Studies have consistently shown that Lipitor (atorvastatin), a widely prescribed statin, significantly reduces low-density lipoprotein (LDL) cholesterol levels within a relatively short period of time [1].

Clinical trials have demonstrated that Lipitor reduces LDL cholesterol by as much as 40-60% in patients with high cholesterol [2]. The American College of Cardiology and the American Heart Association recommend that patients start seeing significant reductions in LDL cholesterol levels after taking statins like Lipitor for four to six weeks [3].

Moreover, a study published in the Journal of Clinical Pharmacology found that patients who took Lipitor for two weeks experienced a 26% reduction in LDL cholesterol levels [4]. These results suggest that patients can expect to see significant reductions in LDL cholesterol within a few weeks of taking Lipitor.

It's essential to note that individual results may vary, and the rate at which Lipitor reduces cholesterol levels can depend on a patient's starting cholesterol levels, adherence to medication, and other factors [5]. However, in general, Lipitor has been shown to be effective in reducing LDL cholesterol levels within several weeks of treatment.

Sources:
[1] https://www.drugpatentwatch.com/drug/Atorvastatin
[2] https://www.clinicaltrials.gov (Study ID: NCT00122648)
[3] 2014 AHA/ACC Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults
[4] Journal of Clinical Pharmacology, Volume 46, Issue 7, 2006
[5] https://www.drugs.com/atorvastatin.html