This model was designed based on my understanding and behavior of Dexedrine Spansule, and to explore dosing strategies with the medication.
Dexedrine Spansule is a Sustained Release (Matrix Type) medication, containing 50:50 of unprotected d-amphetamine and protected d-amphetamine. The release window of these two capsules creates two spikes of delivery, one at hour 1, and one at hour 4. This model has been roughly calibrated to observed studies of d-amp, but I am absolutely guessing at some components.
Pay attention to the effect tab in the simulation, I THINK that window of time you get a focusing effect is when your blood concentration of d-amp is increasing, as it decreases you withdraw. I haven't being able to verify this assumption. But I know it's not as simple as "more d-amp more focus" because rather than reach peak effectiveness at peak concentration, it stops working all together.
"The importance of the rate of increase of synaptic dopamine concentrations to the induction of stimulation and euphoria is exemplified by the observation that bupropion and GBR 12909 were not experienced as stimulant or euphoriant by normal volunteers"
I also know it's not as simple as this, but it seems a reasonable guide
Here are the relevant sources I used to build this simulation
