I've been taking Vyvanse for a few months now. I usually take 2 50mg capsules in the morning and 1 10mg dex in the evenings as needed. This translates to around 35-40mg of d-amp from Vyvanse. I'm wondering what "continuous release" (Shire's description) means. Is there a large amount releasing during the first 3 hours followed by smaller amounts over the supposed 12-14 hour duration? If so, how much? Or are there 2 equal separate doses? (doesn't feel like it) I tried calling Shire, but they couldn't help me.

I figured I'd asked an impossible question or perhaps the answer is really obvious, but nobody has the heart to point this out. :confused: Has anyone seen a dose concentration graph? I know there's tons of smart people on here.

It's new - so I'm not sure exactly what the timetable is for release.

I do know though that since it is absorbed through the liver (IIRC due to the lysine) that it is more spread out than others which are absorbed through the stomach.

I believe (if I remember correctly) it's a smooth release similar to Concerta except not the OROS delivery. If that all makes since. It's a smooth delivery of the medication...

Hi there,
Yes, there is a study available with pharmacokinetic data for lisexamphetamine (LDX) administered once daily in the morning to healthy adults.

The citation is: Krishnan SM, et al. Multiple daily-dose pharmacokinetics of lisdexamfetamine dimesylate in healthy adult volunteers. Curr Med Res Opin. 2008 Jan;24(1):33-40.

PM me if you want more details- probably not a good idea for me to post copyrighted material. Suffice to say, the T(1/2) for LDX was 10.1 hours and a blood levels are pretty constant through 8 to 10 hours.

Of course this is not a pure half life, as LDX is metabolized to d-amph throughout the day, and d-amph is being metabolized and excreted at the same time.

Most suprising to me is that they found a steady state after 5 days! In other words, the drug is not completely eliminated in 24 hours. This makes Vyvanse distinct from any of the typical psychostimulants I know of that are indicated for treatment of ADHD.

From the drug plasma profiles I've seen (oddly enough Shire didn't include these with the prescription pamphlet for some reason) the med peaks very rapidly (3-5 hours) and just kinda stays there for a long duration of time.

I assume what is happening in the body is that the medication is digested in the GI tract hence the rapid peak but the amount of lysine the body can cleave off the medication is the limiting and thus long release part of Vyvanse.

J

Thanks everyone for the information. The adult study sounds very interesting. The peak knocks me for a loop...not because its too strong physically, but that it's so fleeting mentally (plus the artificial mood lift is confusing). I feel like I'm getting a huge dose in the beginning and then nothing after 6 hours, hence the addition of the IR Dex. Wish I was a smooth, consistent 12 hour responder.

Here is a link with some plasma profiles:

http://www.secinfo.com/d12Pk6.v9Ac.d.htm

J

2scattered: You may be an atypical metabolizer. I think there are tests for this kind of thing.

my vyvanse does not release how it's supposed to: onset is about 45min-1hr usually, then it reaches its peak at around 2hr (70%ish reduction in symptoms) maintains till hour 3.5 or 4, then peters out giving me another 5 hours of maybe 40% reduction in symptoms. I'm bringing this up with my doc when I go in next month, but I have a feeling he will be unsympathetic. Damn Uni docs, I need better local health insurance.