Biomaterial Database

Comparative study of bioavailabilities of different phenytoin preparations. 1982

Y Fukuyama, and H Kitahara, and T Goto

A comparative study of the serum phenytoin (PHT) concentration levels during the treatment with different PHT preparations (powders or tablets) manufactured by two Japanese pharmaceutical companies gave the following results: 1) The serum PHT concentration levels (S in microgram/ml) of children (aged 7-11) who were taking Company A's powder and phenobarbital were less than 2.0 microgram/ml in 21 out of 24 (87.5%) cases without correlation with the dosage (D in mg/kg). The levels in 19 children of the same ages taking Company A's tablets showed significant correlation with the dosage, and the regression line was S = 1.9D - 2.65 (r = 0.86). 2) In 33 cases, previously administered Company A's powder was substituted with different PHT preparations of the same or a lesser dosage; Company A's tablet in group I; powderized Company A's tablet in group II: Company B's powder in group III; and Company B's tablet (solid or powderized) in group IV. In all cases, the PHT S/D ratio increased after the substitution and the mean increase +/- SD was 1.3 +/- 1.2 (p less than 0.001) for group I, 1.0 +/- 0.1 (p less than 0.001) for group II, 0.45 +/- 0.1 (p less than 0.005) for group III, and 1.6 +/- 0.4 (p less than 0.015) for group IV. 3) Tested in five patients using three specially prepared phenytoin powders with different particle sizes clearly demonstrated the fact that the smaller the PHT particle, the higher the PHT S/D ratio. 4) It was suggested that the factors other than particle size of the drug should be taken into consideration in the interpretation of different bioavailabilities of different PHT preparations.

UI	MeSH Term	Description	Entries
D010672	Phenytoin	An anticonvulsant that is used to treat a wide variety of seizures. It is also an anti-arrhythmic and a muscle relaxant. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. The mechanism of its muscle relaxant effect appears to involve a reduction in the sensitivity of muscle spindles to stretch. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs.	Diphenylhydantoin,Fenitoin,Phenhydan,5,5-Diphenylhydantoin,5,5-diphenylimidazolidine-2,4-dione,Antisacer,Difenin,Dihydan,Dilantin,Epamin,Epanutin,Hydantol,Phenytoin Sodium,Sodium Diphenylhydantoinate,Diphenylhydantoinate, Sodium
D011208	Powders	Substances made up of an aggregation of small particles, as that obtained by grinding or trituration of a solid drug. In pharmacy it is a form in which substances are administered. (From Dorland, 28th ed)	Powder
D002648	Child	A person 6 to 12 years of age. An individual 2 to 5 years old is CHILD, PRESCHOOL.	Children
D002675	Child, Preschool	A child between the ages of 2 and 5.	Children, Preschool,Preschool Child,Preschool Children
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004827	Epilepsy	A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313)	Aura,Awakening Epilepsy,Seizure Disorder,Epilepsy, Cryptogenic,Auras,Cryptogenic Epilepsies,Cryptogenic Epilepsy,Epilepsies,Epilepsies, Cryptogenic,Epilepsy, Awakening,Seizure Disorders
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000284	Administration, Oral	The giving of drugs, chemicals, or other substances by mouth.	Drug Administration, Oral,Administration, Oral Drug,Oral Administration,Oral Drug Administration,Administrations, Oral,Administrations, Oral Drug,Drug Administrations, Oral,Oral Administrations,Oral Drug Administrations
D000293	Adolescent	A person 13 to 18 years of age.	Adolescence,Youth,Adolescents,Adolescents, Female,Adolescents, Male,Teenagers,Teens,Adolescent, Female,Adolescent, Male,Female Adolescent,Female Adolescents,Male Adolescent,Male Adolescents,Teen,Teenager,Youths
D001682	Biological Availability	The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.	Availability Equivalency,Bioavailability,Physiologic Availability,Availability, Biologic,Availability, Biological,Availability, Physiologic,Biologic Availability,Availabilities, Biologic,Availabilities, Biological,Availabilities, Physiologic,Availability Equivalencies,Bioavailabilities,Biologic Availabilities,Biological Availabilities,Equivalencies, Availability,Equivalency, Availability,Physiologic Availabilities