After reviewing the provided sources, there is no clear evidence that suggests Lipitor can decrease antihistamine potency. Lipitor is a medication used to lower cholesterol levels and is not known to interact with antihistamines.

The first source [1] provides information on the drug Lipitor, including its active ingredient, dosage, and patent information. However, it does not mention any interactions with antihistamines.

The second source [2] is a study that investigated the effects of atorvastatin, the active ingredient in Lipitor, on the immune system. The study found that atorvastatin had immunomodulatory effects, but it did not mention any interactions with antihistamines.

The third source [3] is an article from the American Academy of Family Physicians that discusses the use of antihistamines for the treatment of allergies. The article provides information on the different types of antihistamines and their side effects, but it does not mention any interactions with Lipitor.

In conclusion, based on the provided sources, there is no evidence to suggest that Lipitor can decrease antihistamine potency. However, it is always important to consult with a healthcare professional before taking any new medications, especially if you are already taking other medications or have underlying health conditions.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://pubmed.ncbi.nlm.nih.gov/22947909/
[3] https://www.aafp.org/pubs/afp/issues/2007/0801/p391.html