how long does strattera stay in your system?

[jimoc77]

I am switching from strattera to Ritalin because of the side effects of the Strattera. I was too tired and too emotional. My question is how long will the Strattera stay in my system. I want to accurately judge the dosage of my new meds and I don't want to have the effects to be falsely enhanced by the leftovers.

[BR549]

From the FDA.gov prescribing info
http://www.fda.gov/ohrms/dockets/doc...-Attach-1.pdf:

Metabolism and elimination — Atomoxetine is metabolized primarily through the CYP2D6
enzymatic pathway. People with reduced activity in this pathway (PMs) have higher plasma
concentrations of atomoxetine compared with people with normal activity (EMs). For PMs, AUC
of atomoxetine is approximately 10-fold and Css,max is about 5-fold greater than EMs. Laboratory
tests are available to identify CYP2D6 PMs. Coadministration of STRATTERA with potent
inhibitors of CYP2D6, such as fluoxetine, paroxetine, or quinidine, results in a substantial
increase in atomoxetine plasma exposure, and dosing adjustment may be necessary
(see Drug-Drug Interactions). Atomoxetine did not inhibit or induce the CYP2D6 pathway.
The major oxidative metabolite formed, regardless of CYP2D6 status, is
4-hydroxyatomoxetine, which is glucuronidated. 4-Hydroxyatomoxetine is equipotent to
atomoxetine as an inhibitor of the norepinephrine transporter but circulates in plasma at much
lower concentrations (1% of atomoxetine concentration in EMs and 0.1% of atomoxetine
concentration in PMs). 4-Hydroxyatomoxetine is primarily formed by CYP2D6, but in PMs,
4-hydroxyatomoxetine is formed at a slower rate by several other cytochrome P450 enzymes.
N-Desmethylatomoxetine is formed by CYP2C19 and other cytochrome P450 enzymes, but has
substantially less pharmacological activity compared with atomoxetine and circulates in plasma
at lower concentrations (5% of atomoxetine concentration in EMs and 45% of atomoxetine
concentration in PMs).
3
Mean apparent plasma clearance of atomoxetine after oral administration in adult EMs is
0.35 L/hr/kg and the mean half-life is 5.2 hours. Following oral administration of atomoxetine to
PMs, mean apparent plasma clearance is 0.03 L/hr/kg and mean half-life is 21.6 hours. For PMs,
AUC of atomoxetine is approximately 10-fold and Css,max is about 5-fold greater than EMs. The
elimination half-life of 4-hydroxyatomoxetine is similar to that of N-desmethylatomoxetine
(6 to 8 hours) in EM subjects, while the half-life of N-desmethylatomoxetine is much longer in
PM subjects (34 to 40 hours).
Atomoxetine is excreted primarily as 4-hydroxyatomoxetine-O-glucuronide, mainly in the
urine (greater than 80% of the dose) and to a lesser extent in the feces (less than 17% of the
dose). Only a small fraction of the STRATTERA dose is excreted as unchanged atomoxetine
(less than 3% of the dose), indicating extensive biotransformation.

Basically, Atomoxetine has a mean average half-life of 5.2 hours, with poor metabolizers (7% of the Caucasian population, 2% of the African American population in Lilly’s trials) taking up to 24 hours to process it. It further metabolizes again with a half life of 6-8 hours. So roughly a total half life of about 13 hours. Completely out of your system in about 3 days.

The elimination half-life of 4-hydroxyatomoxetine is similar to that of N-desmethylatomoxetine (6 to 8 hours) in EM subjects, while the half-life of N-desmethylatomoxetine is much longer in PM subjects (34 to 40 hours).

[Flory]

will your pdoc not calculate this for you and advise ?

[HouseFull4+1]

For what its worth, when my son came off Strattera (we gave him a full week before trying something new).... he was a little guy at the time and on a small dosage. I would defiantly double check with your Dr. or your Pharmacist (if you go to a mom&pop pharmacy.

Originally Posted by jimoc77

I am switching from strattera to Ritalin because of the side effects of the Strattera. I was too tired and too emotional. My question is how long will the Strattera stay in my system. I want to accurately judge the dosage of my new meds and I don't want to have the effects to be falsely enhanced by the leftovers.