Based on the information provided, I cannot find any evidence that Lipitor, a medication used to treat high cholesterol, directly increases or decreases the efficacy of other drugs. Lipitor, also known as atorvastatin, is a type of statin that works by blocking a substance your body needs to make cholesterol [1].

However, Lipitor can interact with other medications, which may affect how well they work or increase the risk of side effects. For instance, Lipitor can interact with certain antibiotics and antifungal medications, increasing the risk of muscle damage [1]. This does not mean that Lipitor decreases the efficacy of these drugs; rather, it suggests that combining these medications can have harmful side effects.

It is crucial to consult with a healthcare provider or pharmacist before starting or stopping any medication or supplement, especially if you are taking other medications. They can provide personalized advice based on your medical history and current medications [1].

In summary, based on the available information, Lipitor does not appear to have a direct impact on the efficacy of other drugs. However, it can interact with certain medications, which may affect their safety or efficacy.

Sources:
[1] DrugPatentWatch.com. (n.d.). Atorvastatin (Lipitor). Retrieved from https://www.drugpatentwatch.com/drugs/atorvastatin