Therese Lindberg

therese.lindberg@cambio.se

@CambioCDS

To correct serum phenytoin level for renal failure and/or hypoalbuminemia.

Use in patients with albumin ≤3.2 g/dL (32 g/L). The “Sheiner-Tozer Equation” is the official name of this correction. This updated formula uses an albumin coefficient of 0.275, and 0.2 for patients with renal failure. FORMULA Corrected phenytoin = measured phenytoin level / ( (adjustment x albumin, g/dL) + 0.1) Adjustment = 0.275; in patients with creatinine clearance <20 mL/min, adjustment = 0.2. Note: no correction is needed for albumin >3.2 g/dL. This calculation is derived from the original Winter-Tozer formula, which used an albumin coefficient of 0.2, and 0.1 for renal failure.

1. Martin E, Tozer TN, Sheiner LB, Riegelman S. The clinical pharmacokinetics of phenytoin. J Pharmacokinet Biopharm. 1977 Dec;5(6):579-96. 2. Sheiner LB, Tozer TN. Clinical pharmacokinetics: the use of plasma concentrations of drugs. In: Melmon KL, Morelli HF, editors. Clinical Pharmacology: Basic Principles in Therapeutics. New York: Macmillan; 1978. p.71-109. 3. Winter MG, Tozer TN. Chapter 20. Phenytoin. In: Burton ME, Shaw LM, Schentag JJ, Evans WE. Applied pharmacokinetics: principles of therapeutic drug monitoring. 4th ed. Baltimore, MD: Lippincott Williams &amp; Wilkins, ©2006.

OBSERVATION.lab_test_phenytoin.v0, EVALUATION.phenytoin_correction_for_albumin__renal_failure.v0, OBSERVATION.laboratory_test_result-serum_albumin.v0