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Audit of a monitoring service for free phenytoin


Peterson, GM and McLean, S and von Witt, RJ and Millingen, KS, Audit of a monitoring service for free phenytoin, British Journal of Clinical Pharmacology, 19, (5) pp. 693-697. ISSN 0306-5251 (1985) [Refereed Article]

DOI: doi:10.1111/j.1365-2125.1985.tb02697.x


This study assessed the value of introducing the measurement of free phenytoin levels in a public hospital. After publicising the availability and purpose of the assay, free phenytoin levels were determined either (a) on the doctor's request or (b) when the total level was requested and the patient's record showed evidence of factors predisposing to an elevated unbound fraction. Total phenytoin was measured by EMIT, and the unbound fraction by ultrafiltration at 37 degrees C using [14C]-phenytoin as a tracer. During a 9 month period, 70 free level determinations were performed on 46 patients. These comprised 20% of all phenytoin assays. The median free phenytoin fraction was 13.6% (range 9.3-28.6%). While total phenytoin levels were below the normal optimum range in 61% cases, free levels were probably therapeutic or above in 70% cases. Dosage adjustments were recommended on the basis of the free level, and were followed more often when the doctor had requested the free level assay (P less than 0.05). The results suggest that a free phenytoin level assay can improve the usefulness of therapeutic drug monitoring, particularly when the doctor understands the purpose of the assay.

Item Details

Item Type:Refereed Article
Research Division:Biomedical and Clinical Sciences
Research Group:Pharmacology and pharmaceutical sciences
Research Field:Clinical pharmacy and pharmacy practice
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Public health (excl. specific population health) not elsewhere classified
UTAS Author:Peterson, GM (Professor Gregory Peterson)
UTAS Author:McLean, S (Professor Stuart McLean)
UTAS Author:von Witt, RJ (Dr Richard von Witt)
ID Code:111097
Year Published:1985
Web of Science® Times Cited:9
Deposited By:College Office - CHM
Deposited On:2016-08-30
Last Modified:2016-08-30

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