How does inhibiting HMG‑CoA reductase lower LDL?
Lipitor (atorvastatin) inhibits HMG‑CoA reductase, the liver enzyme that controls the rate of cholesterol synthesis. When the liver makes less cholesterol, it compensates by increasing the number of LDL receptors on hepatocytes. Those additional receptors pull more LDL (“bad cholesterol”) from the bloodstream into the liver, which lowers circulating LDL levels.
Why does lower cholesterol synthesis translate into lower blood LDL?
LDL particles deliver cholesterol to tissues. If the liver reduces its internal cholesterol production, it runs low on cholesterol and shifts toward importing it from blood via LDL receptors. That increased uptake reduces the amount of LDL remaining in circulation, lowering LDL concentrations.
What happens to other lipids (like triglycerides and HDL)?
While HMG‑CoA reductase inhibition most directly reduces LDL, it also tends to improve other lipid measures. Statins commonly lower triglycerides and raise HDL modestly, but the largest and most consistent effect is typically LDL reduction. (The LDL receptor upregulation is the main mechanistic driver.)
How quickly do LDL levels change after starting a statin?
LDL reductions occur fairly soon after starting therapy because LDL receptor activity changes with decreased cholesterol synthesis in the liver. The full effect is typically reached after continued dosing over several weeks as receptor-mediated clearance stabilizes.
What determines how much LDL drops?
LDL response varies by dose and individual factors such as baseline cholesterol level, statin dose intensity, and adherence. Stronger inhibition (higher-potency/higher dose) generally leads to larger LDL reductions, consistent with greater suppression of cholesterol synthesis and greater LDL receptor upregulation.