File(s) not publicly available
Audit of a monitoring service for free phenytoin
journal contribution
posted on 2023-05-18, 21:54 authored by Gregory PetersonGregory Peterson, Stuart McLeanStuart McLean, von Witt, RJ, Millingen, KSThis 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.
History
Publication title
British Journal of Clinical PharmacologyVolume
19Issue
5Pagination
693-697ISSN
0306-5251Department/School
College Office - College of Health and MedicinePublisher
Blackwell Publishing LtdPlace of publication
United KingdomRepository Status
- Restricted