Lisdexamfetamine PK Model
d-amphetamine blood level simulation from LDX dosing. Educational use only.
Parameters
Wake time:
?
First dose is always taken at wake time.
Bedtime:
?
Target sleep time. Aim for under ~20 ng/mL d-amp for unimpaired sleep onset.
d-amp half-life:
h
?
Elimination half-life of d-amphetamine. Typical range 9–14h. Influenced by urinary pH, genetics, and hydration. Applies globally — including saved snapshots.
Baseline dose:
mg
?
Your usual daily LDX dose, used to model prior-day carryover (10-day steady state).
Doses & timing
Dose 1 — at wake (
):
mg
Dose 2
Amount:
mg
(= total − dose 1)
At:
Lock to total
?
Fixes dose 1 + dose 2 to a combined total. Adjusting dose 1 above automatically reduces dose 2 and vice versa. An “all at once” reference line is shown for comparison.
Total:
mg
Dose 3
Amount:
mg
At:
(clamped)
Urine pH modifier
?
Urinary pH strongly affects d-amphetamine renal clearance. Acidic urine (e.g. from Vitamin C / ascorbic acid) increases ionization and excretion, shortening the effective half-life. Basic urine (e.g. from potassium citrate) does the opposite, extending half-life. The effect builds immediately at the time taken and linearly wears off over the configured duration.
Vitamin C
(acidifies → shorter hl)
Potassium citrate
(alkalinizes → longer hl)
Taken at:
Effect duration:
h
Half-life shift:
h
?
How many hours the half-life shifts at peak effect. The half-life returns smoothly to baseline over the duration. Enable “d-amp half-life” in model internals to visualize this.
Save snapshot
Saves the current scenario as a comparison line on the chart.
Advanced: model internals
?
Overlay diagnostic traces on the chart. Each item uses its own right-hand axis so the d-amp scale is never affected.
Clear snapshots
Select traces to overlay on the chart:
LDX concentration
Conversion rate
Elimination rate
LDX % ceiling
d-amp half-life
Above ~80% ceiling the linear model overestimates d-amp output (enzymatic saturation at ~130mg LDX).
No dose today
Dose 1
+ Dose 2
+ Dose 3
All at once (
mg)
✕
LDX conc. (→)
Conv. rate (→)
Elim. rate (→)
LDX % ceiling (→)
d-amp hl (→)
Prior-day residual at wake
?
d-amp still in your system from yesterday’s dose (steady state). Bar shows this as a % of today’s expected dose-1 peak.
Peak
Bedtime