title: Nighttime dosing assures postdistribution sampling for therapeutic drug monitoring of digoxin.
abstract: To study the appropriateness of phlebotomy for digoxin therapeutic drug monitoring (TDM) in outpatients, we conducted a retrospective chart review, a computer search of all previous TDM testing, and a questionnaire of all outpatients (n = 86) who had serum digoxin determinations between April 10 and April 28, 1992 (585 tests). In patients who took digoxin at the same time daily (40 patients, 300 tests), 52% of tests were performed on inappropriate samples drawn within 6 h of the last dose. No patient who took digoxin after 1700 had inappropriate tests. Phlebotomy for serum digoxin determinations before distribution of digoxin is complete is a common problem in outpatients, leading to clinically uninterpretable test results. Postdistribution sampling can be assured by nighttime dosing, and this recommendation has been implemented at our hospital.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Hospital of the University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Bernard
authors.forename: R L
authors.initials: RL
authors.lastname: Bowman
authors.forename: F A
authors.initials: FA
authors.lastname: Grimm
authors.forename: B A
authors.initials: BA
authors.lastname: Wolf
authors.forename: M B
authors.initials: MB
authors.lastname: Simson
authors.forename: L M
authors.initials: LM
authors.lastname: Shaw
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004077:Digoxin / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D004077:Digoxin