 E.3.4.Mechanisms of drug placebo distribution: The anticipated number of patients to be enrolled in this study in each participating center has been calculated according to previous records of the center. According to this number, the drugplacebo distribution will be done. The responsible group for the blindness of the study and distribution of the drug will be the pharmacist in each center and heshe will keep codes for each patient not to be broken except at the end of the study. The pharmacist is also responsible for dispensing the drug and placebo packets to the patients as monthly supplies and should inform the patient guardian to bring the empty packs before receiving the new medication to ensure compliance of the patients to the study. 