Systematic approach to a dosage regimen for phenytoin based on one-point, steady-state plasma concentration

E. Nakashima, R. Matsushita, H. Kido, M. Nakamura, M. Asahi, F. Ichimura

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A systematic approach to individualizing the phenytoin (PHT) dose from a previous dose (D) and steady-state concentration (C(ss)) pair was established by the combined use of two methods based on recently reported population pharmacokinetic parameters. This system applies the Michaelis-Menten equation to the initial data pair (D(t)-C(ss1)) and solves for (a) maximum metabolic rate constant (V(max)) assuming the population mean for the Michaelis constant (K(m)) (method 1), and (b) K(m) assuming the population mean for V(max) (method 2). The derived estimates of V(max) and K(m) are then put through a series of filters, which results in the selection of method 1 and/or method 2 or allocation of a third category that needs further evaluation. A simulation study was performed to find a series of filters. The presented approach was applied retrospectively to the patients' data of 35 sets. Accurate predictions of the C(ss) error within 5 μg/ml were obtained in 84% of the 25 cases, and in 30% of the 10 cases excluded. This systematic approach gives better prediction performance in mean error, mean absolute error, and root mean square error than a Bayesian feedback method.

Original languageEnglish
Pages (from-to)12-18
Number of pages7
JournalTherapeutic Drug Monitoring
Volume17
Issue number1
Publication statusPublished - 1995
Externally publishedYes

Fingerprint

Phenytoin
Plasmas
Pharmacokinetics
Mean square error
Rate constants
Population
Dilatation and Curettage
Bayes Theorem
Feedback

Keywords

  • Dosage regimen
  • Graphic estimation
  • Phenytoin
  • Systematic approach

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Health, Toxicology and Mutagenesis
  • Pharmacology (medical)
  • Public Health, Environmental and Occupational Health
  • Pharmacology
  • Toxicology

Cite this

Nakashima, E., Matsushita, R., Kido, H., Nakamura, M., Asahi, M., & Ichimura, F. (1995). Systematic approach to a dosage regimen for phenytoin based on one-point, steady-state plasma concentration. Therapeutic Drug Monitoring, 17(1), 12-18.

Systematic approach to a dosage regimen for phenytoin based on one-point, steady-state plasma concentration. / Nakashima, E.; Matsushita, R.; Kido, H.; Nakamura, M.; Asahi, M.; Ichimura, F.

In: Therapeutic Drug Monitoring, Vol. 17, No. 1, 1995, p. 12-18.

Research output: Contribution to journalArticle

Nakashima, E, Matsushita, R, Kido, H, Nakamura, M, Asahi, M & Ichimura, F 1995, 'Systematic approach to a dosage regimen for phenytoin based on one-point, steady-state plasma concentration', Therapeutic Drug Monitoring, vol. 17, no. 1, pp. 12-18.
Nakashima, E. ; Matsushita, R. ; Kido, H. ; Nakamura, M. ; Asahi, M. ; Ichimura, F. / Systematic approach to a dosage regimen for phenytoin based on one-point, steady-state plasma concentration. In: Therapeutic Drug Monitoring. 1995 ; Vol. 17, No. 1. pp. 12-18.
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