Medicare Prescription Drug Price Negotiation Act of 2011 - Amends part D (Voluntary Prescription Drug Benefit Program) of title XVIII (Medicare) of the Social Security Act to direct the Secretary of Health and Human Services (HHS) to negotiate with pharmaceutical manufacturers the prices that may be charged to Medicare part D prescription drug plan (PDP) sponsors and MedicareAdvantage (MA) organizations for covered part D drugs for part D eligible individuals who are enrolled under a PDP or under an MA-Prescription Drug (MA-PD) plan.