Date of report: 29 Sep 2022
Reported case interaction between
 Cobicistat and Dexamethasone

FLS Science

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
Jan. 1, 2017
End date
Unknown
Drug B
Dexamethasone (Victim)
Daily Dose
16 (mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
May 20, 2022
End date
Unknown

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

Dexamethasone, amlodipin, olmesartan

Clinical case description

Gender
Male
Age
56
eGFR (mL/min)
>60
Liver function impairment
No
Description

56-year-old male with HIV infection on ART with DRV/cobi/FTC/TAF since 2017. Virologically suppressed (<20 copies/mL). In May 2022 he is prescribed with dexamethasone 8 mg bid due to lumbalgia. Two days after starting to take dexamethasone he starts having uneasiness, anxiety and insomnia. After consultation, ART was switched to DTG/3TC with resolution of symptoms.

Outcome

Toxicity

Drug Interaction Probability Scale (DIPS)

Score
5 - Probable

Personal information from the specialist

Name
José
Surname
Moltó
Institution
Fundació Lluita contra la Sida
Country
ES

Editorial Comment

Cobicistat, as a potent inhibitor of CYP3A4 is expected to increase dexamethasone concentrations.  Dexamethasone itself is a moderate inducer and with prolonged exposure can also reduce expssure to of CYP substrates. In this case, the most most suitable intregrase inhibitor to switch to would be dolutegravir as descrined, since it is primarily metabolised by UGT1A1 and to a much lesser exptent by CYP3A4.