Which of the following medications is a PCSK9 inhibitor?

Alirocumab (Praluent) is classified as a PCSK9 inhibitor, which means it is specifically designed to target and inhibit the protein convertase subtillisin/kexin type 9 (PCSK9). This protein plays a significant role in regulating cholesterol levels in the body by promoting the degradation of LDL receptors, which are responsible for removing low-density lipoprotein (LDL) cholesterol from the bloodstream. By inhibiting PCSK9, alirocumab increases the number of LDL receptors available, leading to a reduction in LDL cholesterol levels, which is beneficial for patients at risk of cardiovascular diseases.

The other medications listed in the question serve different purposes. Gemfibrozil (Lopid) is a fibrate that primarily works to lower triglyceride levels and can raise HDL cholesterol, but it does not affect PCSK9. Zetia (ezetimibe) works by reducing the absorption of cholesterol in the intestines, and while it can lower LDL cholesterol, it does so through a different mechanism. Niacin (B3) is used to increase HDL cholesterol and lower triglycerides, but it does not interact with PCSK9 or offer the same LDL-lowering effects as a PCSK9 inhibitor. Thus,