It is short acting human insulin preparation that can be given intravenously if necessary to cover emergencies. It is also refered as soluble insulin or neutral insulin or unmodified insulin. It’s onset of action is 30-60 minutes; while duration of action is 4-12 hours. Peak of action occurs in 2-4 hours. It is synthesized in a special non-disease-producing laboratory strain of Escherichia coli bacteria that has been genetically altered to produce human insulin. The time course of action of any insulin may vary considerably in different individuals or at different times in the same individual. As with all insulin preparations, the duration of action of regular insulin is dependent on dose, site of injection, blood supply, temperature, and physical activity.