I am doing some research on medication interactions with Venclexta, and I noticed that it seems to interact with a lot of common medications, including acetaminophen, ibuprofen, common stomach upset medications like the proton pump inhibitors (omeprazole), steroids commonly used for AIHA (prednisone) plus a number of SSRI's used for depression.
The package insert states that the Venclexta dose should be decreased by at least 50% when taking another pg-p inhibitor, but my own personal experience showed that when adding another pg-p inhibitor to my stable Venclexta regimen (a statin, simvastatin), it was actually the second drug that we saw increased drug levels/effects of. My liver function is, and has stayed, normal. So however these meds interact in our liver, it seems it's not always as cut and dried as originally thought. This glycoprotein pg-p was only discovered in the early 1970's, so drugs using this mechanism of action are relatively new and whether they induce or inhibit other drugs is, IMO, not 100% ascertained. Because Venclexta was so "new" (compare to, say, aspirin), I chose to add the statin this way, instead of blindly following the "50% reduction rule." I knew, being a pharmacist, it can take years to determine in a drug-drug interaction which drugs' concentration may be affected. So I put it to the test, and for me personally, it seems reducing the statin dose by 50% got me the desired statin effect without cutting my Venclexta dose and risking CLL resistance. I will also add, we watched closely for increased Venclexta side effects like worsening neutropenia, thrombocytopenia, or anemia. In fact those cells are slowly creeping up towards normal. It was effects from too high a dose of the simvastatin that showed up in my bloodwork. Obviously, until a Venclexta blood level test is available, I can't say for sure I don't actually have a higher Venclexta level than I would without the simvastatin, but it's not enough to cause apparent adverse effects.
So I am putting this unlocked post out there to remind people to be cautious even when using OTC's while on Venclexta, and to discuss with their pharmacist/physician when considering adding or removing pg-p inhibitor drugs to their regimen, as well as "moderate CYP3A inhibitors", which the package insert also says necessitates a 50% Venclexta reduction. There are a lot of them out there, Rx as well as OTC.