Lipitor is a medication used to treat high cholesterol levels in the blood. The previous dosage of Lipitor was changed due to important safety label changes made by the FDA [1]. In 2012, the FDA issued a drug safety communication regarding the use of cholesterol-lowering statin drugs, including Lipitor. The FDA warned that these drugs could increase the risk of developing diabetes, memory loss, and confusion. As a result, the FDA required changes to the safety labels of these drugs, including Lipitor, to reflect these risks [2].

The NEJM study [3] found that high doses of Lipitor were associated with an increased risk of developing diabetes. The study showed that patients taking high doses of Lipitor had a 37% increased risk of developing diabetes compared to those taking a lower dose. This finding may have contributed to the decision to change the previous dosage of Lipitor.

In summary, the previous dosage of Lipitor was changed due to safety concerns related to the use of cholesterol-lowering statin drugs, including Lipitor. The FDA required changes to the safety labels of these drugs to reflect the increased risk of developing diabetes, memory loss, and confusion. The NEJM study found that high doses of Lipitor were associated with an increased risk of developing diabetes, which may have contributed to the decision to change the previous dosage of Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-important-safety-label-changes-cholesterol-lowering-statin-drugs
[3] https://www.nejm.org/doi/10.1056/NEJMoa061894