(HealthDay News) — The antiepileptic drug zonisamide, at a dosage of 400mg per day, is associated with enhanced weight loss for obese patients when combined with diet and lifestyle counseling, but the incidence of adverse events is high, according to a study published online Oct. 15 in the Archives of Internal Medicine.

Kishore M. Gadde, M.D., from the Duke University Medical Center in Durham, N.C., and colleagues examined the efficacy and tolerability of zonisamide for enhancing weight loss in obese patients. Two hundred twenty-five obese participants (134 women) without diabetes mellitus were randomized to receive one year of daily dosing with placebo (74 participants), 200mg zonisamide (76 participants), or 400mg zonisamide (75 participants), as well as diet and lifestyle counseling by a dietician.

Two hundred eighteen participants provided follow-up assessments at one year. The researchers found that the change in body weight was −4.0 kg for placebo, −4.4 kg for 200mg of zonisamide, and −7.3 kg for 400mg of zonisamide. A weight loss of 5 percent or greater was achieved by 31.1 percent assigned to placebo, 34.2 percent assigned to 200mg of zonisamide (P = 0.72), and 54.7 percent (P = 0.007) of those assigned to 400mg of zonisamide. The corresponding numbers were 8.1, 22.4 (P = 0.02), and 32.0 percent (P < 0.001) for 10 percent or greater weight loss. There was a higher incidence of gastrointestinal, nervous system, and psychiatric adverse events with zonisamide versus placebo.

“Zonisamide at the daily dose of 400mg moderately enhanced weight loss achieved with diet and lifestyle counseling but had a high incidence of adverse events,” the authors write. “Hence, for treatment of obesity, the drug’s benefit-to-risk ratio needs thoughtful and cautious assessment.”

Several authors disclosed financial ties to the pharmaceutical industry. One author has been awarded several patents (in the name of his institution) involving zonisamide.

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