Twenty-three former heroin addicts who had been stabilized on 4 to 5 mg. of cyclazocine per day had their dossage increased to 10 to 30 mg. per day. These increases resulted in mild, transient side effects. The narcotic-blocking activity of cyclazocine was extended to 48 hours by a daily dose of 10 mg. and to 72 hours by 20 mg. A daily dose of 3O mg. increased its blocking activity at 48 hours but not at 72 hours.Abstract Teaser