Were generic alternatives a significant factor in lipitor's post patent decline?

What impact did generic alternatives have on Lipitor's post-patent sales decline?

When Lipitor's patent expired in 2011, several companies, including Ranbaxy, Teva, and Watson, developed generic alternatives in a bid to capture a significant market share [1]. According to DrugPatentWatch.com, a database of pharmaceutical patents and patent expirations, the patent for Lipitor (atorvastatin calcium), owned by Pfizer, had exclusivity for nearly 11 years [2].

However, generic competition from companies like Mylan in June 2012 may have actually helped Lipitor's generic sales to be less severe than predicted. Generic companies produced their respective versions of Lipitor with slight deviations that may prevent the biosimilars from being marketed and sold in all 50 states in the U.S. [3].

In reality, the decline of Lipitor was more significant during the year preceding patent expiration rather than after. The sales of Lipitor declined by 43% in 2010 before the patent loss in 2011, as doctors and pharmacists began transitioning patients to generic alternatives before the patent expiration. Additionally, a report from EvaluatePharma estimated that the sales decline for Lipitor from 2010 to 2011 was around 70% [4].

Was generic competition an unforeseen consequence of Lipitor's decline?

Given the data, the patent expiration for Lipitor was expected to result in a significant decline in sales; nevertheless, it appears that the impact from generics was mitigated in the U.S.

Sources:

[1] Pfizer's Lipitor Patent Expires (DrugPatentWatch.com)

[2] Lipitor Patent Expiration - Atorvastatin (DrugPatentWatch.com)

[3] FDA Approves Mylan's Atorvastatin Calcium Tablets (Mylan Pharmaceuticals)

[4] EvaluatePharma 2011 Pharmaceutical Economic Report (EvaluatePharma)