Date of report: 21 Oct 2019
Reported case interaction between
Cobicistat and Quetiapine
Cobicistat and Quetiapine
Drugs suspected to be involved in the DDI
Drug A
Cobicistat
(Perpetrator)
Daily Dose
150
(mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
June 6, 2017
End date
Ongoing
Drug B
Quetiapine
(Victim)
Daily Dose
300
(mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
Jan. 1, 2011
End date
Ongoing
Complete list of drugs taken by the patient
Antiretroviral treatment
Darunavir/Cobicistat/Emtricitabine/Tenofovir-AF
Complete list of all comedications taken by the patient, included that involved in the DDI
Metahdone, Fluoxetine, Valproate, Midazolam and Quetiapine.
Clinical case description
Gender
Female
Age
49
eGFR (mL/min)
>60
Liver function impairment
No
Description
49 year-old woman with HIV infection on treatment with darunavir/cobicistat/FTC/TAF (before DRV/c+FTC/TDF and ATV/rtv + FTC/TDF; undetectable plasma viral load). Ex-IVDU on tretatment with methadone (50 mg qd). Depressive syndrome and personality disorder on treatment with Fluoxetine, Valproate, Midazolam and Quetiapine (300 mg qd) since 2011. Despite of being on ritonavir or cobicistat-containing regiments during her entire antiretroviral treatment history (since 2009), she has never presented quetiapine toxicity related symptoms.
Outcome
No unwanted outcome
Editorial Comment
Even if a relevant drug-drug interaction would be expected between darunavir/cobcistat/FTC/TAF and quetiapine as well as with darunavir/cobcistat/FTC/TAF and midazolam, no clinical relevant adverse events were observed. The European product label for quetiapine contraindicates the drug with CYP3A4 inhibitors (such as cobicistat), while the US product label recommends reducing quetiapine to 1/6 of the original dose in that setting. This is due strong CYP3A inhibition by cobicistat. Despite that no adverse effect was observed in this case, patients who need co-administration of quetiapine and CYP3A4 inhibitors muts be closely monitored.