Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood. According to the prescribing information, liver enzyme tests should be performed before starting Lipitor and as clinically indicated thereafter. The recommended frequency of liver testing varies depending on the patient's individual risk factors and medical history [3].

The National Center for Biotechnology Information (NCBI) states that liver function tests should be performed before starting Lipitor and then periodically thereafter, especially during the first year of treatment. The frequency of liver function tests should be based on the patient's individual risk factors, including the presence of liver disease, alcohol consumption, and other medications the patient may be taking [2].

Medscape recommends liver function tests before starting Lipitor and then periodically thereafter. For patients with normal liver function, liver function tests should be performed every six months during the first year of treatment, and then as clinically indicated thereafter. For patients with pre-existing liver disease or increased risk factors, liver function tests should be performed more frequently [1].

In conclusion, the recommended frequency of liver testing for patients taking Lipitor varies depending on individual risk factors and medical history. It is recommended to perform liver function tests before starting Lipitor and periodically thereafter, especially during the first year of treatment. The frequency of testing should be based on the patient's individual risk factors, including the presence of liver disease, alcohol consumption, and other medications the patient may be taking. It is important to follow the recommendations of a healthcare provider regarding the frequency of liver function tests while taking Lipitor.

Sources:
[1] Medscape - Lipitor (atorvastatin) dosing, indications, interactions, adverse effects, and more. https://reference.medscape.com/drug/lipitor-atorvaliq-atorvastatin-342446
[2] NCBI - Statins: Atorvastatin (Lipitor). https://www.ncbi.nlm.nih.gov/books/NBK548236/
[3] Drug Patent Watch - Lipitor. https://www.drugpatentwatch.com/p/tradename/LIPITOR