Date of report: 27 Feb 2020
Reported case interaction between
 Darunavir and Psyllium

FLS Science

Drugs suspected to be involved in the DDI

Drug A
Darunavir (Victim)
Daily Dose
800 (mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
Unknown
End date
Unknown
Drug B
Psyllium (Perpetrator)
Daily Dose
Unknown
Dose adjustment performed
No
Administration Route
Oral
Start date
Unknown
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
Gunabasic, lipidum

Clinical case description

Gender
Male
Age
44
eGFR (mL/min)
>60
Liver function impairment
No
Description
HIV patient experiencing virologic rebound (mean HIV RNA: 80 copies/mL) after starting using two CAMs a few weeks before. Gunabasic, which is a taraxacum‐containing dietary supplement claimed to be a draining agent; and Lipidyum, which is a dietary supplement of phytosterols (mainly psyllium) recommended as a nonpharmacological approach to constipation, hypercholesterolemia, and overweight. The patient was enrolled in a clinical trial aimed at assessing the efficacy of a once‐daily fixed‐dose formulation containing tenofovir alafenamide, emtricitabine, darunavir, and cobicistat; no TDM data were available. Remarkably, HIV viral load, assessed a few weeks after discontinuation of the weight‐loss agents, returned to < 37 copies/mL. This case has been published by Cattaneo D, et al. in Obesity (Silver Spring). 2018 Aug;26(8):1251-1252.

Outcome

Loss of efficacy

Drug Interaction Probability Scale (DIPS)

Score
4 - Possible

Editorial Comment

Weight-loss drugs should be used with caution in HIV-infected patients treated with antiretroviral drugs because of the risk of virologic failure. This episode could be related to psyllium, a soluble fiber from the husks of Plantago ovata that is able to increase stool weight and promote laxation; and is reported to decrease the absorption of calcium (Heaney RP, Weaver CM. Effect of psyllium on absorption of co‐ingested calcium. J Am Geriatr Soc 1995; 43: 261‐ 263)