Praluent (alirocumab) lowers LDL cholesterol by blocking a protein called PCSK9, which normally destroys the receptors your liver uses to pull cholesterol out of your bloodstream. By keeping more of those receptors active, Praluent helps your liver clear significantly more LDL cholesterol, with clinical trials showing reductions of roughly 50% or more from baseline levels.
The Role of PCSK9 in Cholesterol
To understand how Praluent works, it helps to know what PCSK9 does in the first place. Your liver cells are covered with LDL receptors, tiny docking stations that grab LDL cholesterol particles from the blood and pull them inside the cell for disposal. Normally, after an LDL receptor does its job, it gets recycled back to the cell surface to grab another cholesterol particle. This recycling loop is what keeps your cholesterol levels in check.
PCSK9 disrupts that loop. It’s a protein made by liver cells and released into the bloodstream, where it latches onto LDL receptors on the liver’s surface. Once PCSK9 is attached, the receptor can no longer go through its normal recycling process. Instead of returning to the cell surface, the receptor gets dragged into the cell’s waste-processing compartment (the lysosome) and destroyed. Fewer receptors on the surface means less cholesterol gets cleared from the blood, and LDL levels rise.
Recent research from the American Heart Association has clarified the precise mechanism: when an LDL receptor enters a cell inside an acidic compartment, it normally changes shape in a way that signals a sorting protein called SNX17 to send it back to the surface. PCSK9 prevents that shape change, so the sorting signal never fires and the receptor is degraded instead. The result is a steady loss of LDL receptors and, over time, higher circulating cholesterol.
How Praluent Blocks PCSK9
Praluent is a fully human monoclonal antibody, meaning it’s an immune protein engineered to bind tightly to one specific target: free-floating PCSK9 in the bloodstream. By grabbing onto PCSK9 before it can reach LDL receptors, Praluent essentially neutralizes it. The receptors are left alone, cycle back to the liver surface as intended, and continue pulling LDL cholesterol out of circulation.
The net effect is a higher density of active LDL receptors on each liver cell. More receptors mean faster clearance of LDL particles from the blood. This is the same basic pathway that statins use (statins cause liver cells to produce more LDL receptors), which is why Praluent and statins can work together: statins increase receptor production while Praluent prevents receptor destruction.
How Much It Lowers Cholesterol
In the ODYSSEY clinical trial program, patients taking Praluent 150 mg every four weeks saw their LDL cholesterol drop by about 52% from baseline at 24 weeks, compared to a slight increase of roughly 5% in the placebo group. The difference between the two groups was statistically significant, with a 56 percentage point gap. Patients in those trials started with average LDL levels around 155 to 164 mg/dL.
These reductions are substantially larger than what most oral cholesterol medications achieve alone, which is why Praluent is typically added on top of existing therapy rather than used as a first-line treatment.
Cardiovascular Benefits Beyond Cholesterol Numbers
Lowering LDL cholesterol is useful only if it translates into fewer heart attacks and strokes. The ODYSSEY OUTCOMES trial tested that directly in patients who had recently experienced a serious cardiac event. Patients who achieved LDL levels below 50 mg/dL on Praluent had a 26% lower rate of major cardiovascular events (heart attack, stroke, cardiac death, or hospitalization for unstable angina) compared to placebo, with a hazard ratio of 0.74. Patients who ended up with LDL levels above 50 mg/dL, often due to poorer adherence, saw a smaller and statistically uncertain benefit.
This dose-response pattern reinforces the principle that the lower you drive LDL in high-risk patients, the greater the protection.
Who Praluent Is Approved For
The FDA has approved Praluent for several overlapping groups:
- Adults at increased cardiovascular risk who need to reduce the chance of heart attack, stroke, cardiac death, or hospitalization for unstable angina.
- Adults with high cholesterol who need additional LDL lowering beyond diet and exercise.
- Adults and children aged 8 and older with heterozygous familial hypercholesterolemia (HeFH), an inherited condition that causes very high cholesterol from a young age.
- Adults with homozygous familial hypercholesterolemia (HoFH), a rarer and more severe inherited form.
Current guidelines from the American College of Cardiology and American Heart Association (2026) position PCSK9 inhibitors like Praluent as an add-on for patients already on the highest tolerated statin dose who still haven’t reached their cholesterol targets. For very high-risk patients with existing heart disease, guidelines recommend adding Praluent or a similar drug to reach an LDL goal below 55 mg/dL. For patients with severe hypercholesterolemia (LDL at or above 190 mg/dL), the recommendation is even stronger, carrying the highest level of clinical endorsement. Praluent is also specifically recommended for patients with elevated Lp(a), a genetically determined heart disease risk factor, who haven’t met their cholesterol goals on statins alone.
How You Take It
Praluent is a self-administered injection, not a pill. The standard starting dose is 75 mg injected under the skin every two weeks. If that doesn’t lower your LDL enough, the dose can be increased to 150 mg every two weeks. For people who prefer fewer injections, an alternative schedule of 300 mg once monthly is available, given as two consecutive 150 mg injections at different sites.
You inject it into the thigh, abdomen, or upper arm using a pre-filled pen or syringe, rotating sites each time. The pen needs to warm at room temperature for 30 to 40 minutes before use, since it’s stored in the refrigerator. You should not inject into areas with sunburn, rashes, or active skin irritation.
Storage and Handling
Praluent belongs in the refrigerator between 36°F and 46°F, kept in its original carton to protect it from light. If you need to travel or don’t have fridge access, it can stay at room temperature (up to 77°F) for a maximum of 30 days, after which any unused pens must be discarded. It should never be frozen, shaken, or exposed to extreme heat.
Common Side Effects
Most people tolerate Praluent well. The most frequently reported side effects are injection site reactions: pain, redness, or irritation where the needle goes in. Some people experience flu-like symptoms including fever, chills, muscle pain, cough, headache, and fatigue. Diarrhea and muscle spasms have also been reported. These side effects generally don’t require medical attention and tend to be mild.