Long-term fluphenazine decanoate maintenance dosage requirements of chronic schizophrenic patients.

Forty-seven schizophrenic out-patients, who were satisfactorily maintained on a depot injection of fluphenazine decanoate, and who received the injection every 28 days, were progressively withdrawn from medication by increasing the time interval between injections while maintaining the amount of of drug per injection. The rate of reduction varied with each patient depending on various factors such as environmental stress considerations, and the patient's wishes. Finally three injections at 8-weekly intervals were given before complete withdrawal. The follow-up period was 23.7 months with a standard deviation of 1.9. A relapse rate of 80% was found, 25 patients relapsing during the withdrawal phase and 22 patients after the drug had been completely withdrawn.