Date of report 20 Jun 2019
Reported case interaction between
Cobicistat and Tamsulosin
Cobicistat and Tamsulosin
Drugs suspected to be involved in the DDI-summary
Complete list of drugs taken by the patient
Tamsulosin, indapamide, enalapril, atorvastatin 20 mg qd, omeprazol, vitamin D
Clinical case description
72 year-old HIV patient on antiretroviral therapy with darunavir/cobicistat/FTC/TAF. Benign prostatic hypertrophy on treatment with tamsulosin 0.4 mg qd. Despite tamsulosin is metabolised mainly by CYP3A4, with potential increase in tansulosine exposure by cobicistat, no adverse events were observed in this patient using of low dose of tamsulosin.
Clinical Outcome
Editorial Comment
The recommendation in the tamsulosin SmPC is that tamsulosin should be used with caution in combination with strong and moderate inhibitors of CYP3A4, and cobicistat is a strong inhibitor. There are data with ketoconazole showing a 2.8-fold increase in exposure. Although this particular case with no unwanted outcomes does not mean you can automatically extrapolate to other patients on tamsulosin, it suggests that the lower dose of 0.4 mg of tamsulosin may be adequate with both ritonavir and cobicistat.
University of Liverpool Recommendation
Potential interaction - may require close monitoring, alteration of drug dosage or timing of administration