Study drug
Participants will receive D-sorbitol as the active drug and distilled water as the placebo. Participants will rinse with 25 mL of the study drug immediately before taking the sublingual asenapine tablet. Both D-sorbitol and distilled water will be kept clear and colorless to maintain blinding. During the study period, patients will be instructed to rinse their mouths by themselves at home or in the hospital ward. Afterwards, the patients will answer a multiple-choice questionnaire, which will be collected later.