human psychopharmacology Hum Psychopharmacol Clin Exp 2004; 19: 37–40. Published online 30 January 2003 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/hup.477 Nizatidine for the treatment of patients with quetiapine-induced weight gain Murad Atmaca 1 *, Murat Kuloglu 1 , Ertan Tezcan 1 , Bilal Ustundag 2 and Nulufer Kilic 1 1 Firat University, School of Medicine, Department of Psychiatry, Elazig, Turkey 2 Firat University, School of Medicine, Department of Clinical Biochemistry, Elazig, Turkey It has been reported that nizatidine may reduce weight gain in schizophrenic patients on olanzapine treatment. Leptin has been reported to be associated with antipsychotic-induced weight gain. Thus, the purpose of the study was to evaluate whether nizatidine might be useful for the treatment of quetiapine-induced weight gain. Among the patients on the quetia- pine monotherapy, 47 participated in the study for the two and half months of the open-label screening period. However, 28 patients who gained considerable weight in this period entered the 8-week, double-blind and placebo-controlled phase. These patients were randomly divided into two groups; quetiapine plus nizatidine (group I) and quetiapine plus placebo (group II) for the 8-week double-blind phase. The patients were evaluated at the baseline and at week 8 with respect to the positive and negative syndrome scale, body mass index, weight and serum leptin levels. The mean weight and leptin levels exhibited modest increases in both groups for the open-label screening period. In the double-blind period, in group I, a minimal, but not statistically significant, decrease in weight was observed, with a mean of 1.0  0.6 kg. The weight increased in group II. The leptin levels decreased by a mean of 0.6  0.6 ng/ml in group I, and increased by 1.0  0.9 ng/ml in group II. At evaluation at week 8, a trend toward statistical significance in the mean serum leptin levels between groups was detected. The results suggest that nizatidine treatment may stop but not reduce the weight gain and is correlated with leptin levels in patients with schizophrenia on quetiapine treatment. Copyright # 2003 John Wiley & Sons, Ltd. key words — leptin; nizatidine; quetiapine; weight gain INTRODUCTION Weight gain is a common adverse effect of a variety of psychotropic drugs such as lithium, tricyclic antide- pressants and antipsychotics (Berken et al., 1984; Kraus et al., 1999; Atmaca et al., 2002c). Although both classical and atypical antipsychotics are known to induce weight gain (Brady, 1989; Osser et al., 1999), atypical antipsychotics, especially olanzapine and clozapine appear to have greater potential to induce weight gain (Allison et al., 1999). The factors influencing body weight in patients using an antipsy- chotic are probably complex, despite the fact that the effects of several neurotransmitter systems including serotonergic, dopaminergic and histaminergic sys- tems may contribute to weight gain (McIntyre et al., 2001). Leptin has recently attracted considerable interest in a variety of psychiatric disorders and psy- chotropic drug use (Kraus et al., 2001; Atmaca et al., 2002a,b,c,f ). Leptin administration reduced food intake and weight, suggesting its role on weight regu- lation (Halaas et al., 1995). Furthermore, an interac- tion has been shown between leptinergic and serotonergic systems in the central nervous system (Liebowitz and Alexander, 1998). The 5-HT 2C recep- tor blockade effect of antipsychotics has been dis- cussed as a possible cause of increase in food intake and related weight gain (McIntyre et al., 2001). Olan- zapine and clozapine have a strong affinity to seroto- nin and histamine receptors (5-HT 2a , 5-HT 2c and H 1 ) which are associated with weight gain (Stahl, 1998). The weight gain induced by clozapine and olanzapine has been reported to be associated with an increase in the leptin levels (Kraus et al., 1999). In our previous study, it was found that quetiapine has a modest effect on weight and is correlated with leptin levels (Atmaca et al., 2002e). To the best of our knowledge, this is the Received 30 September 2002 Copyright # 2003 John Wiley & Sons, Ltd. Accepted 16 December 2002 * Correspondence to: Dr M. Atmaca, Firat (Euphrates) Universitesi, Firat Tip Merkezi, Psikiyatri Anabilim Dali, 23119 Elazig, Turkey. Tel: (90) 424 233 3555/2282. Fax: (90) 424 238 7688. E-mail: matmaca_p@yahoo.com