Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood. The appropriate dosage of Lipitor depends on various factors such as age, gender, and medical history. According to the American Academy of Family Physicians (AAFP) [2], the initial dose of Lipitor is 10-20 mg once daily, which can be increased up to 80 mg once daily if necessary. However, the dosage may need to be adjusted in certain situations.

According to Medscape [3], dosage adjustment should be considered when Lipitor is used in combination with certain medications such as cyclosporine, fibrates, and niacin. This is because these medications can increase the risk of developing muscle-related side effects such as myopathy and rhabdomyolysis. In such cases, the dose of Lipitor should be reduced to avoid these side effects.

Additionally, dosage adjustment should be considered in patients with liver disease or renal impairment. According to Drug Patent Watch [1], patients with liver disease should start with a lower dose of Lipitor and should be closely monitored for liver function. Similarly, patients with severe renal impairment should start with a lower dose of Lipitor and should be closely monitored for adverse effects.

In conclusion, the appropriate dosage of Lipitor depends on various factors and should be determined by a healthcare professional. Dosage adjustment should be considered in certain situations such as when Lipitor is used in combination with certain medications or in patients with liver disease or renal impairment. Close monitoring is necessary to ensure the safety and effectiveness of Lipitor therapy.

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