R Regular, Human Insulin Injection (rDNA origin) USP is a polypeptide hormone structurally identical to natural human insulin and is produced by rDNA technology, utilizing Saccharomyces cerevisiae (bakers' yeast) as the production organism. Human insulin has the empirical formula C257H383N65O77S6 and a molecular weight of 5808 Da.
Figure 1. Structural formula of human insulin
Novolin R is a sterile, clear, aqueous, and colorless solution, that contains human insulin (rDNA origin) 100 units/mL, glycerin 16 mg/ml, metacresol 3 mg/mL and zinc chloride approximately 7 µg/mL. The pH is adjusted to 7.4. Hydrochloric acid 2N and/or sodium hydroxide 2N may be added to adjust pH.
Insulin is a polypeptide hormone that controls the storage and metabolism of carbohydrates, proteins, and fats. This activity occurs primarily in the liver, in muscle, and in adipose tissues after binding of the insulin molecules to receptor sites on cellular plasma membranes.
Insulin promotes uptake of carbohydrates, proteins, and fats in most tissues. Also, insulin influences carbohydrate, protein, and fat metabolism by stimulating protein and free fatty acid synthesis, and by inhibiting release of free fatty acid from adipose cells. Insulin increases active glucose transport through muscle and adipose cellular membranes, and promotes conversion of intracellular glucose and free fatty acid to the appropriate storage forms (glycogen and triglyceride, respectively). Although the liver does not require active glucose transport, insulin increases hepatic glucose conversion to glycogen and suppresses hepatic glucose output. Even though the actions of exogenous insulin are identical to those of endogenous insulin, the ability to negatively affect hepatic glucose output differs on a unit per unit basis because a smaller quantity of an exogenous insulin dose reaches the portal vein.
Administered insulin, including Novolin R, substitutes for inadequate endogenous insulin secretion and partially corrects the disordered metabolism and inappropriate hyperglycemia of diabetes mellitus, which are caused by either a deficiency or a reduction in the biologic effectiveness of insulin. When administered in appropriate doses at prescribed intervals to patients with diabetes mellitus, Novolin R temporarily restores their ability to metabolize carbohydrates, proteins and fats.
Novolin R is a sterile, aqueous, and colorless solution of human insulin with a short duration of action. The pharmacologic effect of Novolin R begins approximately one-half (½) hour after subcutaneous administration. The effect is maximal between 2½ and 5 hours and terminates after approximately 8 hours. The onset of action of intravenous insulin is more rapid.