Nomographic estimation of time to reach steady-state serum concentration during phenytoin therapy.

The time to reach steady-state on phenytoin therapy depends on the dose and the pharmacokinetic parameter of the individual patient. A nomogram is presented to help the physician to decide whether a measured serum concentration of phenytoin can be regarded as being within 20% of the steady-state level. The nomogram is based on the pharmacokinetic parameters of phenytoin reported for adult patients.