Monitoring clozapine: are fingerprick blood and plasma clozapine levels equivalent to arm venipuncture blood and plasma levels?
The objective of this pilot study was to determine whether fingerprick blood and plasma clozapine levels were equivalent to arm venipuncture blood and plasma levels for the purpose of therapeutic monitoring. A convenient sample of 10 outpatients from the Elgin Program of Assertive Community Treatment Team (PACT) participated in the study. Blood samples were obtained simultaneously from both the arm and finger in patients at steady state to measure clozapine levels. Each site provided a blood and plasma clozapine level, and they were compared. Clozapine levels from arm and finger sites were found to be equivalent in both blood and plasma. Although plasma clozapine levels were consistently greater than those in whole blood by a mean value of 27%, the plasma therapeutic threshold level (350-400 micro g/L) was considered an adequate target for monitoring. A fingerprick blood sample of 50 micro L was sufficient to measure clozapine levels accurately at steady state. We therefore concluded that fingerprick blood testing is as effective as the traditional arm venipuncture method in obtaining accurate clozapine levels. This procedure may provide certain benefits for the seriously mentally ill.
Goossen
Randolph B
RB
Program of Assertive Community Treatment, Elgin County, University of Western Ontario, St. Thomas, Ontario, Canada. rgoossen@wrha.mb.ca
Freeman
David J
DJ
Satchell
Anne Marie
AM
Urquhart
Bradley L
BL
D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000097:blood*; D001800:Blood Specimen Collection / Q000592:standards*; D003024:Clozapine / Q000097:blood*; D016903:Drug Monitoring / Q000592:standards*; D005260:Female; D005385:Fingers; D006801:Humans; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy / Q000592:standards*; D010865:Pilot Projects
D014150:Antipsychotic Agents; D003024:Clozapine