Eloralintide: Molecular Structure

Molecular Structure#

Eloralintide (LY3841136) is a synthetic, long-acting amylin analog designed through rational peptide engineering to achieve two key objectives: selective activation of the AMY1 amylin receptor subtype and extended pharmacokinetic half-life suitable for once-weekly dosing.

The molecule is derived from human amylin (islet amyloid polypeptide, IAPP), a 37-amino acid peptide hormone co-secreted with insulin from pancreatic beta cells. Native amylin has poor pharmaceutical properties -- it readily aggregates into amyloid fibrils, has a short half-life (approximately 15 minutes), and activates amylin and calcitonin receptors non-selectively.

Design Principles#

Eloralintide's molecular design addresses each of these limitations:

1. Receptor selectivity: Three non-coded amino acid substitutions (ornithine at position 11, alpha-methyl-phenylalanine at position 15, N-methyl-asparagine at position 22) confer 12-fold selectivity for AMY1R over calcitonin receptor and 11-fold selectivity over AMY3R
2. Extended half-life: A C20 fatty diacid is conjugated via dual gamma-glutamic acid linkers to lysine at position 26, promoting reversible albumin binding that extends circulation time for once-weekly dosing
3. Structural stability: A disulfide bridge between Cys2 and Cys7 stabilizes the bioactive conformation and reduces aggregation propensity
4. N-terminal modification: A gamma-glutamic acid cap at the N-terminus may contribute to metabolic stability

Chemical Properties#

Receptor Selectivity#

The key molecular innovation of eloralintide is its selectivity profile. Amylin receptors are heterodimeric complexes of the calcitonin receptor (CTR) with receptor activity-modifying proteins (RAMPs):

This selectivity is clinically relevant because calcitonin receptor activation is associated with nausea, and non-selective amylin analogs such as cagrilintide activate CTR at similar potencies to amylin receptors. Eloralintide's reduced CTR engagement may explain its improved GI tolerability observed in both preclinical and clinical studies.

Pharmacokinetics#

Eloralintide exhibits pharmacokinetic properties engineered for once-weekly subcutaneous administration:

• Absorption: Subcutaneous injection with slow, sustained absorption from the depot site
• Distribution: Reversible albumin binding via the C20 fatty diacid prolongs circulation
• Half-life: Extended, supporting weekly dosing (exact value not publicly disclosed)
• Dose proportionality: Dose-proportional pharmacokinetics confirmed in Phase 1 studies across the evaluated dose range
• Steady state: Achieved during chronic once-weekly dosing

Pharmacodynamics#

• Dose-dependent reduction in food intake and body weight
• Preferential fat mass loss with reduced lean mass depletion in preclinical studies
• Onset of weight loss observed within the first weeks of treatment
• Effects are reversible upon treatment discontinuation

Comparison with Other Amylin Analogs#

Related Reading#

• Eloralintide overview and research guide
• Peptides similar to eloralintide
• Eloralintide research evidence