Stimulants Is there a direct relationship between metabolism and drug duration?

[psychomantis]

So I started vyvanse for add and inability to complete work. I am not taking this drug to get high, only taking it to treat this issue that effects my life.
A common thing that happens with most substances i take and have used in the past, is that they come on strong and quick, but quickly leave my system and the effects are not as long as advertised.
I am a skinny person and always have been. I have normal blood pressure.
I am wondering if my metabolism has anything to do with why drugs wear off so quickly yet come on so strong, I want to try to avoid this so I can use the drug to treat my issues effectively.
I am not sure that this has to do with the dose, because i feel the drug when I take, so this is specifically about duration. Vyvanse is advertise to last the majority of the day.
I just dont want to peak so hard with it initially and come off of it so quickly, what can I do to have a normalized experience?
Something else to add, is that through out the day i will get these little micro come downs and feel depressed, this wears off but it does happen. This is the main thing that is making me question if i have some sort of inconsistent thing going on in my body to begin with, would like to know what it could be. It doesnt feel mental, more like all my energy goes away for a little bit.

Worth noting, I am prescribed percocet for backpain/nerve damage. The effect seems to apply mostly to stimulants, like coffee and vyvanse. I have a habit of getting into routines where i drink coffee around the clock, because i have started vyvanse and because I also have some anxiety issues in addition to the add I am cutting back on the coffee.

Vyvanse is helping and I want to get an effective experience from it, all input is greatly appreciated.

 

[e92]

lol your thyroid doesn't digest a drugs chemicals, your body metabolizes the drug and it is then absorbed into the blood stream. it has nothing to do with your "metabolism"

 

[Kittycat5]

lol your thyroid doesn't digest a drugs chemicals, your body metabolizes the drug and it is then absorbed into the blood stream. it has nothing to do with your "metabolism"

No, a drug is absorbed first if taken orally. It can then either be partially metabolized before it reaches the circulation by the first pass effect, distribute into the blood, or distribute into other tissues. The amount in the blood is what allows a drug to exert its action at its intended site, then it is further metabolized and excreted.

Psychomantis, define metabolism. Do you mean that you can eat whatever and not gain weight or are talking about how the body actually metabolizes drugs?

Have you considered your diet affecting Vyvanse duration? An acidic diet will shorten it, a more alkaline one will increase it.