In August, a case of liver damage following the intake of the gastroesophageal reflux disease treatment Fexuclu (active ingredient: fexuprazan) was reported in a British medical journal. However, concerns about the drug's safety are not considered high.

According to industry sources on the 27th, domestic medical professionals and experts generally agree that the case is an idiosyncratic reaction (DILI) of a single patient and is unlikely due to the drug's structural toxicity. It is described as an exceptional idiosyncratic reaction observed in a specific patient, lacking sufficient grounds to question the drug's inherent safety. Experts warn that overinterpreting a single case could unnecessarily increase anxiety. However, some suggest that even if such cases are rare, further monitoring and data collection post-prescription are necessary.

The reported case is considered academically significant as it showed changes in liver function twice in the same patient. However, the medical community views it as a typical case of 'idiosyncratic drug-induced liver injury (idiosyncratic DILI)' that occurs rarely due to individual metabolic characteristics or immune responses.

Professor Kim Yoon-jun, a leading authority in liver disease and a professor of gastroenterology at Seoul National University Hospital (President of the Korean Association for the Study of the Liver), stated, “Idiosyncratic drug-induced liver injury can be seen as an unpredictable phenomenon caused by individual metabolic constitution and immune mechanisms rather than the drug's structural toxicity,” adding, “Caution is needed when judging the overall safety of a drug based on a single case.”

There are concerns about the excessive interpretation of academic information introduced as a single case, as patients may experience unnecessary anxiety. It was noted that a single case is suitable as clinical observation showing the surveillance system is functioning but cannot serve as a basis for determining the drug's inherent risk or safety.

In fact, the Korean Association for the Study of the Liver reportedly does not recommend risk assessment based on a single case. Professor Kim Yoon-jun (President of the Korean Association for the Study of the Liver) explained, “It is a principle to comprehensively secure evidence using causal assessment tools like RUCAM, a global standard for evaluating drug-induced liver toxicity,” and stated, “In the case of Fexuclu, it is considered a clinically very stable agent, and there is no evidence to restrict its use due to hepatotoxicity.”

This case is evaluated as demonstrating that the safety management system is effectively capturing and addressing adverse reactions early. Professor Kim emphasized, “All drugs can have different reactions depending on individual genetic, immunological characteristics, and underlying liver disease conditions,” and stressed that “checking liver function before administration and promptly discontinuing and monitoring in case of adverse reactions is key to safety.”

According to Daewoong Pharmaceutical, the main ingredient of Fexuclu, fexuprazan, was designed to eliminate structural hepatotoxic elements discussed in the existing P-CAB (potassium-competitive acid blocker) class during its development. No clinically significant cases of liver damage were reported in the approval clinical trials.

Fexuclu, sold globally by Daewoong Pharmaceutical, has been prescribed to millions, but no similar patterns of liver damage have been repeatedly reported. If there were structural issues with the drug itself, similar patterns should have accumulated across various patient groups, but such circumstances have not been confirmed. Consequently, Daewoong Pharmaceutical and medical professionals consider the case to be an exceptional reaction observed only in a specific patient.

Professor Kim Yoon-jun also clarified this point. He stated, “Fexuprazan has been reported to have very low liver enzyme fluctuation rates in domestic and international clinical trials, and clinically significant liver damage cases are extremely rare in real-world data, including large-scale post-marketing patient data,” adding, “Idiosyncratic DILI varies in onset, clinical presentation, and recovery speed for each patient, but such patterns have not been repeatedly accumulated in Fexuclu.”

Popular News