.6-fold and Cmax by 1.4-fold. With ritonavir and lopinavir/ritonavir, patients self-reported more oxycodone adverse effects.
See ritonavir + oxycodone and lopinavir/ritonavir + oxycodone.
Ref #2846 : A published study showed that the coadministration with voriconazole, a CYP3A4 inhibitor, increased oxycodone AUC and Cmax by 3.6-fold and 1.7-fold, respectively.