Protropin (somatrem for injection) is a polypeptide hormone produced by recombinant DNA technology. Protropin (somatrem) has 192 amino acid residues and a molecular weight of about 22,000 daltons. The product contains the identical sequence of 191 amino acids constituting pituitary-derived human growth hormone plus an additional amino acid, methionine, on the N-terminus of the molecule. Protropin is synthesized in a special laboratory strain of E. coli bacteria which has been modified by the addition of the gene for human growth hormone production.
Protropin is a highly purified preparation. Biological potency is determined by measuring the increase in body weight induced in hypophysectomized rats.
Protropin is a sterile, white, lyophilized powder intended for intramuscular or subcutaneous administration after reconstitution with Bacteriostatic Water for Injection, USP (benzyl alcohol preserved).
Each 5 mg Protropin vial contains 5 mg (approximately 15 IU) somatrem, lyophilized with 40 mg mannitol, and 1.7 mg sodium phosphates (0.1 mg sodium phosphate monobasic and 1.6 mg sodium phosphate dibasic).
Each 10 mg Protropin vial contains 10 mg (approximately 30 IU) somatrem, lyophilized with 80 mg mannitol, and 3.4 mg sodium phosphates (0.2 mg sodium phosphate monobasic and 3.2 mg sodium phosphate dibasic).
Phosphoric acid may be used for pH adjustment.
Bacteriostatic Water for Injection, USP is a sterile water containing 0.9 percent benzyl alcohol per mL as an antimicrobial preservative packaged in a multi-dose vial. The diluent pH is 4.5-7.0.