A Pilot Trial of Tapering Antipsychotics for Patients in Remitted Psychosis Co-administering With N-Acetylcysteine

Trial procedure * Pretreatment: more instructions were delivered regarding the extent and the tempo of dose reduction, warning signal of relapse, timing to call for help if in need to resume rescue dose, and a shared decision-making process during tapering. Pre-treatment of NAC 1200 mg/d will be given for 1-2 weeks and then titrated up to 2400 mg/d to test tolerability. Patients will stay at either dose throughout the remaining of the course as preferable. * Dose tapering schedule: In the beginning, no more than one-quarter of the baseline antipsychotic dose will be reduced at a time. Patients need to be monitored every 4 weeks (or 1 month) by phone or in person. If they can maintain stabilized for 12 weeks (or 3 months) in a reduced dose, they can take next tapering of no more than one quarter of their current dose again, yielding 9/16 (3/4x3/4) of baseline dose. The subsequent dose reduction will be a reiteration of the previous step, cutting off one-quarter of the current dose following the formula (3/4) powered by n, rather than cutting off another 1/4 of the initial dose. The processes will be reiterated for 4 steps for one year. * Conditions during tapering: Noteworthily, when the patient is eligible to consider next dose reduction, he or she is empowered to take shared decision-making as they might opt to stay at their current dose for a more extended time for any reason. Patients can reach the study team during the course whenever they felt unsure if any relapse sign might be re-emerging. As needed use of benzodiazepines or hypnotics will be allowed to help control suspected signs of relapse. Patients will be supervised to stay at current dose for a longer term or even re-escalate to previous higher dose if any sign of suspected relapse re-emerges, and then will be closely monitored if their symptoms can be stabilized within 2 weeks. * Defining relapse: If a patient's recurrent psychotic symptoms cannot be controlled (any PANSS score \> 3 in P1, P2, P3, G5, or G9) within 2 weeks under an antipsychotic dose equal to their baseline dose, the patient will be designated as having a relapse. * Practicability of dosing: The actual dose taken would not always be precisely the number calculated by the formula (3/4)n, as it was impractical to cut off a quarter or even smaller piece of a tablet for daily dosing. Several versions of intermittent or irregular dosing schedules have been generated to meet the needs. * Extent of dose reduction: The percentage of doses reduced at a designated time point will be calculated by the following formula: \[1- (current dose)/(baseline dose)\]x100%.