Yes.  Medicare Part D prescription drug coverage is voluntary and you can use a Drug Discount Coupon or Drug Discount Card to purchase your medications instead of your Medicare Part D plan coverage.  Likewise, if you find a pharmacy offering discounted prices or prices less than your Part D coverage, then you are permitted buy your medications without using your Medicare Part D prescription drug plan (but, you may need to specifically ask the pharmacist to use the pharmacy's discounted price rather than your Medicare Part D plan coverage).

However, there are a few things to consider when purchasing your medications outside of your Medicare Part D plan:

• You cannot combine drug discounts with your Medicare Part D coverage.
  
  A drug discount program (discount card or discount coupon) will not work together with a Medicare Part D plan, so you cannot use a drug discount program together with your Medicare Part D coverage for added savings.
  
  
  
• Drug Manufacturer Coupons are not the same as Drug Discount Coupons --- and you CANNOT use a Drug Manufacturer Coupon if you are eligible for Medicare.
  
  Often you will hear a television commercial for a new brand-name drug offering a short-term discount coupon for the new drug.  However, if you are eligible for Medicare you CANNOT use a Drug Manufacturer's Coupon based on federal anti-kickback laws.
  
  You may even notice the "fine print" on the coupon stating something such as: "This Card is not valid for prescriptions that are eligible to be reimbursed, in whole or in part, by Medicaid, Medicare or other federal or state healthcare programs (including any state prescription drug assistance programs and the Government Health Insurance Plan available in Puerto Rico [formerly known as “La Reforma de Salud”])."
  
  As noted in a government report: “Pharmaceutical manufacturers offer copayment coupons to reduce or eliminate the cost of patients’ out-of-pocket copayments for specific brand-name drugs.  The anti-kickback statute prohibits the knowing and willful offer or payment of remuneration to a person to induce the purchase of any item or service for which payment may be made by a Federal health care program [i.e., Medicare].  Manufacturers may be liable under the anti-kickback statute if they offer coupons to induce the purchase of drugs paid for by Federal health care programs, including Medicare Part D.”
  
  In addition, you may notice that a pharmaceutical company's website will provide a Pharmaceutical Assistance Program (PAP) offering drug discounts to people in economic need.  However, you will usually see the PAP's disclaimer that the discount is not available for people who are eligible for Medicare or people who already have drug coverage.  For instance, you might read: "Patient must [n]ot have private or public prescription coverage [in order to be eligible for the program]."