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The rate of decline of diphenylhydantoin in human plasma
Author(s) -
Arnold Keith,
Gerber Nicholas
Publication year - 1970
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1970111121
Subject(s) - drug , half life , plasma concentration , chemistry , plasma clearance , human plasma , plasma levels , pharmacology , endocrinology , medicine , pharmacokinetics , chromatography
The rate of disappearance of diphenylhydantoin from plasma was studied in 70 healthy volunteers by giving them 100 mg. orally 3 times daily for 3 days and measuring the plasma diphenylhydantoin concentration for 4 consecutive days after the last dose of the drug. The mean plasma half‐life was 22.0 ± 9.0 hours and the difference between that of Negro and Caucasian males, 26.5 and 18.5 hours, respectively, was Significant. Dose dependency of the half‐life was demonstrated in 10 subjects studied. The decline in plasma diphenylhydantoin concentration in many subfects was not exponential and the disappearance of the drug from plasma was not always a first‐order process. The diphenylhydantoin half‐life in some subjects was shorter after long‐term administration than after short‐term administration of the drug. Saturation, autoinduction, or product inhibition, singly or in combination, of the drug‐metabolizing enzyme system are possible mechanisms involved in the dose dependency and nonexponential decline of plasma diphenylhydantoin concentration.