Osimertinib (Tagrisso) with dexamethasone


Is anyone on Tagrisso (osimertinib) taking or took dexamethasone? I want to start my mum on osimertinib, but she is taking dexamethasone for brain lesion edema. I learned there might be interaction between these two : dexamethasone may reduce the blood levels of osimertinib, which may make the medication less effective in some cases. Does anyone have any experience or recommendations and did you have good response from Tagrisso while on dexamethasone?


Posts: 258

Hi Daxys,

Welcome to GRACE. It's best to discuss your concerns with your oncologist, but in the meantime if you look at the physician desk reference page on Tagrisso, which exhaustively lists all the drug interactions that are significant enough for doctors to take into account, it doesn't list dexamethasone or decadron.

See: http://www.pdr.net/drug-summary/Tagrisso-osimertinib-3828

Drugs can have weak interactions but not enough to change how medications are prescribed or patients monitored.

Since Tagrisso crosses the blood brain barrier, hopefully your Mum has a good response and it will shrink the mets in the brain so your Mum may not need to stay on Dexamethasone. Sometimes Tagrisso is prescribed at double dose (160 mg rather than 80 mg) for patients with brain mets.

Posts: 147

GRACE Community Outreach Team

Hi daxys,

I'll add my welcome to GRACE, as well as a bit more information in addition to what onthemark has already provided.

The interaction between osimertinib and dexamethasone is one which is predicted because dex is a weak CYP3A inducer. As onthemark points out, trial experience hasn't revealed enough of an interaction to warrant including dex interaction in the prescribing information for Tagrisso. In a study of such possible interactions, it was concluded:

Based on observed clinical data and PBPK simulations, the recommended dose of osimertinib when dosed with strong CYP3A inducers is 160 mg once daily. PBPK modeling suggested no dose adjustment with moderate and weak CYP3A inducers. - https://ascpt.onlinelibrary.wiley.com/doi/full/10.1002/psp4.12289

Although we wouldn't expect an interaction of any significance, at worst the dosage of either Tagrisso or dexamethasone would simply need to be adjusted.

Good luck to your mum with Tagrisso!

Forum moderator

Posts: 45

Thanks to both of you for your fast replies! I did some research yesterday and I guess I got basically the same information. Also I found a study which deals with various doses of osimertinib and confirms that there is no difference in efficacy :

So I guess even if there were some little interaction it should not change the effect of osimertinib. I would like that osimertinib does its best for my mum and still I would like to hear from people who took it along with dexamethasone.