HIV medication drug interactions

[michaelrack]

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I am studying for my consult psych recert boards. Various sources indicate that ritonavir and other HIV antivirals tend to lower methadone levels. According to the UCSF site, ritonavir may induce 3A4, thus lowering methadone levels: Interactions with Methadone.

However, other sources, including wikipedia, states the ritonavir inhibits 3A4 - thus increasing the levels of drugs such as statins.

the package insert (https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/209512lbl.pdf) indicates that ritonavir is a 3A4 inhibitor

Does anyone have an explanation??

 

[nitemagi]

Looks like it does both. Short term it's an inhibitor, chronically it's an inducer.
Impact of ritonavir dose and schedule on CYP3A inhibition and venetoclax clinical pharmacokinetics
The influence of combination use of CYP450 inducers on the pharmacokinetics of voriconazole: a systematic review. - PubMed - NCBI

and this:
Induction effects of ritonavir: implications for drug interactions. - PubMed - NCBI