Date of report: 09 Mar 2020
Reported case interaction between
Nevirapine and Dexamethasone

FLS Science

Drugs suspected to be involved in the DDI

Drug A
Nevirapine (Victim)
Daily Dose
400 (mg)
Dose adjustment performed
Administration Route
Start date
Dec. 10, 1998
End date
Nov. 15, 2018
Drug B
Dexamethasone (Perpetrator)
Daily Dose
8 (mg)
Dose adjustment performed
Administration Route
Start date
July 30, 2018
End date
Sept. 30, 2018

Complete list of drugs taken by the patient

Antiretroviral treatment
Complete list of all comedications taken by the patient, included that involved in the DDI
Dexamethasone, 5-Fluorouracil, Oxaliplatin, Bevacizumab, Atorvastatnin

Clinical case description

eGFR (mL/min)
Liver function impairment
55 year-old woman diagnosed with HIV in 1990 . She initiated ART in 1990 and plasma viral load had been under the limit of detection since 2001. Since 2011 she had been receiving ART with abacavir, lamivudine and nevirapine. In 2017 she was diagnosed with colorectal cancer. As first line therapy she received neoadjuvant radiotherapy and chemotherapy with capecitabine followed by surgical resection and chemotherapy with capecitabine. Some months later disease progression was observed, and a new chemotherapy scheme was initiated that included 5-Fluorouracil and Oxaliplatin in combination with Bevacizumab. Every treatment cycle chemotherapy was administered along with dexamethasone at a dose of 20 mg, as induction, followed by 4 mg twice daily for 3 days. A routine HIV control was performed after 11 cycles and plasma viral load was 515 copies/mL. The patien reported good adherence to ART, with no missed doses. A genotypic resistance test showed NRTI and NNRTI resistance-associated mutations (V75I, M184V and K101E). ART was switched to TAF/FTC/DRV/c, achieving undetectable plasma viral load.


Loss of efficacy

Drug Interaction Probability Scale (DIPS)

6 - Probable

Editorial Comment

Coadministration of Nevirapine (NVP) and Dexamethasone may decrease NVP and/or Dexamethasone plasma concentrations. To anticipate/characterize the drug-drug interaction, it is recommanded to monitor NVP plasma concentrations and steroid effects (not reported in the present case) At failure, the genotypic test performed on the corresponding plasma HIV-RNA (515 copies/mL) demonstrated a M184V mutation associated with 3TC/FTC resistance and with ABC partial resistance. It harbored also a K101E, which confered NVP resistance, potentially associated with low NVP plasma exposure. The Genotypic Sensitivity Score (GSS) is calculated to 0.5, explaining the virological failure related with the drug interaction. The switch from NVP + ABC/3TC to FTC/TAF/DRV/c (GSS = 2) and Dexamethasone discontinuation, led to a virological resuppression.