CYP450 Pharmacogenomic Dosing Simulator

CYP450 Metabolizer Phenotype

Normal metabolizer — two functional CYP2D6 alleles, average enzyme activity. This is the reference clearance rate the drug label is dosed for.

Dosing Regimen

Dose per administration 150 mg

Dosing interval τ 12 h

Live Readouts

Plasma conc.

0.0 mg/L

Half-life t½

6.9 h

Steady-state C̄ss

14.4 mg/L

Time in window (72h)

How it works

The drug follows a one-compartment pharmacokinetic model with first-order elimination. Between doses, plasma concentration decays exponentially:

C(t) = C0 · e^(-ke·t)
ke = CL / Vd            (elimination rate constant)
t½ = ln(2) / ke         (half-life)

Each dose adds an instantaneous bolus C0 += Dose / Vd. Clearance CL is almost entirely carried out by the CYP450 enzyme, so a patient's genotype directly scales it:

CL = CL_normal × activity_score
PM (poor):         score ≈ 0.25  → CL cut to 25%, half-life ×4
IM (intermediate): score ≈ 0.50  → CL cut to 50%
EM (normal):       score = 1.00  → label dose is calibrated for this
UM (ultrarapid):   score ≈ 2.50  → CL ×2.5, drug cleared before it can act

At steady state (repeated dosing every τ hours) the average concentration is:

C̄ss = Dose / (CL · τ)

Poor metabolizers accumulate the drug dose after dose — the curve climbs above the toxic ceiling, the classic pharmacogenomic overdose risk (e.g. CYP2D6 poor metabolizers and codeine/tramadol, or CYP2C19 poor metabolizers and clopidogrel).
Ultrarapid metabolizers clear the drug so fast the curve barely reaches the therapeutic floor between doses — the standard dose simply fails.
The green band on the plot is the therapeutic window (minimum effective → minimum toxic concentration). This is the real basis for pre-emptive pharmacogenomic testing (CPIC/FDA drug-gene pairs) before prescribing narrow-therapeutic-index drugs.

t = 0.0 h

Plasma concentration Therapeutic window Dose administered

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.