Predictive performance of the winter-tozer and derivative equations for estimating free phenytoin concentration

Canadian Journal of Hospital Pharmacy

Volumn 69, Issue 4, 2016, Pages 269-279

  Cheng, Wendy ^a   Kiang, Tony K L ^a   Bring, Penny ^b   Ensom, Mary H H ^c  

^a VANCOUVER GENERAL HOSPITAL   (Canada)

^b SURREY MEMORIAL HOSPITAL   (Canada)

^c UNIVERSITY OF BRITISH COLUMBIA   (Canada)

Author keywords

Phenytoin; Predictive performance; Winter Tozer equation

Indexed keywords

ALBUMIN; CREATININE; PHENYTOIN DERIVATIVE;

ADULT; AGE; ALBUMIN BLOOD LEVEL; ANDERSON EQUATION; ARTICLE; BLAND ALTMAN PLOT; CREATININE BLOOD LEVEL; CRITICALLY ILL PATIENT; DOSE; DRUG BLOOD LEVEL; ESTIMATED GLOMERULAR FILTRATION RATE; FEMALE; HUMAN; KANE EQUATION; KIDNEY FUNCTION; MAJOR CLINICAL STUDY; MALE; MATHEMATICAL PARAMETERS; MEASUREMENT ERROR; MEASUREMENT PRECISION; MEDICAL RECORD REVIEW; MIDDLE AGED; NEUROLOGICAL INTENSIVE CARE UNIT; PREDICTOR VARIABLE; SECONDARY ANALYSIS; SEX; STATISTICAL BIAS; WINTER TOZER EQUATION;

EID: 85016928239     PISSN: 00084123     EISSN: 19202903     Source Type: Journal    
DOI: 10.4212/cjhp.v69i4.1573     Document Type: Article

References (22)

1. Perucca E. Plasma protein binding of phenytoin in health and disease: relevance to therapeutic drug monitoring. Ther Drug Monitor. 1980;2(4): 331-44.
2. Gatta A, Verardo A, Bolognesi M. Hypoalbuminemia. Intern Emerg Med. 2012;7(3):S193-9.
3. Wilkinson GR, Shand DG. Commentary: a physiological approach to hepatic drug clearance. Clin Pharmacol Ther. 1975;18(4):377-90.
4. Therapeutic serum concentrations and sampling guidelines. In: Pediatric drug dosage guidelines.Vancouver (BC): BC Children's and Women's Hospital; 2015 [cited 2015 Aug 31]. pp. 225-228. Available from: www.pedmed.org/DrugApp/Supplementary/Therapeutic%20Drug%20Monitoring.pdf
5. Tozer TN, Winter ME. Phenytoin. In: Schentag JJ, editor. Applied pharmaco-kinetics: principles of therapeutic drug monitoring. 3rd ed. Vancouver (WA): Applied Therapeutics; 1992. pp. 25.1-25.44.
6. Beck DE, Farringer JA, Ravis WR, Robinson CA. Accuracy of three methods for predicting concentrations of free phenytoin. Clin Pharm. 1987;6(11): 888-94.
7. Bolt J, Gorman SK. Precision, bias, and clinical utility of the Sheiner-Tozer equation to guide phenytoin dosing in critically ill adults. J Clin Pharmacol. 2013;53(4):451-5.
8. Kane SP, Bress AP, Tesoro EP. Characterization of unbound phenytoin concentrations in neurointensive care unit patients using a revised Winter-Tozer equation. Ann Pharmacother. 2013;47(5):628-36.
9. Anderson GD, Pak C, Doane KW, Griffy KG, Temkin NR, Wilensky AJ, et al. Revised Winter-Tozer equation for normalized phenytoin concentrations in trauma and elderly patients with hypoalbuminemia. Ann Pharmacother. 1997;31(3):279-84.
10. Mauro LS, Mauro VF, Bachmann KA, Higgins JT. Accuracy of two equations in determining normalized phenytoin concentrations. DiCP. 1989;23(1):64-8.
11. Krasowski MD, Penrod LE. Clinical decision support of therapeutic drug monitoring of phenytoin: measured versus adjusted phenytoin plasma concentrations. BMC Med Inform Decis Mak. 2012;12(1):7.
12. Hong JM, Choi YC, Kim WJ. Differences between the measured and calculated free serum phenytoin concentrations in epileptic patients. Yonsei Med J. 2009;50(4):517-20.
13. Mlynarek ME, Peterson EL, Zarowitz BJ. Predicting unbound phenytoin concentrations in the critically ill neurosurgical patient. Ann Pharmacother. 1996;30(3):219-23.
14. Dager WE, Inciardi JF, Howe TL. Estimating phenytoin concentrations by the Sheiner-Tozer method in adults with pronounced hypoalbuminemia. Ann Pharmacother. 1995;29(7-8):667-70.
15. Pospisil J, Pelclová D. A graphical nomogram method for predicting toxic concentrations of unbound phenytoin. Int J Clin Pharmacol Ther. 1994; 32(3):122-5.
16. Rhoney DH, Leader WG, Chandler MH. Modified Michaelis-Menten equation for estimating unbound-phenytoin concentrations. Clin Pharm. 1993;12(12):913-7.
17. Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med. 1999;130(6):461-70.
18. von Winckelmann SL, Spriet I, Willems L. Therapeutic drug monitoring of phenytoin in critically ill patients. Pharmacotherapy. 2008;28(11):1391-400.
19. Patsalos PN, Berry DJ, Bourgeois BF, Cloyd JC, Glauser TA, Johannessen SI, et al. Antiepileptic drugs-best practice guidelines for therapetuic drug monitoring: a position paper by the subcommission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Epilepsia. 2008;49(7):1239-76.
20. Boucher BA, Wood GC, Swanson JM. Pharmacokinetic changes in critical illness. Crit Care Clin. 2006;22(2):255-71.
21. Brown AL, Sangha KS, Mueller EW, Kaur D, Keegan SP. Response to Characterization of unbound phenytoin concentrations in neurointensive care unit patients using a revised Winter-Tozer equation by Sean P. Kane, Adam P. Bress, and Eljim P. Tesoro. Ann Pharmacother. 2013;47(10): 1374-5.
22. Kane SP, Bress AP, Tesoro EP. Author response to Brown et al characterization of free phenytoin concentration in neurointensive care unit patients using a revised Winter-Tozer equation. Ann Pharmacother. 2013;47(12):1744.