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Nonlinearity of amoxicillin absorption kinetics in human
G Paintaud1, G Alván, M L Dahl
1Department of Clinical Pharmacology, Karolinska Institute, Huddinge University Hospital, Sweden.
European Journal of Clinical Pharmacology
|January 1, 1992
Summary
Amoxicillin absorption in the gastrointestinal tract is variable and dose-dependent. This study reveals non-linear absorption kinetics, suggesting factors beyond simple diffusion influence how the body processes amoxicillin.
Area of Science:
- Pharmacokinetics
- Gastrointestinal Physiology
Background:
- Specialized gastrointestinal absorption of amoxicillin is suggested in humans and demonstrated in animals.
- Understanding amoxicillin absorption kinetics is crucial for optimizing therapeutic efficacy.
Purpose of the Study:
- To investigate the rate and extent of amoxicillin absorption in healthy subjects.
- To analyze the absorption kinetics following different oral doses and compare them to intravenous administration.
Main Methods:
- Six healthy subjects received 500 mg IV and two oral doses (500 mg and 3 g suspension).
- Absorption kinetics were analyzed using compartmental modeling, noncompartmental methods, and deconvolution to calculate absorption rates.
- Dose-dependency was assessed by comparing plasma concentrations and fraction of dose absorbed.
Main Results:
- Dose-dependency in amoxicillin absorption was observed, with lower than expected plasma concentrations and fraction absorbed at the 3 g dose.
- Zero-order absorption kinetics were apparent in some subjects after the 500 mg dose.
- No consistent pattern of pure first-order or zero-order absorption was observed across all individuals and doses.
Conclusions:
- Gastrointestinal absorption of amoxicillin exhibits variable and non-linear characteristics.
- The absorption process is influenced by multiple factors, extending beyond simple diffusion.
- These findings highlight the complexity of amoxicillin oral bioavailability.