Blood phenytoin (diphenylhydantoin) concentrations were measured after each dosage change in 12 epileptic patients who were given increasing oral doses of phenytoin. In each of these patients a dosage increment beyond the dosage that produced a blood phenytoin level of 6-9 μg/ml. caused a disproportionately great increase in the blood concentration of drug. This effect might be expected if the ...

The commonly prescribed antiepileptic drug phenytoin has a narrow therapeutic range and wide interindividual variability in clearance explained in part by CYP2C9 and CYP2C19 coding variants. After finding a paradoxically low urinary phenytoin metabolite (S)/(R) ratio in subjects receiving phenytoin maintenance therapy with a CYP2C9*1/*1 and CYP2C19*1/*2 genotype, we hypothesized that CYP2C9 reg...

BACKGROUND Fosphenytoin, a phosphate ester prodrug of phenytoin, is metabolized to phenytoin in vivo. Phenytoin metabolites accumulate in renal insufficiency and cross-react in some phenytoin immunoassays. Our aim was to determine the accuracy of phenytoin immunoassays in renal patients treated with fosphenytoin. METHODS We measured phenytoin with HPLC and with the aca, ACS:180, TDx phenytoin...

A homogeneous substrate-labeled fluorescent immunoassay has been applied to the measurement of phenytoin concentrations in human serum. We coupled a fluorogenic enzyme substrate, galactosyl-umbelliferone, covalently to a derivative of phenytoin. Under assay conditions, this drug-substrate conjugate was nonfluorescent but became fluorescent upon hydrolysis catalyzed by bacterial beta-galactosida...

Increased concentrations of free phenytoin in serum, attributable to the displacement of this anticonvulsant by other drugs, e.g., valproic acid and salicylic acid, have been reported. We observed in vitro and in vivo displacement of phenytoin by the antibiotics ceftriaxone, nafcillin, and sulfamethoxazole. In vitro studies demonstrated statistically significant (P less than 0.05) increases in ...

In a cross-over study in a group of epileptic patients it was shown that replacement of the evening dose of an ordinary phenytoin preparation with the same phenytoin dose in a delayed-action preparation produced no significant change in the next morning's mean blood phenytoin concentration. However, replacement of the entire daily dose of an ordinary phenytoin preparation with the delayed-actio...

Background: Long term administration of antiepileptic drug phenytoin is reported to cause behavioral abnormalities mediated via oxidative stress. The effect of an antioxidant alpha lipoic acid (ALA) against phenytoin induced behavioral abnormalities was investigated. Methods: The study was carried out in albino wistar rats. The rats were divided into five groups of six animals each. Group 1 rec...

Phenytoin is one the most widely used antiepileptic drug among other antiepileptic drugs and is one of the vital medication for basic health system. Phenytoin has been used not only for convulsive but also for nonconvulsive treatment like arrhythmia, trigeminal neuralgia, digoxin toxicity, wound healing and in other disease conditions. With the wide range of usage of phenytoin, it has a collect...

Introduction: Interaction between drugs represents a major clinical concern for health care professionals and their patients. Patients affected by both type 2 diabetes and epilepsy may be prescribed pioglitazone and an anti-epileptic drug such as phenytoin  concurrently. The aim of this study was to consider the interaction of pioglitazone with phenytoin in an experimental model. According to t...

STUDY OBJECTIVE Oral phenytoin, intravenous phenytoin, and intravenous fosphenytoin are all commonly used for loading phenytoin in the emergency department (ED). The cost-effectiveness of each was compared for patients presenting with seizures and subtherapeutic phenytoin concentrations. METHODS A simple decision tree was developed to determine the treatment costs associated with each of 3 lo...