Factors influencing nortriptyline steady-state kinetics: plasma and saliva levels.
Proportionality between dose and steady-state nortriptyline (NT) plasma levels was found both during initial treatment and after long-term treatment (years) within the NT Plasma level range of 20 to 296 ng/ml. There were day-to-day variations of 10% to 20% (coefficient of variation) but no systematic changes in plasma levels over time. A significant age variation in NT plasma levels was found in 116 patients. Patients over 70 yr of age (n = 23) had higher levels than other age groups (p < 0.001) dose corrected; p < 0.0001 dose and weight corrected). It was found that during episodes of acute inflammatory diseases NT steady-state plasma levels rose after a change in sedimentation rate. Our data show that the use of saliva rather than plasma in therapeutic drug level monitoring of NT cannot be recommended because the saliva/plasma ratio varied both intra- and interindividually by factors of from 2 to 4.
D000328:Adult; D000367:Age Factors; D000368:Aged; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009661:Nortriptyline / Q000097:blood / Q000378:metabolism*; D012463:Saliva / Q000032:analysis*; D013997:Time Factors
D009661:Nortriptyline