There is no information in the provided sources regarding a minimum purchase requirement for Vascepa. Vascepa is a prescription medication used to treat high triglyceride levels in adults. It contains the active ingredient icosapent ethyl, which is a type of omega-3 fatty acid. The first source provided [1] lists the patent and exclusivity information for Vascepa, while the second source [2] discusses a legal dispute between Hikma Pharmaceuticals and Amarin over the supply of Vascepa's active pharmaceutical ingredient (API). The third source [3] is a filing by Amarin with the Securities and Exchange Commission discussing the company's financial results. None of these sources provide any information about a minimum purchase requirement for Vascepa. It is best to consult with a healthcare provider or pharmacist for information about prescription medication requirements.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/VASCEPA
[2] https://www.fiercepharma.com/pharma/hikma-pharmaceuticals-accuses-adversary-amarin-keeping-lock-api-suppliers-preventing-generic
[3] https://www.sec.gov/Archives/edgar/data/897448/000119312513432814/R13.htm