Effect of Amantadine on Weight Gain Induced by Olanzapine

Bahk, Won Myong; Lee, Kyoung Uk; Chae, Jeong Ho; Lee, Won Hee; Jun, Taeyoun; Kim, Kwang Soo

Abstract

OBJECTIVE
Weight gain is a commonly encountered problem associated with atypical antipsychotics, especially olanzapine. To investigate the weight reducing effect of amantadine, we conducted an prospective open label study. METHODS: We started amantadine treatment in outpatients who had gained weight during olanzapine treatment (mean dose of 11.94 mg/day, mean weight gain of 6.33 kg). Data were collected at St. Mary's Hospital, College of Medicine, The Catholic University of Korea. The add-on treatment of amantadine was given at a mean dose of 161.9 mg/day with mean duration of administration for 110.2 day. Brief Psychiatric Rating Scale (BPRS), Extrapyramidal Symptom Scale were checked to evaluate the tolerability of amantadine. RESULTS: Before administration of amantadine, the mean dose of olanzapine was 11.94+/-4.58 mg and mean duration of administration was 123.1+/-174.6 days. Body weight and BMI during this period was significantly increased mean 6.33+/-4.45 kg (Z=-3.839, p<0.001), 4.94+/-0.75 (Z=-3.724, p<0.001) respectively. Amantadine was administered mean dose of 161.90+/-58.96 mg for mean 110.2+/-78.7 days. Body weight and BMI was decreased mean 0.96+/-3.44 kg, 0.71+/-2.7, respectively. There was no deterioration in psychiatric symptoms, as shown in BPRS score decrement and no adverse effects were reported. CONCLUSION: The present data suggests that amantadine does not significantly decrease weight gain experienced by some patients during olanzapine treatment and does not worse psychotic symptoms. Randomized placebo-controlled trial should be needed to confirm these findings.