The cholesterol-lowering drug Lipitor, also known as atorvastatin, has undergone adjustments due to several factors, including patent expiration, generic competition, and dosage adjustments for improved safety and efficacy.

Firstly, the patent for Lipitor expired in November 2011 [1], allowing other pharmaceutical companies to produce and market generic versions of atorvastatin. This development led to a significant decrease in the price of the drug, making it more accessible to a larger patient population. Consequently, Lipitor's market share and sales decreased as patients and healthcare providers opted for the less expensive generic alternatives [1].

Secondly, the U.S. Food and Drug Administration (FDA) approved new dosage recommendations for atorvastatin in 2011 [2]. The FDA updated the drug's label to include new dosing options, allowing for more personalized treatment plans based on individual patient needs. These adjustments aimed to optimize the balance between the drug's efficacy in reducing low-density lipoprotein cholesterol (LDL-C) levels and its potential for adverse effects, particularly in relation to muscle and liver safety concerns [2][3].

In summary, Lipitor's adjustments were primarily driven by patent expiration and the subsequent introduction of generic atorvastatin, as well as updated FDA dosing recommendations to enhance the drug's safety and efficacy profile.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/LIPITOR>
[2] <https://www.ncbi.nlm.nih.gov/books/NBK430779/>
[3] <https://reference.medscape.com/drug/lipitor-atorvaliq-atorvastatin-342446>