Amoxicillin–Clavulanic Acid Oral Versus Intravenous Bioavailability
Oral administration of amoxicillin–clavulanic acid results in lower systemic exposure than intravenous administration for both components, with oral bioavailability that is substantially higher for amoxicillin than for clavulanic acid. [1][2]
Component-Specific Bioavailability
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Amoxicillin: Oral absolute bioavailability is 88.7% relative to intravenous administration (range 70.9% to 105.5%) in a pharmacokinetic study of normal subjects. [1]
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Clavulanic acid: Oral bioavailability is 60.0% ± 23.1% in healthy men receiving an oral dose of clavulanic acid in combination with amoxicillin, showing marked variability in absorption. [2]
Practical Interpretation of the Difference
- The relative oral-to-IV exposure difference is therefore approximately 10–25% lower for amoxicillin (88.7% oral vs 100% IV). [1]
- The relative oral-to-IV exposure difference is therefore approximately 40% lower on average for clavulanic acid (60% oral vs 100% IV). [2]
Variability Considerations
- Clavulanic acid oral exposure shows wide variability across individuals (reported range reflected by the mean ± SD data). [2]
- Amoxicillin oral bioavailability shows interindividual variability (reported range 70.9% to 105.5%). [1]