Norvir and Tylenol interaction.

[Guest guest]

Norvir (Ritonavir) is an inhibitor of Cytochrome P450 isoenzyme

CYP3A4.

Tylenol (acetaminophen, paracetamol) has a complex 3 phase liver

metabolism CYP2E1, CYP3A4, CYP1A2 which then produces NAPQI, the

cause of Tylenol Toxity. Norvir boosts acetaminophen liver toxicity

to an

unknown level. 27 Extra Strength Tylenols (27g) will destroy your

liver.

When I took norvir and vicodin (hydrocodone/acetaminophen) for

peripheral neuropathy 2 tablets per week, my liver ALT increased to

111 over a 3 mo period. ALK PHOS was 117. I switched to Hycodan

(hydrocodone/ homotropine), and my ALT dropped back to 41 over a 3

month period. My Alk Phos also dropped back to 66.

Do not use Any tylenol containing products if you take Norvir. If you

have high liver ALT (alanine aminotransferase) and you take norvir

and any tylenol containing products, stop the tylenol and check your

ALT in 3 months.

To:

C

From:

WALFORD J. FESSEL MD

Received:

11/7/07 10:23 AM

Your info re the metabolism is both fascinating and clinically

relevant. It shows how extensive our knowledge gaps can be--even when

we do our best to maintain awareness!

Fessel MD.

----- Message -----

From: DAVIS,PAUL C

Sent: 11/7/2007 9:53 AM

Office of WALFORD J. FESSEL MD

Subject: RE: Paracetamol metabolism part 2

Hi Dr Fessel,

my ALT went up to 111 when I was taking vicodin and did not drop down

to 41 until we switched to hycodan for occasional peripheral

neuropathy pain.

I will no longer take paracetamol because of this. The phase 1

metabolites of paracetamol use CYP3A4 and were toxic enough to raise

my alt to 111.

Ref: O' P. Biochemistry notes: Role of Glutithione

(slide 4),2002

http://phm.utoronto.ca/~jeffh/phm%20acetaminophen.pdf

Medscape: http://www.medscape.com/viewarticle/557074