Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the blood [1]. There is no evidence to suggest that Lipitor reduces the potency of pain medication. However, it is important to note that the expiration date of medication can affect its potency [2]. According to a study published in the Journal of Pharmaceutical Sciences, some medications can lose potency over time, especially if they are not stored properly [3]. Therefore, it is important to follow the expiration date on the medication label and store medications in a cool, dry place to ensure their potency. In summary, Lipitor does not reduce the potency of pain medication, but it is important to pay attention to the expiration date and storage conditions of all medications to ensure their effectiveness.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.health.harvard.edu/staying-healthy/drug-expiration-dates-do-they-mean-anything
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463373/