Lipitor is a prescription drug used to lower cholesterol levels in the blood. According to the FDA, it is classified as a Pregnancy Category X drug, which means that it is contraindicated during pregnancy due to the potential risk of fetal harm. However, there is limited information available on whether Lipitor is safe to use during breastfeeding.

The drug is known to pass into breast milk, and there have been reports of adverse effects in infants whose mothers were taking Lipitor while breastfeeding. According to a study published in the National Library of Medicine, the concentration of Lipitor in breast milk was found to be 0.006-0.03% of the maternal dose, which is considered to be low. However, the study also notes that Lipitor has a long half-life, which means that it can accumulate in the infant's system over time.

Based on the available information, it is recommended that women who are breastfeeding should not take Lipitor unless it is absolutely necessary. If Lipitor is deemed necessary, then the mother should be closely monitored for any adverse effects on the infant, such as changes in feeding or sleeping patterns, and the infant's lipid levels should be monitored as well.

In conclusion, Lipitor is classified as a Pregnancy Category X drug and is not recommended for use during breastfeeding unless it is absolutely necessary. Women who are considering taking Lipitor while breastfeeding should consult with their healthcare provider to weigh the potential benefits and risks.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.fda.gov/media/150774/download
[3] https://www.ncbi.nlm.nih.gov/books/NBK501361/