Somatropin [somatropin (rDNA origin) for injection] is a human growth hormone (hGH) produced by recombinant DNA technology. Somatropin has 191 amino acid residues and a molecular weight of 22,125 daltons. The amino acid sequence of the product is identical to that of pituitary-derived hGH. Somatropin may contain not more than fifteen percent deamidated GH at expiration. The deamidated form of GH has been extensively characterized and has been shown to be safe and fully active.
Somatropin is a sterile, white lyophilized powder intended for subcutaneous administration after reconstitution with Bacteriostatic Water for Injection, USP (benzyl alcohol preserved).

Each 3.33 mg Somatropin vial contains 3.33 mg (approximately 10 IU) somatropin, lyophilized with 90 mg mannitol, 3.4 mg sodium phosphates (0.8 mg sodium phosphate monobasic and 2.6 mg sodium phosphate dibasic), and 3.4 mg glycine.
Bacteriostatic Water for Injection, USP is sterile water containing 0.9 percent benzyl alcohol per mL as an antimicrobial preservative packaged in a multidose vial. The diluent pH is 4.5 – 7.0