How Do PCSK9 Inhibitors Work?

Reviewed on 3/31/2021

How do PCSK9 Inhibitors work?

PCSK9 (proprotein convertase subtilisin kexin type 9) inhibitors are a new class of cholesterol-lowering drugs that work by lowering low-density lipoprotein (LDL) or “bad” cholesterol in the blood. Doctors usually prescribe statins for high cholesterol. Although in most people statins work great, some people cannot take them due to their side effects. PCSK9 inhibitors have shown great effectiveness in lowering high cholesterol as well as be used in patients who do not tolerate statins and have been therefore considered a game-changer.

Excess cholesterol in our body is primarily swept away by receptors on our liver cells, but a protein called “PCSK9” blocks this action by destroying the receptors on the liver cells causing the cholesterol levels to go up. PCSK9 inhibitors (man-made monoclonal antibody or RNA-based) get attached to this protein and block their action. As a result, more receptors can continue to do their job and this lowers the amount of LDL cholesterol in the blood.

PCSK9 inhibitors can be taken on their own or in addition to a statin and are more expensive than other cholesterol drugs.

Although statins are taken orally, PCSK9 inhibitors are given as a shot in your upper arm/stomach/upper thigh every two or four weeks. The injection is usually easy with little pain.

Right now, there are only two FDA-approved PCSK9 inhibitors: Praluent (alirocumab) and Repatha (evolocumab).

Uses of PCSK9 inhibitors

Statins are the most prescribed drug for lowering cholesterol. However, they do not work for everyone. Your doctor may suggest you take PCSK9 inhibitors if:

  • You have genetic high cholesterol (familial hypercholesterolemia): For the majority of the people with this condition, LDL cholesterol cannot be brought down to a healthy level even with the highest dose of statins.
  • You’re at risk for heart attack/stroke: If you already have heart disease and other medications, like statins, haven’t lowered your cholesterol enough.
  • You can’t take statins: If you are not able to take statins due to side effects, like muscle pain, cramps, or weakness. Statins can also cause liver damage, confusion, memory loss, or an increase in blood sugar level.


What is cholesterol? See Answer

Side effects of PCSK9 inhibitors

Common side effects include:

The side effects are generally mild and often go away after a few weeks.

Other rare side effects include:

  • Allergic reactions (if you suffer severe rash or swollen face, get immediate help from your doctor)
  • Trouble breathing

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

PCSK9 inhibitors drugs

  • alirocumab
  • evolocumab
  • inclisiran 
  • Praluent
  • Repatha

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