No pharmaceutical opinion available for this interaction.
Atazanavir / ritonavir can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Zopiclone.
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) and 2C8
Increased risk of CNS toxicity.
Risk of prolonged sedation and respiratory depression.
Start with a dose of 3.75 mg QD and adjust according to efficacy and tolerance. Do not give more than 5 mg per day.
In patients already being treated with this combination and tolerating it, to avoid long-term problems, reduce the dose to a maximum of 5 mg daily and exercise a proper monitoring.
Monitor closely for adverse effects.
Or choose an alternative.
Lorazepam (Ativan), temazepam (Restoril), oxazepam (Serax).
Zopiclone adverse effects : anxiety, excessive somnolence, sedation, confusion, memory impairment.
Ref #3102 : Erythromycin, a CYP3A4 inhibitor, increases zopiclone AUC by 80%.
Ref # 3098: A safety alert from Health Canada (November 2014) recommends a reduced zopiclone initial dose of 3.75 mg (half a tablet of 7.5 mg) for older patients, those with impaired liver function or kidney or those who take a potent CYP3A4 inhibitor. The daily zopiclone dose should not exceed 5 mg.