correction
enoughorangejuice? said:
rulerofthecosmos - 10mg ritalin has 10mg of MPH in it, correct.
so a 50mg pill of this new lisdexamfetamine has 20mg of dex-amphetmaine in it, which is why i was wondering if there are more ACTIVE ingredients, because why is it a 50mg dose with 20mg of active ingredient? Why not just make the pills 20mg?
I'm thinking there are 30mg of some other active ingredient, maybe a non-psychoactive chemical, like l-amphetamine?
I don't know. Calling it 50mg and having 20mg of dexxy in it confuses me.
First, lisdexamfetamine is just Lysine (an essential amino acid that the body does not produce which is also sold as a supplement in most stores) coupled to dextroamphetamine. Plain and simple. What you were suggesting was that there was levo-amphetamine as well which would be amphetamine (d,l-amphetamine). Much like Ritalin (d,l-methylphenidate) is to Focalin (d-methylphenidate, the more active isomer), amphetamine (d,l-amphetamine) is to dextroamphetamine (d-amphetamine), also the more active isomer.
Moving on...
From the Vyvanse prescribing information:
/--SNIP--
In a human abuse liability study, when
equivalent oral doses of 100 mg lisdexamfetamine dimesylate and 40 mg immediate release d-amphetamine sulfate were administered to individuals with a history of drug abuse, lisdexamfetamine 100 mg produced subjective responses on a scale of “Drug Liking Effects” “Amphetamine Effects”, and “Stimulant Effects” that were significantly less than d-amphetamine immediate release 40 mg. However, oral
administration of 150 mg lisdexamfetamine produced increases in positive subjective responses on these scales that were statistically indistinguishable from the positive subjective responses produced by 40 mg of oral immediate-release d-amphetamine and 200 mg of diethylpropion (C-IV).
/--SNIP--
Extras.. .
(DAMP; D-AMP; d-AMP for short when used over and over in medical journals and drug trials). In case you were wondering, d-methamphetamine HCl; N-methamphetamine is written short-hand as d-MeAmp; d-MeAMP..
EDIT:
Apparently I didn't read your dosages correct. Yet your proof is in the PI snippit provided above

I thought that over too, the large dosages.
Citing Wikipedia's page on dextroamphetamine (
http://en.wikipedia.org/wiki/Dextroamphetamine ):
Vyvanse is available as capsules, in three strengths: 30 mg, 50 mg, and 70 mg.
A 30 mg-strength Vyvanse capsule is molecularly equivalent to 8.88 mg dextroamphetamine. However, this molecular equivalence would only hold true as a bioequivalence ratio if: the dimesylate salt instantly dissolved resulting in the complete dissociation of lisdexamfetamine ions, and then the covalent amide bond of every lisdexamfetamine molecule immediately underwent hydrolysis. In fact, being a prodrug, lisdexamfetamine has different properties than dextroamphetamine; for instance, lisdexamfetamine is metabolised in the gastrointestinal tract, while dextroamphetamine's metabolism is hepatic
(processed by the liver). [
# ^ FDA Approval of Vyvanse Pharmacological Reviews Pages 18 and 19 ]
However, on Wikipedia's
dextroamphetamine page, it states;
A 25 mg strength Vyvanse capsule is molecularly equivalent to 10 mg Dexedrine Spansules
(both the aforementioned pharmaceuticals are about 7.425 mg dextroamphetamine).
To sum this all up, you'll never get the same bioequivalence due to the fact that dextroamphetamine sulfate is immediate release and Vyvanse has to go through hydrolysis which brakes apart the lysine from the active ingredient dextroamphetamine. So, even though you can have equal equal molecular equivalence, it still will not be the same because Vyvanse has to go through these stages before the active drug is released.
Sorry for all the redundancy and stuff but I have that clarified the subject.
MODS: If this is a repeat post. please do as you see fit.
Thanks,
dehmmy