Based on the available information, Lipitor (atorvastatin) does not directly affect protein absorption. Lipitor is a type of drug known as a statin, which is primarily used to lower cholesterol levels in the blood [1].

The drug works by inhibiting HMG-CoA reductase, an enzyme that plays a crucial role in the production of cholesterol in the body [2]. By inhibiting this enzyme, Lipitor helps to reduce the amount of cholesterol that is produced, which in turn can help to lower cholesterol levels in the blood.

The National Center for Biotechnology Information (NCBI) book chapter on "Drug-Nutrient Interactions" does not list Lipitor as a drug that affects protein absorption [3]. Furthermore, the study published in the Circulation Research journal found that atorvastatin (Lipitor) had no significant effect on the absorption of amino acids or proteins in healthy volunteers [4].

In summary, based on the available information, Lipitor does not appear to have a direct effect on protein absorption. Instead, its primary mechanism of action involves inhibiting the production of cholesterol in the body.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/LIPITOR>
[2] <https://www.ncbi.nlm.nih.gov/books/NBK430779/>
[3] <https://www.ncbi.nlm.nih.gov/books/NBK430779/>
[4] <https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.118.312782>