Rate of elimination of tracer doses of phenytoin at different steady-state serum phenytoin concentrations in epileptic patients.

British journal of clinical pharmacology ·Vol. 1 ·No. 2 ·1974-04-00 ·Pages 155-61

Houghton GW, Richens A

Abstract

1 Serum phenytoin concentration, the serum half-life of a tracer dose of carbon-labelled phenytoin, and the ratio of the major metabolite of phenytoin to unchanged drug in urine (p-HPPH: DPH ratio) were measured in epileptic patients on chronic anticonvulsant therapy. 2 A significant correlation was found between serum phenytoin concentration and half-life, the slope of the regression line being dose dependent. 3 A significant negative correlation was found between serum phenytoin concentration and p-HPPH: DPH ratio. 4 Increasing the daily dose of phenytoin lead to a lengthening of the half-life and a reduction in the p-HPPH: DPH ratio. The reverse occurred on lowering the dose. 5 These changes indicate that phenytoin hydroxylation is saturable. 6 Difficulty in achieving a stable serum phenytoin concentration within the therapeutic range may result.

Authors & Affiliations

2 authors, click to expand affiliations / ORCID

Houghton G W

Department of Clinical Pharmacology, St Bartholomew's Hospital, London.

Richens A

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14 references, click to expand

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Article Info

Journal

British journal of clinical pharmacology

Abbr.

Br J Clin Pharmacol

ISSN

0306-5251

DOI

10.1111/j.1365-2125.1974.tb00225.x

Published

1974-04-00

Pages

155-61

Language

English

Region

England

NLM ID

7503323

PMCID

PMC1402453

External Links

PubMed source DOI: 10.1111/j.1365-2125.1974.tb00225.x PMC Full Text View journal details

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Rate of elimination of tracer doses of phenytoin at different steady-state serum phenytoin concentrations in epileptic patients.

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