Are the adverse drug reactions of amoxycillin and amoxycillin-clavulanic acid similar?

Abstract

In an attempt to assess the relative toxicity of amoxycillin and amoxycillin-clavulanic acid, we compared the adverse drug reactions reports collected using the spontaneous reporting system of a Regional Drug Surveillance Centre of Spain for both drugs between November 1986 and December 1992. During the 7-year period 1986-92, the 247 reports of amoxycillin-clavulanic acid represent twice the number of reports of amoxycillin alone, and the number of reports related with sales received concerning the association were higher than those concerning amoxycillin alone. The adverse effects classified as severe were quantitatively and qualitatively similar for both drugs and gastrointestinal and skin are the most common system-organ affected by both drugs. With amoxycillin-clavulanic acid there is a higher proportion of stomatological reactions reported and a later onset of adverse drug reactions related with oropharyngeal lesions, and the reaction of the resistance mechanism when compared with the other organs and systems affected. The duration of the adverse drug reactions to amoxycillin-clavulanic acid is longer than for amoxycillin alone. (i) the adverse drug reactions profile of both drugs is different; (ii) the higher reporting rate for amoxycillin-clavulanic acid may be due to more recent marketing; and (iii) amoxycillin-clavulanic acid produces proportionately more gastrointestinal and fewer skin adverse reactions than amoxycillin alone.