Repackaged LDL particles called HDL particles are then released into the blood stream. These particles are sensed by the liver through the HDL-receptors. Thus the liver gets constant information as to how much LDL and HDL are present in the blood. Decreased cholesterol biosynthesis steps up the levels of the LDL-receptor resulting in the positive cycle for lowered cholesterol levels in serum. For patients who have familial hypercholesterolemia due to defective LDL-receptor genes these drugs are not effective.
Statins are most effective cholesterol lowering drugs.
Statins lower total cholesterol and LDL particles. These are competitive inhibitors. The HMG-CoA has a conformation similar to the lactone moiety of statins resulting in binding at the same site without any productive effect. A 15-30 point drop in LDL could be reasonably expected with most statins after a therapy of about 1 month. Although possible, statins typically do not affect the concentrations of steroid hormones in circulation.