Significant interaction between activated charcoal and antiretroviral therapy leading to subtherapeutic drug concentrations, virological breakthrough and development of resistance.
A 42-year-old, treatment-experienced woman, virologically suppressed on tenofovir/emtricitabine and boosted atazanavir, experienced virological breakthrough, drop in CD4(+) T-cell count and undetectable drug concentrations. Adherence to treatment was confirmed, but repeat testing yielded similar results. After 2 months, the patient stated that she had been taking activated charcoal to manage gastrointestinal symptoms associated with her combination antiretroviral therapy, but she had recently discontinued the charcoal. Atazanavir concentrations were therapeutic but the patient's viral load rebounded and genotype testing revealed new reverse transcriptase mutations. The patient was changed to zidovudine, lamivudine, and boosted darunavir and achieved viral suppression. At 1 year follow-up, her viral load remained <40 copies/ml. According to the drug interaction probability scale, our patient experienced a probable drug interaction between activated charcoal and atazanavir/ritonavir leading to virological breakthrough and development of resistance.
Immunodeficiency Clinic, Toronto General Hospital, Toronto, ON, Canada. alice.tseng@uhn.ca.
Alice L
AL
Tseng
Charles
C
la Porte
Irving E
IE
Salit
D000328:Adult; D019380:Anti-HIV Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D002606:Charcoal / Q000009:adverse effects*; D024882:Drug Resistance, Viral; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology*; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D009154:Mutation; D016896:Treatment Outcome; D019562:Viral Load
D019380:Anti-HIV Agents; D002606:Charcoal