public void PopulateMedicineDropdownList()
        {
            int centerId = Convert.ToInt32(Session["centerId"]);

            medicineDropDownList.DataSource     = manager.PopulateMedicineDropDownList(centerId);
            medicineDropDownList.DataTextField  = "MedicineName";
            medicineDropDownList.DataValueField = "Serial";
            medicineDropDownList.DataBind();
        }