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Lamotrigine Does Not Cause Weight Gain in Bipolar Patients: Presented at APA

By Danny Kucharsky

TORONTO, CANADA -- May 25, 2006 -- Lamotrigine is not associated with a significant mean increase in weight or body mass index (BMI) over 12 weeks of treatment, according to a study presented here at the American Psychiatric Association Annual Meeting (APA).

These results are consistent with previous findings, according to investigators Herndon P. Harding, Jr., MD, professor of psychiatry, Florida State University, Tallahassee, Florida, and colleagues.

The investigators suggested that the drug may be given to patients taking concomitant medications frequently associated with increased body weight, and that no additional weight gain might be expected.

"The main thing about lamotrigine is that it's weight-neutral. No harm, no foul," said Dr. Harding. "I'm very enthusiastic about (lamotrigine)."

The study was a post hoc analysis conducted from a prospective, open-label study of lamotrigine in 1,175 patients with bipolar I disorder designed to assess the rate of rash in patients with or without specific dermatological precautions. Lamotrigine was administered for 12 weeks, including a 5-week titration period (target dosage 200 mg/day).

Patients were assessed at screening/baseline and after 5 weeks and 12 weeks of lamotrigine therapy.

Results of the prospective study showed that baseline weight was significantly higher in patients taking concomitant valproate versus those without valproate (199.1 lbs. ± 49.07 lbs vs 184.7 lbs ± 47.53 lbs, P <.001), and was significantly higher in patients taking concomitant antipsychotics versus those not taking antipsychotics (192.7 lbs ± 47.31 lbs vs 186.1 lbs ± 48.48 lbs, P <.05).

Weight changes from baseline to week 12 (P >.05 for all group comparisons) were as follows:
· -0.2 lbs ± 6.82 lbs with valproate,
· 0.0 lbs ± 8.40 lbs without valproate,
· -0.4 lbs ± 7.99 lbs with antipsychotics
· 0.0 lbs ± 8.14 lbs without antipsychotics

There were no statistically significant changes in weight among the treatment groups.

There were also no statistically significant changes in BMI among treatment groups. BMI changes from baseline to week 12 (P >.05 for all group comparisons) were as follows:
· valproate, 0.0 ± 1.07
· without valproate, 0.0 ± 1.41
· with antipsychotics, -0.1 ± 1.34
· without antipsychotics, 0.0 ± 1.34

Dr. Harding noted that obese patients with and without concomitant valproate or antipsychotics experienced a small, nonsignificant decrease in weight after 12 weeks of lamotrigine treatment. He added that weight loss with long-term lamotrigine has been observed in obese volunteers and obese patients with bipolar I disorder.

Dr. Harding concluded that while patients gain weight with most antipsychotics, "there may be some hints that weight reduction may occur with lamotrigine." To investigate that hypothesis further, Dr. Harding is proposing a 6-month study of the subject.

This study was sponsored by GlaxoSmithKline Inc., Mississauga, Ontario, Canada.


[Presentation title: Weight and Body-Mass Index in Patients Receiving Open-Label Lamotrigine With or Without Concomitant Valproate, Antipsychotics, or Antidepressants. Abstract NR512]

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