PCSK9 Inhibitors Explained: Evolocumab vs Inclisiran for High Cholesterol (Singapore Doctor Guide)

PCSK9 inhibitors represent a relatively new class of cholesterol-lowering medications that have changed how doctors approach difficult-to-treat high cholesterol.

In Singapore, two PCSK9-targeted therapies are available — evolocumab and inclisiran — both prescribed for individuals whose LDL cholesterol remains high despite maximally tolerated statin therapy, or who cannot tolerate statins.

This guide explains what PCSK9 inhibitors are, how the two options compare, and what patients should understand before discussing them with their doctor.

What Is PCSK9?

PCSK9 stands for proprotein convertase subtilisin/kexin type 9, a protein produced primarily by the liver.

Its role in cholesterol metabolism is significant:

• PCSK9 binds to LDL receptors on liver cells

• This binding causes the receptors to be broken down

• Fewer receptors mean less LDL cholesterol is removed from the bloodstream

• Blood LDL levels rise as a result

In simple terms, PCSK9 acts like a regulator that limits how much "bad cholesterol" the liver can clear.

When PCSK9 is blocked or reduced, more LDL receptors remain active, and more cholesterol is removed from circulation.

What Are PCSK9 Inhibitors?

PCSK9 inhibitors are medications designed to reduce PCSK9 activity, allowing the liver to clear more LDL cholesterol from the blood.

They are typically used when:

• LDL cholesterol remains elevated despite maximally tolerated statin therapy

• Patients cannot tolerate statins due to side effects

• Familial hypercholesterolaemia is present

• Established cardiovascular disease requires aggressive LDL reduction

Evolocumab vs Inclisiran: How Are They Different?

Both medications target PCSK9, but they work through fundamentally different mechanisms.

Evolocumab

Evolocumab is a monoclonal antibody — a lab-engineered protein that binds directly to PCSK9 in the bloodstream and neutralises it.

• Binds and inactivates circulating PCSK9

• Allows more LDL receptors to function

• Effects last roughly 2–4 weeks per dose

Inclisiran

Inclisiran uses a newer mechanism called small interfering RNA (siRNA) — a technology that silences the genetic instructions for producing PCSK9 in the first place.

• Blocks the production of PCSK9 inside liver cells

• Fewer PCSK9 molecules are made

• Effects last several months per dose

Side-by-Side Comparison

Important Considerations

These are general comparisons.

The right choice depends on individual cardiovascular risk, lifestyle, ability to self-administer injections, and clinical guidelines.

A doctor will weigh all factors before recommending one over the other.

How Are They Administered?

Both medications are given as subcutaneous injections (under the skin, similar to insulin injections).

Evolocumab

• Injected every 2 weeks (140 mg) or monthly (420 mg)

• Patients can be trained to self-inject at home

• Uses a pre-filled pen or auto-injector device

Inclisiran

• Administered by a healthcare professional

• Schedule: initial dose, second dose at 3 months, then every 6 months

• Typically given in a clinic setting

How Effective Are PCSK9 Inhibitors?

Both medications produce substantial LDL reductions when added to statin therapy.

Typical results in clinical trials:

• LDL reduction of approximately 50–60% beyond what statins achieve alone

• Reductions are sustained with continued treatment

• Some patients achieve LDL levels below current optimal targets

What This Means in Practice

For a patient on a statin with LDL of 3.5 mmol/L, adding a PCSK9 inhibitor may bring LDL closer to 1.5–1.8 mmol/L.

For high-risk patients — those with established cardiovascular disease or familial hypercholesterolaemia — this level of reduction may meaningfully lower future cardiovascular event risk.

Who Might Be Considered for PCSK9 Inhibitors?

PCSK9 inhibitors are typically considered for individuals who:

• Have established cardiovascular disease (prior heart attack, stroke, or known coronary disease) and persistently elevated LDL despite maximal statin therapy

• Have familial hypercholesterolaemia — a genetic condition causing very high LDL from a young age

• Are statin-intolerant due to muscle pain, liver effects, or other documented side effects

• Are at very high cardiovascular risk and require aggressive LDL reduction

What Are the Side Effects?

PCSK9 inhibitors are generally well tolerated.

Common side effects (both medications):

• Injection site reactions (redness, mild pain, bruising)

• Muscle aches

• Mild upper respiratory symptoms

Less common:

• Allergic reactions

• Headache

• Fatigue

Long-term safety data continues to accumulate, particularly for inclisiran, which is the newer of the two.

