IRCT2015060520024N2 IRCT 2015-07-06 Vice chancellor for research, Tehran University of Medical Sciences The effect of Dextromethorphan premedication on cough, pain, anxiety, procedure duration and sedation during fiber optic bronchoscopy. The effect of Dextromethorphan premedication on cough, pain, anxiety, procedure duration and sedation during fiber optic bronchoscopy: a randomized, double-blind, placebo-controlled trial 2015-06-01 anticipated 66 Complete https://irct.ir/trial/17768 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Diagnostic, Other design features: Sixty-six patients scheduled for FOB in Imamkhomeini hospital complex will be randomly allocated into two groups according to four blocks (AABB) randomization system. Six states of AABB, ABAB, ABBA, BBAA, BABA, and BAAB will be recorded in six different cards, and then these cards will be mixed together. Consequently, the cars will be selected for 18 times and the order of letters will be registered. The A and B label will be sealed to the researcher and the patients. 2-3 Respiratory disorder, unspecified. Intervention 1: Ninety minutes before FOB, 90 mg (30 cc) of syrup Dextromethorphan, manufactured by kharazmi pharmaceutical co, code:IRC-1228087158,. Intervention 2: Ninety minutes before FOB, 30cc sucrose syrup.