There are two mainstream industrial production routes for the bulk drug of inj glucagon 1 mg: Fmoc solid-phase peptide chemical synthesis and recombinant biosynthesis in yeast. The finished product is a 1 mg lyophilized powder injection per vial.

Chemical synthesis serves as the primary route for generic drugs: Wang resin is adopted as the solid support, and a fragment condensation strategy is applied to sequentially couple 29 Fmoc-protected amino acids from the C-terminus to the N-terminus. Pseudoproline protection is utilized for racemization-prone residues such as aspartic acid and glutamine to suppress side reactions of peptide chain aggregation and improve crude peptide purity.

After full-sequence coupling, trifluoroacetic acid cleavage is performed to simultaneously remove side-chain protecting groups. Filtration and concentration yield crude peptide. Preparative reversed-phase HPLC with gradient elution is used for purification to eliminate deletion fragments, oxidized methionine and hydrolytic impurities.

The main peak fraction is desalted and lyophilized to obtain high-purity glucagon bulk drug with purity exceeding 98.5%, and mass spectrometry verifies that the molecular weight matches the reference standard.

The original brand adopts yeast recombinant expression technology: the human GCG gene is transfected into yeast strains to express proglucagon, and site-specific cleavage by protease PC2 releases the mature 29-amino-acid peptide. Chromatography is carried out to separate bacterial proteins followed by fine purification.

In the formulation stage, the purified bulk drug is aseptically blended with lactose excipients and quantitatively filled into vials with an accurate loading of 1 mg active peptide per vial, then vacuum-lyophilized into sterile powder. The matching solvent is sterile water for injection for reconstitution prior to subcutaneous or intravenous administration.

Products from both routes feature identical primary structures and equivalent in vivo blood glucose-elevating activity. Comprehensive quality control covering impurity profiling, microbial testing and endotoxin detection is mandatory to meet pharmacopoeial standards for injectable grade materials.

Following insulin purification in 1921, researchers observed that crude pancreatic extracts induced transient hyperglycemia prior to hypoglycemia after injection. In 1923, Kimball and Murlin verified that this hyperglycemic substance was an independent hormone and named it glucagon, establishing its physiological function as an insulin antagonist.

In 1948, scientists confirmed that the hormone is synthesized by pancreatic islet α-cells. The first crystalline purification was achieved in 1953, verifying its polypeptide nature. Amino acid sequencing was completed between 1950 and 1960, identifying glucagon as a linear peptide consisting of 29 amino acids. In 1960, glucagon for injection obtained FDA approval for emergency treatment of severe hypoglycemia.

Subsequent molecular biological analysis of the GCG gene clarified the maturation mechanism of proglucagon via proteolytic cleavage. The industrialization of solid-phase peptide synthesis and yeast recombinant technology enabled large-scale manufacturing of 1 mg emergency injection kits, establishing glucagon as a standard clinical emergency medication.