A COMPARISON OF PLASMA PHENYTOIN LEVEL DETERMINATIONS BY EMIT AND GAS-LIQUID-CHROMATOGRAPHY IN PATIENTS WITH RENAL-INSUFFICIENCY

  • 1 January 1980
    • journal article
    • research article
    • Vol. 2  (4) , 427-430
Abstract
Monitoring the blood levels of antiepileptic drugs (AED) is of value in the clinical management of epileptic patients. The plasma concentrations of AED determined by EMIT and GLC assays were compared and a group of patients (n = 22) in whom the EMIT values for phenytoin were up to 3 times higher than those obtained by GLC were identified. All these patients were oliguric with various degrees of azotemia, most of them undergoing weekly hemodialysis. The ratio of EMIT over GLC was 2.0 in 14 patients, 2.5 in 5 patients, and .apprx. 3.0 in 3 patients. These ratios remained relatively constant during repeated determinations over several months. The magnitude of difference between EMIT and GLC values (.mu.g/ml) was not related to the degree of azotemia. The discrepancy remained unchanged when various modifications of EMIT and GLC techniques were used. When phenytoin was added in vitro to plasma from nonepileptic oliguric azotemic patients, the measured phenytoin values were close to and not higher than the target values by either methodology. When monitoring phenytoin blood levels in epileptic patients with renal insufficiency, there is a discrepancy between phenytoin values assayed by GLC and EMIT.

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