Metabolite question

Jenny P · Jan 2, 2002

Geez, Matt, I thought this was related to your "setting a bad example" thread and I was going to give you a hard time about dietary supplements! :D

mattcastens · Jan 2, 2002

No, Jenny, that would be a question about Metabolife, not metabolites.

TracyB,RN, RN · Jan 2, 2002

Well, I have seen a generic Metabolife supplement called, you guessed it, "Metabolite".

P_RN, ADN, RN · Jan 3, 2002

Not just renal patients I'd say. Propoxyphene AND Meperidine both do a job on older systems with their breakdown or lack thereof. Plus if you add any APAP to Darvon then you have another problem. Both should be avoided.

Though I will say I have seen many older ones who just loved their Darvocets. And many doctors who are all too happy to supply them.

Q. · Jan 3, 2002

HA! Matt I thought it was about skinny pills too!

LMAO!

aimeee, BSN, RN · Jan 3, 2002

I've been told that too, Matt, by pharmacists, physicians, and nurses who were expert in pain management. I've been searching for a web site that explains it well but its usually just stated as a general warning. This is the best I've found so far:

Darvon, Darvocet

"Metabolite norpropoxyphene has 1/2 life of 30-36 hours Norpropoxyphene is the metabolite and its

accumulation with repeated doses may be responsible for some of the observed toxicity.

Norpropoxyphene the active metabolite has local anesthetic effects and like lidocaine, may cause cardiac conduction delay (increased PR interval and QRS prolongation)."

"Bioavailability reduced 30-70% due to extensive 1st pass metabolism. 80% of drug is bound to plasma proteins and stored in fatty tissues. Great variability between people in the rate of clearance and plasma concentration. Crosses the placenta."

With a drug half life of 6-12 hours, and a metabolite half life of 30-36 hours, you can see the potential for problems, especially in people who have any sort of compromised ability to clear it.