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The effect of age on the plasma levels of amoxapine and its major metabolite in depressed patients
Author(s) -
Aoba Anri,
Yamaguchi Noboru,
Tsuneizumi Tomohiro,
Chishima Tatsuo,
Tsuzura Michinori,
Sakai Takashi,
Negishi Kyoichiro,
Tagaki Hiroyuki,
Hasegawa Kazuo,
Kitani Kenichi,
Shibata Makiko
Publication year - 1987
Publication title -
international journal of geriatric psychiatry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 129
eISSN - 1099-1166
pISSN - 0885-6230
DOI - 10.1002/gps.930020407
Subject(s) - metabolite , chemistry , medicine , endocrinology , plasma levels , plasma concentration , excretion
Twenty‐eight depressed patients receiving amoxapine with ages ranging from 21 to 68 years (male 12, female 16) were studied in order to clarify the age effect on plasma levels of amoxapine and its major active metabolite, 8‐OH amoxapine. Plasma amoxapine levels were determined by both radioreceptor assay (RRA) and gas liquid chromatography (GLC). Plasma levels of 8‐OH amoxapine were also determined by GLC. A highly significant correlation was found for plasma levels of amoxapine determined by RRA and GLC ( r = 0.88, p < 0.001). There was no significant correlation between the amoxapine daily dose (mg/kg) and its plasma levels determined either by RRA or GLC. The ratios of plasma amoxapine level by RRA and GLC to daily dose significantly increased with advancing age ( p < 0.05) and a significant positive correlation was also found between the ratio of plasma level of 8–OH amoxapine to daily dose and the age of the patients ( p < 0.01), suggesting that the plasma 8‐OH amoxapine levels were more strongly affected by age than the parent drug. These results indicate that the metabolism of amoxapine in the liver decreases with age as well as that of other tricyclic antidepressants reported previously. The higher correlation of 8‐OH amoxapine with patient's age may be mainly due to its renal excretion which may also decrease with age.