12.3 Interactions and overlapping toxicities between tuberculosis drugs and antiretrovirals

Certain combinations of TB drugs and ARVs are contraindicated or should be avoided or require dose adjustments of TB drugs or ARVs. For more information, see Appendix 19.

Note: drug interactions and overlapping toxicities between TB drugs and drugs other than ARVs are common. For example, rifampicin reduces plasma concentrations of fluconazole by 25%. It may be necessary to increase the dose of fluconazole. Conversely, fluconazole increases plasma concentrations of rifabutin. It is necessary to monitor for signs of rifabutin toxicity [1] Citation 1. European Medical Agency. Fluconazole: Summary of Product Characteristics. 2012.
https://www.ema.europa.eu/en/documents/referral/diflucan-article-30-referral-annex-iii_en.pdf . If patients are taking drugs other than ARVs, clinicians should be aware of potential interactions and overlapping toxicities.