Therapeutic window of lamotrigine for mood disorders: a naturalistic retrospective study.
BACKGROUND
Lamotrigine is widely used for mood disorders including bipolar disorder and major depression, but its therapeutic levels have yet to be determined. This study was conducted to investigate the hypothesis that lamotrigine may have a therapeutic window for mood disorders.


METHODS
25 patients with mood disorders received lamotrigine for more than one year during which time plasma lamotrigine levels were measured at least once. Their mental state was retrospectively and regularly but blindly assessed using the Clinical Global Impression-Severity (CGI-S) scale. In order to investigate our hypothesis, we depicted the relationship between the last lamotrigine levels and the last CGI scores in 25 patients. If any, the potential therapeutic window was further investigated.


RESULTS
The relationship between the last lamotrigine levels and the last CGI scores in the 25 patients indicated the presence of a therapeutic window of lamotrigine from 5 to 11 μg/mL. The repeated measures of ANOVA reached a significant tendency of the effects of lamotrigine levels within 5-11 μg/mL on better CGI-S scores, and the CGI-S scores at the last observation of the 15 patients whose lamotrigine levels were within 5-11 μg/mL were significantly better than those of 10 patients whose lamotrigine levels were not within 5-11 μg/mL.


CONCLUSIONS
These findings suggest that lamotrigine may have a therapeutic window for patients with mood disorder from 5 to 11 μg/mL.
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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Y
Katayama
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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T
Terao
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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K
Kamei
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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K
Hatano
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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Kohno
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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M
Makino
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
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Y
Mizokami
Department of Neuropsychiatry, Oita University Faculty of Medicine, Yufu, Japan.
K
K
Kodama
Department of Clinical Pharmacy, Oita University Faculty of Medicine, Yufu, Japan.
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H
Itoh
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016903:Drug Monitoring; D018691:Excitatory Amino Acid Antagonists / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000097:blood* / Q000188:drug therapy*; D011569:Psychiatric Status Rating Scales; D012189:Retrospective Studies; D014227:Triazines / Q000097:blood* / Q000627:therapeutic use*
D018691:Excitatory Amino Acid Antagonists; D014227:Triazines; D000077213:Lamotrigine