Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the blood [1]. According to the sources provided, there is no clear evidence to suggest that Lipitor reduces the effectiveness of blood pressure medication.

One study found that adding Lipitor to effective blood pressure treatment provided a significant reduction in heart attacks or deaths from heart attacks over five years [2]. However, this study did not examine the interaction between Lipitor and blood pressure medication specifically.

Another study published in the Journal of Clinical Hypertension found that atorvastatin did not significantly affect blood pressure control in patients with high blood pressure [3]. The study concluded that atorvastatin can be safely used in combination with blood pressure medication.

In summary, based on the sources provided, there is no clear evidence to suggest that Lipitor reduces the effectiveness of blood pressure medication. However, it is important to consult with a healthcare provider before taking any new medications or changing existing medication regimens.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.pfizer.com/news/press-release/press-release-detail/adding_lipitor_early_to_effective_blood_pressure_treatment_provided_a_significant_reduction_in_heart_attacks_or_deaths_from_heart_attacks_over_five_years
[3] https://pubmed.ncbi.nlm.nih.gov/21881597/