Amoxicillin-Clavulanic Acid: Higher Risk Of Hepatotoxicity Than With Amoxicillin Alone

WESTPORT, Jul 01 (Reuters)
Development of hepatitis and jaundice associated with use of amoxicillin and clavulanic acid was first reported in 1988, and now researchers have confirmed that patients receiving this combination therapy are at a higher risk for acute liver injury than patients who take amoxicillin alone.

Dr. Luis A. Garcia Rodriguez of Madrid, Spain, with colleagues from the Netherlands and the United States, conducted a retrospective review of data on more than 93,000 users of the combination therapy and on more than 360,000 users of amoxicillin alone.

In the June 24 issue of Archives of Internal Medicine, Dr. Garcia Rodriguez and his colleagues report that they found 14 cases of acute liver injury among users of the single agent, with half of these cases classified as hepatocellular injuries, and 21 cases of acute liver injury among users of the combination drug, with three quarters classified as cholestatic. The incidence rates of acute liver injury associated with the combination drug and with amoxicillin alone were 1.7 and 0.3 per 10,000 prescriptions, respectively. None of the cases were fatal.

Among users of amoxicillin and clavulanic acid, say the authors, the risk of developing acute liver injury was more than three times greater after a course of two or more consecutive prescriptions than after a single course of therapy. The risk was also increased in elderly users of the combination agent. "The combination of advancing age and repeated prescriptions resulted in a risk of developing acute liver injury greater than one per one thousand users of amoxicillin and clavulanic acid together," Dr. Garcia Rodriguez said.

The authors conclude that the cholestatic injuries were most likely related to an idiosyncratic reaction to the clavulanic acid.

Arch Intern Med 1996;156:1327-1332.

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