title: Plasma and erythrocyte levels of tricyclic antidepressants in depressed patients.
abstract: Plasma and red blood cells (RBCs), amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyl doxepin levels were measured in depressed inpatients during steady-state kinetics. A strong positive correlation between the drug levels in plasma and RBCs was found for amitriptyline, nortriptyline, desipramine, and desmethyl doxepin. However, at a given plasma level, up to a 6-fold interindividual variation in the RBC drug levels was found. The correlations between plasma and RBC imipramine and doxepin levels were low. The interindividual variation in the RBC-plasma tricyclic level ratios was large enough to warrant further clinical studies on the relationship between efficacy and pharmacokinetics of tricyclic antidepressants.
mesh_terms: D000328:Adult; D000639:Amitriptyline / Q000097:blood; D000929:Antidepressive Agents, Tricyclic / Q000097:blood*; D001702:Biopharmaceutics; D002986:Clinical Trials as Topic; D003863:Depression / Q000097:blood*; D003891:Desipramine / Q000097:blood; D004316:Doxepin / Q000097:blood; D004912:Erythrocytes / Q000032:analysis*; D006801:Humans; D007099:Imipramine / Q000097:blood; D008875:Middle Aged; D009661:Nortriptyline / Q000097:blood
chemical_list: D000929:Antidepressive Agents, Tricyclic; D004316:Doxepin; D000639:Amitriptyline; D009661:Nortriptyline; D007099:Imipramine; D003891:Desipramine