The U.S. Food and Drug Administration announced Tuesday it was giving drug makers only two years, instead of three, to make sure bar codes are on drugs dispensed in hospitals. The final bar-coding regulation was set to be published in today’s Federal Register and take effect 60 days thereafter.

After reviewing just under 200 comments on the rule, which was first proposed last March, the FDA said it made four significant changes. Perhaps most noteworthy is the shortened compliance time frame for drug makers, as well as an exemption for drug samples. Seniors consume more drugs than any other age cohort.

Most prescription and over-the-counter drugs used in hospitals, as well as blood and blood byproducts, will be required to have linear bar codes on them under the new regulation. Using the bar codes would prevent an average of 25,000 medical errors per year over a 20-year period, officials estimate.