Amitriptyline and its metabolite, nortriptyline, were measured in the plasma of eight humans for 96 hours following oral administration of a 75 mg dose of amitriptyline hydrochloride. Based on the 8 to 96 hour post dosing plasma concentration data, the terminal exponential half life of amitriptyline ± S.D. was 22.4±4.3 hr. Based on the 24 to 96 hour concentration data, the 'apparent' terminal half time of nortriptyline ± S.D. was 26.0±7.4 hours for seven subjects. For these same seven subjects the relative area under the plasma concentration time curve of nortriptyline ± S.D. was only 0.88±0.34 times that of amitriptyline. One subject whose apparent nortriptyline half time was 108 hours had a nortriptyline bioavailability 3.83 times that of amitriptyline. Average steady state plasma levels for 12 psychiatric patients who had received a 50 mg oral dose of amitriptyline three times a day for an average of 32 days could be predicted from the single dose plasma clearance of amitriptyline.
|Number of pages||10|
|Journal||Research Communications in Chemical Pathology and Pharmacology|
|Publication status||Published - Dec 1978|