title: The measurement of plasma levels of tricyclic antidepressant drugs.
abstract: A double-isotope derivative dilution procedure for measuring plasma levels of Nortriptyline is described. The assay is specific, sensitive, precise and reproducible. Studies on the variation in steady-state plasma levels are described on a fixed oral dosage of nortriptyline. Between individual variations in steady-state plasma levels are large. Between day within individual variation is 15-20%. Dosage regime, time of blood sampling after last oral dose and the method of blood handling are unlikely to affect the steady-state plasma levels. Within an individual, the oral dose, duration of treatment and concomitant drug treatment are all important determinants of the steady-state plasma level.
mesh_terms: D001793:Blood Preservation; D001800:Blood Specimen Collection; D002250:Carbon Radioisotopes; D006801:Humans; D009661:Nortriptyline / Q000008:administration & dosage / Q000097:blood*; D013997:Time Factors; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D014316:Tritium; D009661:Nortriptyline