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Understanding Cholesterol-Lowering Medications (cont.)


Proprotein Convertase Subtilisin Kexin Type 9 (PCSK9) Inhibitors: Examples and Use

What are some examples of PCSK9 inhibitors?

Examples of PCSK9 inhibitors approved in the U.S. include:

  • alirocumab (Praluent)
  • evolocumab (Rapatha)

How do PCSK9 inhibitors work?

Alirocumab and evolocumab are man-made injectable drugs that reduce cholesterol levels in the blood. They are members of a new class of drugs called proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors. Cholesterol is carried in the blood to a large extent by particles of LDLs that are removed from the blood by liver cells. The particles are removed from the blood by low-density lipoprotein receptors (LDLR) on liver cells. PCSK9 is a protein on liver cells that promotes the destruction of LDLR. Therefore, a decrease in LDLR levels by PCSK9 results in higher blood levels of LDL cholesterol.

Alirocumab and evolocumab are antibodies, which means that they are proteins that bind to another protein and inactivate them. Alirocumab and evolocumab bind to the PCSK9 protein and prevent it from destroying LDLR. By inhibiting PCSK9, alirocumab and evolocumab increase the number of LDLRs available to remove LDL cholesterol and consequently reduce LDL cholesterol levels in blood.

Who should not use these PCSK9 inhibitors?

People should not use PCSK9 inhibitors if they fit any of the following situations:

  • You are allergic to PCSK9 inhibitors or their ingredients.

Use: PCSK9 inhibitors are used for treatment of adults with heterozygous familial hypercholesterolemia (HeFH), homozygous familial hypercholesterolemia (HoFH), or clinical atherosclerotic cardiovascular disease (CVD) who are taking other cholesterol lowering medications but require additional lowering of cholesterol. PCSK9 inhibitors are injected under the skin every two weeks or once a month.

PCSK9 inhibitors: Interactions and Side Effects

Drug or food interactions: There are no drug interactions listed for PCSK9 inhibitors.

Side Effects: PCSK9 inhibitors are well tolerated and serious side effects are rare.

PCSK9 inhibitors should not be used in people with a history of serious hypersensitivity reactions to the product. Hypersensitivity reactions include itching, rash, hives, and serious reactions that have required hospitalization in some patients. PCSK9 inhibitors should be discontinued if signs or symptoms of serious allergic reactions occur.

The most common side effects associated with PCSK9 inhibitors include:

  • injection site reactions,
  • symptoms of the common cold, and
  • flu-like symptoms.

Other side effects include:

Liver problems have also occurred from use of PCSK9 inhibitors.

Bile Acid Sequestrants

What are some examples of bile acid sequestrants available in the U.S.?

Examples include:

How do bile acid sequestrants work?

These drugs bind with cholesterol-containing bile acids in the intestines and are then eliminated in the stool. The usual effect of bile acid sequestrants is to lower LDL cholesterol by about 10%-20%. Small doses of sequestrants can produce useful reductions in LDL cholesterol. Bile acid sequestrants are sometimes prescribed in combination with a statin to enhance cholesterol reduction. When these drugs are combined, their effects are added together to lower LDL cholesterol by more than 40%. These drugs are not effective for lowering triglycerides.

Who should not use these bile acid sequestrants?

Individuals who are allergic to bile acid sequestrants or who have a medical history of bile obstruction should not use these agents. Patients with phenylketonuria should not take aspartame-containing bile acid sequestrants such as Questran Light.

Use: Bile acid sequestrant powders must be mixed with water or fruit juice and are typically taken once or twice (rarely, three times) daily with meals. Tablets must be taken with large amounts of fluids to avoid stomach and intestinal problems.

Drug or food interactions: Bile acid sequestrants decrease the ability of the body to absorb numerous drugs such as:

They also inhibit the absorption of fat-soluble vitamins (including vitamin A and E); thus, patients taking these agents for a long time may need vitamin supplementation. Take bile acid sequestrants two hours before or after antacids, since antacids may decrease their effectiveness. Talk to your doctor or pharmacist for more information about the best time to take your medications.

Side effects: Bile acid sequestrants are not absorbed from the gastrointestinal tract, and 30 years of experience with these drugs indicates that long-term use is safe. These agents may cause constipation, bloating, nausea, or gas.

Medically Reviewed by a Doctor on 11/6/2015

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