Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the body. According to Drug Patent Watch [1], Lipitor is a brand-name drug and has been available since 1996. It is a widely used medication, and it is important to monitor its effects on the liver.

The National Center for Biotechnology Information [2] states that statins, including Lipitor, can cause liver damage in some patients. Therefore, it is recommended to monitor liver function through regular blood tests. The frequency of liver tests may vary depending on the patient's medical history, age, and other factors. The doctor may perform a liver function test before starting the medication and then repeat it after a few weeks to check for any changes.

The National Health Service [3] advises that patients taking Lipitor should have their liver function tested before starting the medication and then every six to 12 months thereafter. However, the frequency of testing may vary depending on the patient's individual circumstances. If a patient experiences any symptoms of liver problems, such as yellowing of the skin or eyes, dark urine, or abdominal pain, they should seek medical attention immediately.

In conclusion, Lipitor can cause liver damage in some patients, and it is important to monitor liver function through regular blood tests. The frequency of liver tests may vary depending on the patient's medical history, age, and other factors. Patients taking Lipitor should have their liver function tested before starting the medication and then every six to 12 months thereafter, but the frequency of testing may vary depending on the patient's individual circumstances. If a patient experiences any symptoms of liver problems, they should seek medical attention immediately.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/books/NBK548236/
[3] https://www.nhs.uk/conditions/statins/considerations/