Combating Dangerous Synthetic Stimulants Act of 2011 - Amends the Controlled Substances Act to include as a Schedule I controlled substance any material, compound, mixture, or preparation which contains 4-methylmethcathinone (Mephedrone) or 3,4-methylenedioxypyrovalerone (MDPV) or their salts, isomers, or salts of isomers.