Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood and reduce the risk of heart disease and stroke [2]. According to the Mayo Clinic, Lipitor is usually taken once a day, with or without food, at any time of the day [3]. It is important to take the medication at the same time every day to maintain a consistent level of the drug in the body.

The dosage of Lipitor can vary depending on the individual's cholesterol levels and medical history. The initial recommended dose is usually 10 or 20 mg once daily, and the maximum recommended dose is 80 mg once daily [2]. However, the dose may be adjusted by a healthcare provider based on the individual's response to the medication and any side effects experienced [3].

There is no specific frequency for changing the schedule of taking Lipitor mentioned in the sources provided. It is important to follow the healthcare provider's instructions regarding the dosage and schedule of the medication. If a dose is missed, it should be taken as soon as possible, unless it is close to the time for the next dose. In that case, the missed dose should be skipped and the regular dosing schedule should be resumed [3].

In summary, Lipitor is usually taken once a day at any time of the day, with or without food. The dosage and schedule of the medication may vary depending on the individual's cholesterol levels and medical history, and should be determined by a healthcare provider. If a dose is missed, it should be taken as soon as possible, unless it is close to the time for the next dose.

Sources:
[1] Drug Patent Watch. Lipitor. Retrieved from https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] Medscape. Atorvastatin (Rx). Retrieved from https://reference.medscape.com/drug/lipitor-atorvaliq-atorvastatin-342446
[3] Mayo Clinic. Atorvastatin (Oral Route): Proper Use. Retrieved from https://www.mayoclinic.org/drugs-supplements/atorvastatin-oral-route/proper-use/drg-20067003