[Weight gain from atypical neuroleptics--an underreported adverse effect?].

After the introduction of the so-called "atypical neuroleptics" in the clinical experience a marked weight gain was frequently observed in patients treated with some of these agents. In this review the frequency, amount and conditions of weight gain during the medication with 'atypical' neuroleptics were evaluated. A comparison is limited by the different designs and recruitment procedures of the reviewed studies. The available data show that the frequency as well as the amount of weight gain is particularly high in patients treated with clozapine, olanzapine, and likely also quetiapine and zotepine. Moderate changes of weight have been observed in the treatment with risperidone and probably also with amisulpride, while ziprasidone seems to induce only clinically irrelevant weight changes. Weight gain most frequently occurs in the first weeks of treatment. Underweighted patients are at highest risk to gain weight. The underlying pathomechanism still remains widely unclear. The relative receptor affinities of the atypical antipsychotics for histamine H1 as well as their quotient of 5-HT2/D2 receptor affinity appear to be a correlate of weight gain. Furthermore, the induction of leptin secretion may have an important impact on weight gain in subjects treated with atypical neuroleptics. Although many questions concerning the conditions of weight gain remain unsolved, this side-effect has to be considered in the medication with many atypical neuroleptics, particularly in view of compliance in long-term treatment and possible medical complications.