[en] Thirty-one patients with endogenous, endoreactive or exogenous depression, usually associated with anxiety, participated in a randomized, double-blind controlled study designed to compare the therapeutic efficacy and tolerance of butriptyline (75 mg per day for 6 weeks), given either in its regular form or as a sustained-release formulation. Patients in one group received 3 daily doses of 25 mg butriptyline; those in the other received a single 75 mg daily dose at bedtime of the sustained-release formulation plus 2 doses of placebo during the day. All patients were assessed by means of 5 psychometric scales (Hamilton, BPRS, NOSIE, Cattell and CGI) before the start of therapy, after 3 weeks and after 6 weeks. Biological parameters (blood, liver, ECG and EEG) were also controlled. The results of the psychometric assessment showed that butriptyline, in both dosage forms, was consistently effective and produced marked improvement in rating scores in the majority of the patients. The few side-effects reported were mild and transient, and were mostly of the classical anticholinergic type. The sustained-release form, given once daily, provided simplicity and convenience of administration, resulting in improved patient acceptance and improvement in sleep disturbances.