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

FLS Science

Drugs suspected to be involved in the DDI-summary

Victim
Darunavir
Daily Dose
800 (mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
Unknown
End date
Unknown
Perpetrator
Psyllium
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.

Clinical 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)

University of Liverpool Recommendation

No clinically significant interaction expected
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