IPLEX^®
(mecasermin rinfabate [rDNA origin] injection)

IPLEX^® (mecasermin rinfabate [rDNA origin] injection) is an aqueous solution for injection containing a binary protein complex of human insulin-like growth factor-1 (rhIGF-1) and human insulin-like growth factor-binding protein-3 (rhIGFBP-3), both produced by recombinant DNA technology.

rhIGF-1 and rhIGFBP-3 are produced by two separate E. coli strains: one containing the human gene for insulin-like growth factor-1 (IGF-1), the other containing the human gene for insulin-like growth factor-binding protein-3 (IGFBP-3). IGF-1 consists of 70 amino acids in a single chain with three intramolecular disulfide bridges and a molecular weight of 7649 daltons. The amino acid sequence of the rhIGF-1 protein is identical to that of endogenous human IGF-1. IGFBP-3 consists of 264 amino acid residues with a molecular weight of 28,732 daltons. The amino acid sequence of the rhIGFBP-3 protein is identical to that of endogenous human IGFBP-3. Endogenous IGFBP-3 contains 18 cysteine residues that are all paired in disulfide bonds to form the biologically active molecule, but the pairings have not been fully elucidated. The rhIGF-1 and rhIGFBP-3 proteins are complexed in a 1:1 molar ratio for formation of mecasermin rinfabate with a molecular weight of 36,381 daltons. IGFBP-3 from human plasma is glycosylated, whereas rhIGFBP-3 produced in E. coli is non-glycosylated. Glycosylated and non-glycosylated IGFBP-3 bind IGF-1 with similar affinities.

Primary structures for rhIGF-1/rhIGFBP-3:

Recombinant human insulin growth factor binding protein-3 (rhIGFBP-3)

Disulfide bonds not fully elucidated

IPLEX^® is prepared to a final concentration of 36 mg/0.6 mL in 50 mM sodium acetate and 105 mM sodium chloride with a final pH of 5.5. IPLEX^® is for subcutaneous injection only and is a preservative-free, sterile, clear, colorless-to-slightly-yellow liquid.

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