Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the blood [1]. According to drugs.com, there is a potential interaction between atorvastatin and Tums (calcium carbonate), a medication used to relieve heartburn and indigestion. Tums can decrease the absorption of atorvastatin, which may reduce its effectiveness [2]. Therefore, it is recommended to take atorvastatin at least two hours before or after taking Tums [2][3]. It is important to consult with a healthcare provider before taking any new medication or supplement to avoid potential drug interactions and side effects [3].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.drugs.com/drug-interactions/atorvastatin-with-tums-regular-strength-276-0-464-3778.html
[3] https://www.verywellhealth.com/statin-side-effects-and-drug-interactions-698202