Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood. The dosage of Lipitor is adjusted based on individual patient factors such as age, weight, and medical history. According to the American Academy of Family Physicians [3], the starting dose for Lipitor is usually 10-20 mg per day, which can be increased after 4 weeks to achieve the desired cholesterol level. The maximum daily dose of Lipitor is 80 mg.

Drugpatentwatch [1] provides information on the patent expiration date for Lipitor, which was November 30, 2011. This means that generic versions of Lipitor are now available, which may affect the cost and availability of the medication.

Medscape [2] provides information on Lipitor's mechanism of action, potential side effects, and drug interactions. It is important to note that dosage adjustments may be necessary for patients with liver or kidney disease, as well as those taking other medications that may interact with Lipitor.

In summary, the dosage of Lipitor is typically adjusted after 4 weeks of treatment based on individual patient factors and the desired cholesterol level. The maximum daily dose of Lipitor is 80 mg. Patients with liver or kidney disease or those taking other medications may require dosage adjustments. The patent for Lipitor expired in 2011, making generic versions of the medication available.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://reference.medscape.com/drug/lipitor-atorvaliq-atorvastatin-342446
[3] https://www.aafp.org/pubs/afp/issues/2007/0515/p1487.html