Food and Drug Regulations

C.04.582 The insulin preparation “NPH Insulin” or “Isophane Insulin” shall be a sterile preparation of rod-shaped crystals containing insulin, protamine and zinc, suspended in a buffered aqueous medium, shall have a pH of not less than 7.0 and not more than 7.8 and shall contain

• (a) weight by volume, not less than 0.15 per cent and not more than 0.25 per cent anhydrous disodium phosphate, and either

  • (i) not less than 1.4 per cent and not more than 1.8 per cent glycerin and not less than 0.15 per cent and not more than 0.17 per cent metacresol and not less than 0.06 and not more than 0.07 per cent phenol, or

  • (ii) not less than 0.40 per cent and not more than 0.45 per cent sodium chloride and not less than 0.7 per cent and not more than 0.9 per cent glycerin and not less than 0.18 per cent and not more than 0.22 per cent metacresol; and

• (b) as determined by an acceptable method, for each 1,000 International Units of insulin,

  • (i) not more than 8.5 milligrams of nitrogen,

  • (ii) not less than 3.0 milligrams and not more than 6.0 milligrams of protamine except that the ratio of the protamine to the insulin shall be not less than the isophane ratio and shall not exceed the isophane ratio by more than 10 per cent,

  • (iii) not less than 0.16 milligram and not more than 0.40 milligram of zinc, and

  • (iv) no protease activity significant for the stability of NPH insulin.