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  • BDD Moderators: Keif’ Richards | negrogesic

From 90mg adderall to 50mg vyvanse!!! WTF!

belligerent drunk said:
The way I interpret the charts is that, as you say, the PK of free d-amp and lisdexamp are actually quite similar, except lisdexamp has a slightly slower onset and slightly longer duration. The amounts are in correct proportions (100 mg lisdexamp, metabolized into ~51 mg d-amp, corresponds to about same levels as 40-45 mg free d-amp) when equivalent stable levels are considered. So from this it would follow that the OP would need around 140 mg lisdexamp prescribed (to maintain the same levels as ~70 mg d-amp spread throughout the day), not the 50 mg they are. The dosage difference is still many-fold and that's what the doctor didn't consider, which was my initial point.

This is not the first time I see this type of thing, and I don't know if the doctors are unfamiliar with simple chemistry and maths, but this kind of gross dosage miscalculation seems pretty common when switching between d-amp and lisdexamp.

E: I realize that perhaps I illustrated my point poorly. I will say it this way: the OP were taking ~69 mg d-amp (90 mg 75%/25% ) spread into 3 doses each day, so that is say 23 mg d-amp per dose, 3 times a day. Then they got switched to 50 mg lisdexamp once a day, which (assuming roughly similar PK per mg d-amp as shown in the charts) equals about 25 mg d-amp equivalent - once a day. They were taking 3 times ~23 mg, now they're taking once 25 mg. There is the difference.
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Yes, and what I was getting at and mentioned was that his doctor was probably thinking this when he prescribed this amount, as most instant release medications are like this, such as Effexor. 75mg tid would be prescribed as 75mg Effexor XR. 100mg doesn't equate to 50mg, it would equal 30mg base dextroamphetamine once the lysine molecule is cleaved.
 
This thread should be about your WIFE. I thought you were fucking joking.. I'm more upset than you are I believe.



I would never be with a partner who would go behind my back and do something like that. Even if she was doing it out of so called "love for you", it was NOT her place and she should be reprimanded lol.
 
I made an appt with a new Dr. Today I took my 50mg vyvanse at 8am it kicked in around 9:30 and normally I crash around noon. So today at 11am I took another 50mg and didn't crash. I feel it starting to crash now but very slightly and it's 6pm. I'm fine with being tired at this time. I think I need either 2 50's or a 50 and a 70. Thats still only like 30-40mg d-amp total vs my old dose of 90mg adderall total so it's still less than 1/2 which is great as it should be better on my health. If s new Dr won't prescribe me two doses I'll just have to find it on my own bc this one dose is crap.
 
belligerent drunk said:
Not sure where you guys get your numbers from, but 50 mg of lisdexamphetamine metabolizes into approximately 25 mg of d-amphetamine, not 15 or 16 mg. Still, that is significantly lower than the previously used 67.5 mg, which explains why you're left dissatisfied. Overall, Crack'r gives pretty solid advice on how to approach the situation diplomatically.
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Are you sure because from what I researched The “conversion rate” is measured at 0.2948, meaning 30mg Vyvanse is equal to 8.85 mg dextroamphetamine, or 11.8 mg Adderall. Therefor 50mg vyvanse would be 14.74 d-amp.
 
theGirlWithBlueHair said:
Yes, about 15mg of d amphetamine. I misedited my text. I originally meant to say 100mg = 30mg of d amphetamine.
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How? Lisdexamphetamine molecular weight is 263, d-amp molecular weight is 135, which is roughly half of the former. You can also see from the chart you sent me how 100 mg of lisdexamp results in slightly higher plasma levels of d-amp than 40 mg of free d-amp. Considering the "time-release" of lisdexamp, it would be fair to say that maybe 100 mg = 40 mg d-amphetamine, but 30 mg is too low.
 
^ the question is, where do the 2 sources get their info from? Because the empirical data from the study you posted before clearly suggests that the conversion rate is significantly higher than 0.3 (more like 0.4-0.45). Do you not agree with that regarding the study and its charts, that you posted?
 
According to shire, 42% of d amphetamine is detectable in the urine following administration of lisdexamfetamine. This would mean 50mg would be equal to 21mg. But that was only 96% of the total dose. So it would be a little higher. I stand corrected. The study I posted is the correct one; previous beliefs are just hard to give up I guess.
 
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I don't really understand what you're referring to, can you elaborate? But what I was saying is that according to the charts you provided, to achieve similar plasma levels of d-amp as 40 mg of free d-amp, when using lisdexamphetamine you have to use approximately 100 mg of lisdexamphetamine, so the ratio is around 2.5 lisdex:d-amp, not 3.3 as suggested by those other sources. There is still a significant difference between the two, so it has to be considered. And I definitely agree that old beliefs are hard to give up for most people, which is a real shame.

Thanks for posting the charts by the way, I had a somewhat incorrect understanding of PK of lisdexamphetamine to be honest, but now I have a better idea.
 
Rofl. So many replies. Wait a week...if it does not work then tell your doc, if a week is too much try 4 days. And his wife might be a bummer, but it is better to not abuse meds. Adderall long term has awful effects on humans in multiple ways...it is legal speed
 
You have to remember that amphetamine itself undergoes metabolism too, so the 42% recovered from urine is what was left after metabolism and excretion, so it's not indicative of how much active d-amphetamine lisdexamphetamine corresponds to in plasma. That is to say that if you ingest 50 mg of free d-amp, you're not going to recover 50 mg of d-amp from urine.

I think the most accurate way to compare the two drugs is by plasma levels following administration (because that's what counts for activity and effects), and according to your charts, 50 mg lisdex would equal around 20 mg d-amp, not 25 mg (like I said) or 15 mg (like the other sources suggest).
 
^ no, it's very good that we went through all the aspects of this here, because it furthered my understanding of lisdexamphetamine pharmacokinetics, most likely provided you with some useful info, and anyone reading this later will also find a lot of useful data. Yeah, 70:30 sounds about right, and is in agreement with that other study.

I have been in and out of consciousness on 1,4-butanediol too all this time, so we're in the same boat in that sense, LOL.
 
^ Yeah but they'll get conflicting reports, until they get to pg.2 lol


-hs
 
belligerent drunk said:
^ no, it's very good that we went through all the aspects of this here, because it furthered my understanding of lisdexamphetamine pharmacokinetics, most likely provided you with some useful info, and anyone reading this later will also find a lot of useful data. Yeah, 70:30 sounds about right, and is in agreement with that other study.

I have been in and out of consciousness on 1,4-butanediol too all this time, so we're in the same boat in that sense, LOL.
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Haha, similar drugs. what a coincidence that is. I agree with the 70: 30. Which means the 150 I take is a little above 60mg, not 45. Which sounds more akin to the effects produced. And when I first took 200mg and later found out it only converted to 60mg, I was a little incredulous, to be honest.
 
bearing in mind that adderall is mixed salts and not just d-amp ...
30mg vyvanse is equal to ~12mg adderall IR, so 50mg would be about equal to 20mg adderall IR, and it is a very long acting medication so no need for redosing. you may be technically getting a slightly lower dose but for some vyvanse's effects are significantly stronger than adderall (or vice versa, vyvanse because of the way it is metabolized can vary widely in the way it is experienced person to person).
you seem to be overreacting.
 
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