While it is common to find psychotropic medication prescribed to children diagnosed with autism-spectrum disorders, they can have serious side effects and the data supporting their use is not overwhelmingly strong (long term prognosis for success for these medications is entirely unknown). Because of the methodology used in these studies, we aren't able to predict ahead of time who is a good candidate for which medication. This results in the decision making about the medications being essentially a very long trial and error process (and, in many cases, children do better off of medication altogether). My recommendation is that you focus your energy in examining the clinical programming your grandson is receiving. These behavior problems can reliably be treated through behavior analytic intervention. Make sure he is receiving strong educational and behavior analytic services, where the professionals will explain the interventions to you and show you the data evaluating your grandson's progress. It is often an excellent and reasonable long-term goal to have the child off of psychotropic medication altogether once he or she has started responding to behavioral intervention.