Assessment of changes in both weight and frequency of use of medications for the treatment of gastrointestinal symptoms among clozapine-treated patients.

Clozapine has an unusual profile of adverse effects; among them, gastrointestinal (GI) side effects are important management concerns. The charts of patients in a state hospital who received clozapine for at least 3 months were reviewed. We compared the pre- and post-clozapine weights and changes in frequency and intensity of use of drugs prescribed for gastrointestinal symptoms for each subject (n = 99). There were statistically significant increases in the use of antacids (p < 0.02) and both bulk and non-bulk laxatives (p < 0.05, p < 0.03). Seventy-three percent of patients gained weight, of whom 27% gained over 10% body weight. This study confirms clozapine's association with weight gain, constipation, and upper GI symptoms. The literature concerning weight gain, and the mechanisms underlying GI adverse effects were reviewed.