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CARDIOVASCULARNON-PEPTIDEPhase IIIPCSK9 INHIBITORORALMACROCYCLIC PEPTIDE

Enlicitide Decanoate

Also known as: MK-0616 · Enlicitide

17 views/week 0 citations 0 edits Updated 9/22/2026

Enlicitide decanoate is Merck's investigational oral PCSK9 inhibitor — a macrocyclic peptide engineered to deliver antibody-like target engagement in a daily pill. In the Phase 3 CORALreef programme it cut LDL cholesterol by 55.8% in hypercholesterolaemia and 59.4% in heterozygous familial hypercholesterolaemia. If approved it would be the first oral PCSK9 inhibitor.

STRUCTURE

Molecular Composition

FORMULA
C₉₂H₁₂₉FN₁₄O₁₇
MOL. WEIGHT
1,722.12 Da
CAS NUMBER
2861205-06-1
TARGET
PCSK9
ROUTE
Oral, once daily
STATUS
Phase 3 (CORALreef)
AMINO ACID CHAIN VISUALIZATION
M
Macrocyclic ring
constrained scaffold resisting gut proteases
NH-CO
P
PCSK9 interface
blocks PCSK9–LDL receptor binding
NH-CO
F
Fluorinated arene
binding affinity and metabolic stability
NH-CO
D
Decanoate moiety
salt form enabling oral formulation
NH-CO
H
Hydrophobic face
membrane permeability for gut absorption
SEQUENCEM-P-F-D-H
MECHANISMS

How It Works

🛡️
PCSK9 Blockade
PCSK9 binds the hepatic LDL receptor and tags it for destruction, so the liver clears less LDL. Enlicitide binds PCSK9 and blocks that interaction, keeping more LDL receptors on the cell surface.
💊
Oral Delivery via Macrocyclisation
A linear peptide this size would be digested before absorption. Cyclisation confers protease resistance and enough membrane permeability to survive the gut — the core innovation that makes an oral PCSK9 binder possible.
🎯
Antibody-Like Specificity Without Injection
Existing PCSK9 inhibitors are monoclonal antibodies requiring subcutaneous injection every two to four weeks. Enlicitide targets the same protein–protein interface with comparable specificity in a daily tablet.
📉
LDL Reduction Rivalling Injectables
Phase 3 reductions of 55.8–59.4% place it in the range of injectable PCSK9 antibodies, which is what makes the oral route clinically interesting rather than merely convenient.
OVERVIEW

Research Overview

Every PCSK9 inhibitor on the market is an injectable monoclonal antibody. Enlicitide is the attempt to reach the same validated target orally, using a macrocyclic peptide — a constrained ring structure that resists gut proteolysis well enough to survive oral administration while retaining antibody-like binding specificity.

Across the Phase 3 CORALreef trials it met its primary and key secondary endpoints, with adverse events comparable to placebo and low discontinuation. A cardiovascular outcomes trial (CORALreef Outcomes) is running — the study that determines whether the LDL reduction translates into fewer cardiac events. Not yet approved.

Mechanism of Action

// PCSK9 BLOCKADE

PCSK9 binds the hepatic LDL receptor and marks it for degradation, so less LDL is cleared from the blood. Enlicitide binds PCSK9 and blocks that interaction, leaving more LDL receptors on the hepatocyte surface and increasing clearance of circulating LDL cholesterol.

// MACROCYCLIC ORAL DELIVERY

The macrocyclic scaffold is the differentiator: cyclisation confers the protease resistance and membrane permeability that a conventional linear peptide of this size would lack, which is what makes oral dosing of a PCSK9 binder feasible at all.

DOSAGE

Dosage & Administration

ORAL — PHASE 3 CORALREEF PROGRAMME
DOSE
Once-daily oral tablet (approved dose not yet set)
FREQUENCY
Once daily
NOTES
CORALreef Lipids reported a 55.8% LDL-C reduction versus placebo; CORALreef HeFH reported 59.4% at week 24. Adverse events were comparable to placebo with low discontinuation. No approved dose exists yet.

Investigational. Its significance is delivery rather than target: PCSK9 inhibition is already validated by injectable antibodies, and enlicitide is the attempt to achieve it in a daily pill. The cardiovascular outcomes trial is the one that determines whether LDL lowering translates to fewer cardiac events.

CYCLING

Cycle Duration Guide

ON CYCLE
Continuous daily use (chronic lipid management, like a statin)
OFF CYCLE
Not applicable — LDL returns to baseline on discontinuation

Lipid-lowering therapy is a long-term intervention, not a cycled one. Stopping reverses the effect.

Investigational — not approved. Do not substitute for prescribed lipid therapy.

NOTES

Research Notes

Investigational, Phase 3 (CORALreef programme); cardiovascular outcomes trial ongoing. As a macrocyclic peptide it has no conventional linear sequence. Molecular weight derived from the published formula (1722.12), matching the published value.

Quick Reference
FORMULAC₉₂H₁₂₉FN₁₄O₁₇
MOL. WEIGHT1,722.12 Da
LENGTH0 amino acids
ORIGINSynthetic macrocyclic peptide (Merck)
HALF-LIFESupports once-daily oral dosing
SOLUBILITYNot publicly disclosed
CAS NO.2861205-06-1
STATUSPhase III
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TAGS
PCSK9 inhibitororalmacrocyclic peptideLDL cholesterolhyperlipidemiaMerck