Clavulanic acid

Clavulanic acid
Formula C8H9NO5
Molar Mass (g·mol−1) 199,1608
Physical State solid
Melting Point (°C) 117,7-118
Boiling Point (°C) 545,8
PKS Value 2,7
CAS Number 58001-44-8
PUB Number 5280980
Drugbank ID DB00766
Solubility soluble in water


Clavulanic acid is an active substance used in combination with the antibiotic amoxicillin or with cephalosporins to compensate for antibiotic resistance in bacteria. By itself, the drug has only a weak antibacterial effect.



Bacteria produce beta-lactamase enzymes which are capable of deactivating the activity of antibiotics. Due to the structural similarity of these enzymes, clavulanic acid can bind to them, protecting the antibiotic from inactivation. At the same time, this also broadens the spectrum of activity of the antibiotic.


The beta-lactamase inhibitor is well absorbed into the gastrointestinal tract after oral administration, with a bioavailability of 64%. During the first six hours after ingestion, approximately half of clavulanic acid is excreted unchanged in the urine. Intermediates after metabolism are excreted in the urine and feces and in exhaled air. The half-life, similar to amoxicillin, is 45-90 minutes.


Side effects

Adverse side effects include nausea, vomiting, diarrhea, and skin rashes. Tolerability improves with concomitant food intake. More severe side effects may include liver damage, anemia, and renal inflammation.

Toxicological data

In case of overdose, changes in fluid and electrolyte balance and gastrointestinal symptoms may occur.
Bei Nagetieren wurde eine geringe orale Toxizität mit einer LD50 von mehr als 2000 mg/kg festgestellt, bei Ratten traten gastrointestinale Störungen und Mortalität schon bei Dosen von 125 mg/kg auf.

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Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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