The Ministry of Food and Drug Safety will limit the use of Janus kinase (JAK) inhibitor, a treatment for inflammatory diseases, on older adults and other high-risk groups only when existing treatments prove ineffective.

“For patients 65 and older, high-risk cardiovascular groups and those with malignant tumor risks, the ministry will push for changing precautions to restrict the use of JAK inhibitors only when existing treatments do not show sufficient effects,” the ministry said.

JAK inhibitor treats various inflammatory diseases, such as rheumatoid arthritis, by blocking the action of JAK, an enzyme that regulates immunity and inflammation. The ministry has approved 65 products as JAK inhibitors based on five ingredients -- tofacitinib, baricitinib, upadacitinib, abrocitinib, and filgotinib.

The recent decision follows a safety review conducted after the ministry distributed a drug safety letter in September.

The ministry also conducted a Central Pharmaceutical Affairs Council review by combining the results of post-marketing investigations of tofacitinib and baricitinib ingredient formulations in the U.S. and Europe, opinions from experts, and measures taken by foreign regulatory agencies.

The U.S. government limits the use of all JAK inhibitors to patients without alternatives, and Europe has limited the use of tofacitinib on high-risk groups while reviewing other JAK inhibitors.

The Korean regulator also reviewed the results of recent adverse effects.

“We will continue to promptly inform drug safety information for the safe use of drugs and take safety measures thoroughly,” the ministry said.