Mexiletine in treatment-resistant bipolar disorder.
BACKGROUND
The purpose of this study was to evaluate the efficacy and safety of mexiletine, a medication with antiarrhythmic, anticonvulsant and analgesic properties, in treatment-resistant bipolar disorder patients.


METHODS
Twenty subjects with rapid-cycling bipolar disorder who had failed to respond or were intolerant to lithium, valproic acid and carbamazepine were entered into the 6-week, open label study. Subjects were followed on a weekly basis for dosing of mexiletine, blood levels, and completion of the Hamilton Depression Rating Scale (HAM-D) and the Manic State Rating Scale (MSRS). "Burden of Mood Symptoms" (BMS) was calculated by combining scores for the HAM-D and MSRS.


RESULTS
Thirteen subjects (10 female, 3 male), mean age 41 years (S.D.=7.6), and mean duration of illness 20 years (S.D.=7.7) completed the study. The dose range of mexiletine was 200-1200 mg/day. Full response (>/=50% reduction in BMS) was seen in 46% of the subjects, and a partial response (25-49% reduction in BMS) in 15%. Of note, 5/5 subjects with a mixed or manic state demonstrated a full or partial response.


CONCLUSIONS
This study has an open label design, and a small number of subjects.


CONCLUSIONS
Mexiletine may be effective and safe in patients with highly treatment-resistant, chronic bipolar disorder. Randomized, controlled trials are required to confirm the current results.
Schaffer
A
A
Department of Psychiatry, Sunnybrook Health Science Center, 2075 Bayview Avenue, Room FG46, University of Toronto, Toronto, Canada.
Levitt
A J
AJ
Joffe
R T
RT
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000097:blood / Q000627:therapeutic use*; D001714:Bipolar Disorder / Q000188:drug therapy*; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008801:Mexiletine / Q000097:blood / Q000627:therapeutic use*; D008875:Middle Aged; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D008801:Mexiletine