What Patients Should Discuss With Their Doctor

Before starting a PCSK9 inhibitor, important areas to discuss include:

• Your overall cardiovascular risk and LDL targets

• Whether statins or other oral therapies have been optimised first

• Your comfort with injections — frequency and self-administration

• Cost considerations and insurance coverage

• Monitoring requirements, including blood tests

• Long-term commitment — these medications are typically continued indefinitely

Cost Considerations in Singapore

PCSK9 inhibitors are significantly more expensive than statins.

Costs vary depending on:

• Specific medication and dosing schedule

• Hospital, polyclinic, or private clinic setting

• MediShield Life and integrated shield plan coverage

• Whether the medication is on the Standard Drug List or Medication Assistance Fund

A doctor or pharmacist can provide specific cost estimates based on your situation.

PCSK9 Inhibitors vs Other Cholesterol Treatments

PCSK9 inhibitors sit alongside other cholesterol-lowering options.

How Treatments Are Combined

In high-risk patients, doctors may layer treatments — for example, statin + ezetimibe + PCSK9 inhibitor — to achieve aggressive LDL targets.

The goal is always to match treatment intensity to the patient's individual cardiovascular risk.

How Long Does Treatment Continue?

PCSK9 inhibitors are typically considered long-term therapy.

LDL levels return to pre-treatment values within weeks to months of stopping, so consistent treatment is important to maintain benefits.

Doctors review treatment regularly to assess effectiveness, side effects, and changes in cardiovascular risk.

Frequently Asked Questions (Singapore-Focused)

1. Are PCSK9 inhibitors a replacement for statins?

No. They are typically added to statin therapy, not used in place of it, unless statins cannot be tolerated.

2. How quickly do PCSK9 inhibitors lower LDL?

LDL reductions are typically seen within 2–4 weeks of starting treatment.

3. Are evolocumab and inclisiran available in Singapore?

Yes, both are prescribed in Singapore by qualified doctors.

4. Can I take PCSK9 inhibitors if I have side effects from statins?

This is one of the recognised situations where PCSK9 inhibitors may be considered. Discuss with your doctor.

5. Do I need blood tests during treatment?

Yes. Lipid panels and other blood tests are used to monitor response and overall cardiovascular health.

6. Can I stop PCSK9 inhibitors once my LDL is controlled?

Generally no. LDL levels rise again after stopping, so treatment is usually continued long-term.

7. Are these injections painful?

Most patients describe injections as mildly uncomfortable but tolerable. Injection-site reactions are usually minor.

8. Can I self-inject evolocumab at home?

Yes, after appropriate training. Inclisiran is typically given in a clinic.

9. Are PCSK9 inhibitors covered by insurance?

Coverage varies by insurer and policy. Check directly with your provider.

10. Can young people use PCSK9 inhibitors?

In specific situations such as familial hypercholesterolaemia, yes — but always under specialist guidance.

11. What if I miss a dose?

Contact your clinic for advice. Do not double-dose without medical guidance.

12. Can I drink alcohol while on PCSK9 inhibitors?

Moderate alcohol use is generally not contraindicated, but discuss with your doctor.

13. Do PCSK9 inhibitors interact with other medications?

Interactions are limited compared with many other drugs, but always inform your doctor of all medications you take.

14. Are there pregnancy considerations?

PCSK9 inhibitors are not recommended in pregnancy. Discuss family planning with your doctor before starting.

15. Will my GP prescribe PCSK9 inhibitors?

Some GPs prescribe these medications, though many cases are co-managed with cardiologists or lipidologists.

Final Thoughts

PCSK9 inhibitors represent a meaningful advance in the management of difficult-to-treat high cholesterol.

Both evolocumab and inclisiran are effective options — the right choice depends on individual cardiovascular risk, lifestyle preferences, and clinical context.

A combination of:

• Established lifestyle and dietary habits

• First-line cholesterol therapies where appropriate

• Specialist input when needed

can support long-term cardiovascular health in a personalised way.

For more info on PCSK9 inhibitors see https://www.repatha.com/ or https://www.leqvio.com/

Disclaimer: The information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. The content is not intended to be a comprehensive source of information and should not be relied upon as such. Reliance on any information provided in this article is solely at your own risk. The authors and the publisher do not endorse or recommend any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned in the article. Any reliance on the information in this article is solely at the reader's own risk.