Pfizer pill interaction

[ElMaga]

I read where the new covid pill (Pfizer) interacts with ibrutinib; I wonder how many days we must be off ibrutinib before we can take the pill, should we need it?

[cllady01 Former Volunteer]

It would be helpful to have the address (link) to what you have read.

[SofiaDeo]

The ritonavir component is a liver enzyme inhibitor, the same enzyme system used to metabolize ibrutinib. So any drug metabolized in the liver using these enzymes will likely result in increased blood levels of it, since it's not being metabolized & broken down normally. When you inhibit a liver enzyme, it doesn't metabolize a drug like it normally does. I would imagine many practitioners would have you stop the ibrutinib to be on the safe side, since stopping ibrutinib is not usually life threatening.

[AussieNeil Administrator in reply to SofiaDeo]

Exactly SofiaDeo, I would expect the medical response would be to stop or reduce the ibrutinib dose in accordance with how much Paxlovid, which is a combination of Pfizer's investigational antiviral PF-07321332 and a low dose of ritonavir, an antiretroviral medication, slows the clearance of ibrutinib.

ElMaga, here's the previous discussion on this topic:

healthunlocked.com/cllsuppo...

Specifically:- Re: Paxlovid Pill Approved for COVID 19 Treatment ... But check the Contraindications- Ibrutinib and Venetoclax

From: Rick Furman

Date: Wed, 22 Dec 2021 21:45:37 EST

Paxlovid is a CYP3A inhibitor and will impair clearance of many drugs. This would include all drugs with the "grapefruit" warning. Given the course is only five days, holding the agent is often all that is necessary, but dose reductions, etc. would also work.

Rick Furman

Neil

[ElMaga in reply to AussieNeil]

thanks, AussieNeil! always so helpful.

[Tapps]

Do I understand that Paxlovid, would interfere with Ibrutinib?

[AussieNeil Administrator in reply to Tapps]

Yes, as you've read above and per this reply healthunlocked.com/cllsuppo... either you need to hold ibrutinib or your ibrutinib dose needs to be reduced for 5 days.

Neil

[mrsjsmith in reply to AussieNeil]

Neil,

When I discussed this with my consultant because I had read about contras he suggested reducing the Ibrutinib to 140 because I am TP53 and he was concerned about stopping altogether.

Colette

[Tapps]

06/07/22 Plane trip from Florida MCO, to Seattle, SeaTac Washington. Tested positive; 06/12/22. Covid. Waiting for information from Doctor in the morning. Cough, Congestion upper, Headache, Backache,

Temperature 99.06

Taking Ibrutinib, CLL Unmutated

[ElMaga in reply to Tapps]

so sorry; wishing you a quick recovery