somapacitan（LYS/CYS)

Somapacitan (LYS/CYS) is a recombinant long-acting growth hormone analogue designed for once-weekly treatment of growth hormone deficiency (GHD) in adults and children. It is a modified human growth hormone (rhGH) with chemical conjugation—most likely polyethylene glycol (PEG)—at specific lysine (LYS) and cysteine (CYS) residues to prolong its half-life and sustain biological activity. This modification impacts pharmacokinetics, enabling less frequent dosing while preserving the native growth-promoting functions such as stimulating growth, metabolism, and acting via the growth hormone receptor (GHR).

Appearance:

• White to off-white lyophilized powder; upon reconstitution, forms a clear, colorless solution.

Source:

•  Produced by recombinant DNA technology in systems like E. coli or mammalian cells, purified for pharmaceutical formulation.

Molecular Weight:

• Higher than native rhGH (~22 kDa) due to PEG or similar modifications; exact weight depends on conjugate size.

Structure:

• Human growth hormone amino acid sequence chemically modified at defined lysine and cysteine residues with PEG or another moiety; modification site critical for long-acting profile.

Biological Activity:

• Activates GHR signaling pathways

• Promotes bone growth, lean mass increase, fat metabolism

• Modified sites enhance half-life, reducing injection frequency

Purity and Microbial Contamination:

• Purity: ≥98% by HPLC, SDS-PAGE

• Must meet sterility, bioburden, and endotoxin limits (LAL assay)

Identity and Quality Control:

• Mass spectrometry confirms molecular weight and modification

• Amino acid analysis and peptide mapping verify sequence and modification site

• HPLC and SDS-PAGE assess purity and aggregation

• Bioactivity assays confirm growth-promoting function

• Immunochemical assays evaluate receptor binding

Shelf Life and Storage

Applications:

• Treatment of growth hormone deficiency in adults and children

• Research into sustained release GH analogues and receptor interactions

Key Characteristics:

• Recombinant human GH derivative

• PEG or chemically modified at specific LYS/CYS residues to prolong half-life

• Maintains biologic function while enabling once-weekly dosing

• Pharmaceutical-grade lyophilized formulation

Research and Information Sources:

• Regulatory approvals: FDA, EMA websites for official documents

• Clinical trials: PubMed, clinicaltrials.gov for efficacy and safety data

• PEGylation of proteins: Literature on PEGylated GH and other biotherapeutics

• Patents: Google Patents and USPTO for manufacturing and structural details

• Keywords for literature search: “Somapacitan mechanism of action,” “PEGylated growth hormone,” “Somapacitan clinical trials,” “growth hormone receptor binding affinity,” “recombinant human growth hormone manufacturing”