Drug makers will not need regulatory approval for every change in their manufacturing processes under new guidelines designed to prevent supply disruptions, U.S. health officials said on Wednesday.

Companies can skip the prior approval requirement if they have developed adequate tests and procedures to show certain changes will not affect product safety or effectiveness, the Food and Drug Administration said in a report.

The modification is part of a just-completed, two-year effort to overhaul regulation of pharmaceutical manufacturing, a major issue for drug makers.

In the past, Schering-Plough Corp., Eli Lilly and Co. and other companies had trouble meeting federal production standards and faced delays in the approval of new medicines.

Some critics said the changes amounted to decreased regulation that could harm patients if problems were not uncovered before medicines were released to the public.

“I don’t think it’s a good idea. From a patient perspective, it is questionable and intermittently dangerous,” said Dr. Sidney Wolfe, head of Public Citizen’s Health Research Group, a consumer group.

Health and Human Services Secretary Tommy Thompson, in a statement, said the FDA’s plan would ensure “consistently high quality” for the U.S. drug supply.

The FDA said the new measures would help drugs get on the market quicker and prevent supply shortages or disruptions. The agency also wants to encourage companies to adopt new technologies.

“In the past, as a result of the many uncertainties in drug manufacturing, the FDA exercised extensive control over virtually every aspect of the manufacturing process,” the FDA report said.

“Consequently, pharmaceutical companies have often been reluctant to change their manufacturing processes and equipment because of perceived, and sometimes real, regulatory hurdles.”

The new system will focus inspections on plants that produce medicines with the most potential to harm patients if quality control lapses occur. Companies with effective quality control systems in place will be subject to fewer and less extensive inspections, the FDA said.