Amoxicillin, an analog of ampicillin, is a semisynthetic antibiotic that inhibits the biosynthesis of cell wall mucopeptide. It has a broad-spectrum bactericidal activity against most strains of aerobic gram-positive and gram-negative microorganisms .
Pharmacokinetics Details in DRUGDEX® Back to top
Oral: time to peak concentration, 1 h to 2 h 
Protein binding: approximately 20% 
Renal: approximately 60% (mostly unchanged) 
Dialyzable: yes (hemodialysis) 
Elimination Half Life
61.3 min 
This data is from micromedex.
The last number (half-life) will tell you about how long the drug will be available in a non-compromised adult. So after about an hour, 500mg will be left, 2 hours 250mg left, 3 hours 125mg left, and so on. Usually about 4 half-lives will bring the drug down to levels that are non-therapeutic and therefore not significant.