Effect of amantadine on weight gain during olanzapine treatment

Patients treated with olanzapine may gain weight, especially in the first months of therapy. Amantadine (100-300 mg/day) was started in 12 patients having a mean weight gain of 7.3 kg during olanzapine treatment. The patients' weight stabilised and over 3-6 months they lost an average of 3.5 kg. No clinical deterioration occurred and no adverse effects were reported. These observations merit confirmation in randomised, controlled trials.