There is no direct scientific evidence to suggest that Lipitor, a medication used to treat high cholesterol, negatively affects flexibility in yoga practice. Lipitor, also known as atorvastatin, works by blocking a substance your body needs to make cholesterol [1].

Yoga's effects on the body are largely physical, increasing flexibility and muscle tone, improving balance and respiration, and reducing stress [2]. The potential side effects of Lipitor, as listed by the FDA, include headache, stomach pain, constipation, diarrhea, gas, heartburn, nausea, muscle or joint pain, and changes in some laboratory tests [1]. None of these side effects directly impact the body's flexibility.

However, it's important to note that individual experiences can vary, and some people may personally find that certain medications, including Lipitor, affect their physical abilities, including their flexibility in yoga practice. If you have concerns about how a medication might be affecting your yoga practice, it's always a good idea to consult with your healthcare provider [3].

Sources:
[1] <https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/lipitor-atorvastatin-calcium-answers-consumers>
[2] <https://www.yogaalliance.org/Portals/0/2016%20Yoga%20in%20America%20Study%20Results.pdf>
[3] <https://www.drugpatentwatch.com/drugs/lipitor>