Monitorización de niveles plasmáticos de fenitoína

phenytoin is a drug widely used at clinical practice for treatment of major epilepsy, partial and generalized tonic-clonic seizures and less frequently for other disorders such as cardiac arrhytmias and trigemin neuralgia. it is one of most frequently monitored the drugs by the clinical laboratory and it is due to several reasons: 1. it has got a narrow therapeutic interval with a low therapeutic index; 2. the relationship between the dose and the plasma level may be unpredictable due to great differences between patients; 3. the kinetic of metabolism is saturable in the therapeutic range, that means little increase of the dose may produce great rise of plasma levels. the indications of its monitoring are suspect of overdose or lack of compliance and presentation of seizures. in this work we have reviewed the pharmacological proprieties of phenytoin studying specially the pharmacokinetics, adverse reactions due to overdose and the analytical methods used for therapeutic drug monitoring at clinical laboratory.