Amoxicillin: in vitro and pharmacological studies.

Amoxicillin is a new semisynthetic penicillin which is active in vitro against gram-positive cocci (except penicillin G-resistant Staphylococcus aureus) and most isolates of Proteus mirabilis and Escherichia coli. Its in vitro activity is quite similar to ampicillin, but it produces higher serum levels after oral administration. The mean peak serum levels of amoxicillin in 11 normal volunteers were 2.30 mug/ml after 125 mg, 3.43 mug/ml after 250 mg, 6.75 mug/ml after 500 mg, and 9.90 mug/ml after 1 g. About 70% of the drug was excreted in the urine during the first 6 hr.