Based on the information provided, the limitations on Vascepa coupon use can be summarized as follows:

1. Coupons may not be applicable for Medicare or Medicaid patients: According to the Vascepa website, Vascepa coupons cannot be used by patients who are eligible for reimbursement from any federal or state healthcare programs, such as Medicare, Medicaid, or any other state or federal healthcare program [1][2].

2. Coupons may not be used with other discounts or insurance coverage: The terms and conditions of Vascepa coupons state that they cannot be combined with any other discount, voucher, or offer, and are not valid with insurance of any kind [1][2].

3. Coupons have a maximum benefit limit: Vascepa coupons typically have a maximum benefit limit, after which the patient will be responsible for the full cost of the medication [1][2].

4. Coupons may not be available in all areas: The availability of Vascepa coupons may vary based on location and other factors, and not all pharmacies may accept them [1][2].

5. Coupons may not be used for refills: Vascepa coupons are typically only valid for a single prescription fill and may not be used for refills [1][2].

Sources:

[1] <https://www.drugpatentwatch.com/p/tradename/VASCEPA>
[2] <https://www.vascepa.com/>
[3] <https://www.goodrx.com/vascepa/medicare-coverage>