"X"mg of Vyvanse is NOT "X"mg of lisdexamphetamine!!!!!! Common knowledge?

[D.pharm]

"X"mg of Vyvanse is NOT "X"mg of lisdexamphetamine!!!!!! Common knowledge?

I often read people saying in posts that after your body cleaves off the enzyme necessary to metabolize lisdexamphetamine into d/amphetamine it is 1:1 ratio.

i.e I took 140mg of Vyvanse so that is like taking 140mg of d/amph after metabolization.

This information is incorrect

First of all 70 (or whatever) mg of Vyvanse does NOT mean you are taking 70 (or whatever) of lisdexamphetamine
(spell it with an "f" instead of "ph" if that makes you happy)

People do not often read the physician prescribing guidelines the manufacturer sends to the prescribing physician.
It wouldn't surprise me if your doctor didn't read it either.

NEWSFLASH

Your X mg capsule of Vyvanse is not actually lisdexmphetamine
Your X mg capsule of Vyvanse is actually lisdexamphetamine DIMESYLATE

This translates into only slightly more than 50% of actually bio-available lisdexamphetamine


According to Shire:

VYVANSE capsules contain 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, 60 mg, and 70 mg
of lisdexamfetamine dimesylate (equivalent to 5.8 mg, 11.6 mg, 17.3 mg, 23.1 mg,
28.9 mg, 34.7 mg, and 40.5 mg of lisdexamfetamine).

This may well have been mentioned in another post ..I did UTFSE but I see this mistake in threads all the time.

Especially if you are messing around recreationally you should know exactly how much of what you are actually ingesting.

So if you haven't done the math already expect a slightly more than 50% equivalency ratio from Vyvanse to d/amphetamine after metabolization.

PM if this is already common knowledge and I'll delete the post

 

[d1nach]

Interesting im tired but ya i got similar results guessing 96 g/mol methane sulfonic acid * 2 192 263 g/mol lisdexamph 192+263 455 g/ mol lisdexamph dimethansulfonic acid 263/455= 0.57

10mg *0.57=5.7 mg

I could be wrong i did this in my head. But it does seem your right very interesting

 

[Tubbs]

I'm gonna move this to neuroscience and pharmacology.

 

[sekio]

I often read people saying in posts that after your body cleaves off the enzyme necessary to metabolize lisdexamphetamine into d/amphetamine it is 1:1 ratio.

It's a 1:1 molar ratio, not a 1:1 weight ratio. Obviously it doesn't make sense having something metabolically split off and yet somehow gain weight.
MW amphetamine base is 135.2 g/mol, MW lisdexamphetamine base is 263.37 g/mol. MW amphetamine sulfate is 233.28 g/mol.

In 10mg of lisdexamphetamine dimesylate there is therefore 5.8mg of lisdexamphetamine base which translates to 2.2*10^-5 mols, or 2.97 mg of amphetamine base, or 5.13 mg amphetamine sulfate.

 

[Coolwhip]

I thought this was common knowledge, but I could be wrong...maybe its not among teenagers or college kids. I mean I am sure all the details and math behind it are foreign to most people, but at the end of the day, nobody thinks 10mg of vyvanse is 10mg of amphetamine base, just like no one thinks 10mg of adderall is 10mg of amphetamine base.

 

[som3dankbudz]

As you most likely heard before lisadexsfetamine is 1/3 dextroamphetamine by weight. Adderall is 3/4 dexamp 1/4 Levo amp a 40 mg vyvanse is equapotent to about 15 my adderall; technically sense it's in the dimeslyate form and the metabolite dexamp is in a form unknown to me, but I've always heard that vyvanse is more potent than the latter. Just felt obligated to enlighten you.

*vyvanse more potent mg per mg than the above said equivalency.