According to the sources provided, Lipitor is a prescription medication used to lower cholesterol levels in the blood. The drug contains the active ingredient atorvastatin calcium and is available in tablet form.

Regarding the expiration date of Lipitor, it is essential to understand that all drugs have an expiration date, which is determined by the manufacturer and indicates the time during which the drug is expected to remain stable and effective. However, the expiration date does not necessarily mean that the drug is no longer safe or effective after that date.

A study cited in an NPR article [3] found that many drugs, including Lipitor, can remain potent for years beyond their expiration date. However, it is important to note that this study does not necessarily apply to all drugs, and the potency of a drug can depend on various factors, such as storage conditions, the type of drug, and the dosage form.

According to Harvard Health Publishing [2], expired drugs may lose some of their potency over time, but they are unlikely to be harmful. However, it is recommended to dispose of expired drugs and obtain a new prescription to ensure the drug's effectiveness and safety.

In conclusion, while Lipitor and other drugs may remain potent beyond their expiration date, it is recommended to obtain a new prescription to ensure the drug's effectiveness and safety. It is important to follow the advice of a healthcare professional regarding the use and storage of prescription medications.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.health.harvard.edu/staying-healthy/drug-expiration-dates-do-they-mean-anything
[3] https://www.npr.org/sections/health-shots/2017/07/18/537257884/that-drug-expiration-date-may-be-more-myth-than-fact