This bill allows a prescription drug plan (PDP) sponsor under the Medicare prescription drug benefit to share realized savings from an enrollee's switch to a lower-cost therapeutic alternative with the enrollee, in accordance with specified requirements. Among other requirements, the enrollee must have been taking the original prescription drug for at least two months and must have consulted with a physician before making the switch. PDP sponsors must share the savings in a tangible form that directly benefits the enrollee (e.g., a monetary rebate).