As proven by Pfizer via its cholesterol-reducing drug Lipitor, medicine can command much value. In fact, the Lipitor patent became the most profitable patent ever produced. Today, that patent has expired, making it worthless. However, without the patent, Lipitor may have never been successful at all. We list the top five 2013 best-selling drugs next and how patents play a role in their success.

According to Genetic Engineering & Biotechnology News, the top five best-selling drugs and their 2013 sales are as follows.

  1. Humira – $10.659 billion.
  2. Remicade – $8.944 billion.
  3. Rituxan – $8.920 billion.
  4. Advair – $8.783 billion.
  5. Enbrel – $8.325 billion.

As noted, these drugs generate billions of dollars for big name pharmaceutical companies such as Amgen, GlaxoSmithKline, Johnson & Johnson, Merck & Co., Pfizer, and Roche. With the exception of Advair, all of the top-selling drugs still have patent protection. This patent protection will give these companies an edge over competition for a few more years at least. The patent for Humira will expire in 2016, while Remicade and Rituxan will expire in 2018. Enbrel was set to expire in 2012, but received an extension for another 16 years.

While Advair remains one of the top-selling drugs, its lack of patent protection is starting to show its effects. The first quarter of 2014 showed a 10% drop in market share, due to rivals hitting the market with similar medication. Patents afford pharmaceutical companies the ability to keep competition at bay. They make it difficult for generics and other similar drugs to enter the market so that consumers are limited in choices. Therefore, the pharmaceutical under patent gains the most market share. Although Advair is listed among the top five best-selling drugs, it’s only a matter of time before it falls off the list, which appears to be soon. In the meantime, GlaxoSmithKline has to develop other medications and build its patent portfolio to help bring up sales.