Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1979-11-28
pubmed:abstractText
Phenytoin is a relatively insoluble weak acid, usually administered as the sodium salt. Bioavailability is dependent upon particle size and problems of generic inequivalence have therefore arisen, particularly in Scandinavia. The drug has a moderately large volume of distribution and is approximately 90% bound to plasma proteins. Clinically important displacement can be caused by bilirubin and several drugs, particularly sodium valproate, which is often combined with phenytoin. Displacement will lower the total serum concentration but will little affect the free drug concentration. The metabolism of phenytoin to the major metabolite, 5-(p-hydroxyphenyl)-5-(phenylhydantoin, is saturable, giving rise to a non linear dose-serum concentration relationship. Therefore, the dose range compatible with a therapeutic serum concentration is narrow within subjects, and monitoring serum concentrations is of particular value in dosage tailoring. In renal failure, the binding of phenytoin to plasma proteins is reduced and therefore a lower range of serum drug concentrations is compatible with therapeutic control. In liver disease, binding may also be impaired but delayed metabolism may occur in addition. During pregnancy the serum concentration may fall progressively as pregnancy advances, probably due to an increased rate of metabolism. Phenytoin readily crosses the placenta, and is metabolised rapidly by the neonate exposed in utero.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0312-5963
pubmed:author
pubmed:issnType
Print
pubmed:volume
4
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
153-69
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:articleTitle
Clinical pharmacokinetics of phenytoin.
pubmed:publicationType
Journal Article, Review