Phenytoin Michaelis-Menten Dose Adjustment

Adjusts phenytoin dosing by saturable Michaelis-Menten kinetics — predicting steady-state level from a dose, dosing for a target level, or estimating patient Vmax — with salt-form correction; near saturation, small dose changes cause large level swings.

Calculation mode

Phenytoin formulation (salt factor)

Km, Michaelis constant (mg/L; blank = default 4.0)

Vmax, max metabolic rate (mg/day; required Mode A/B)

Administered daily dose, salt form (mg/day; required Mode A/C)

Target steady-state level (mg/L; required Mode B)

Measured steady-state level (mg/L; required Mode C)