Ampicillin

Chemical structure: β-lactam

Ampicillin has been used to study antibiotic resistance and penetration limitations, the synergy between multiple antibiotics, certain bloodstream infections, and has been used to develop PCR assays to detect resistance genes in cerebrospinal fluid.

β-lactams are inactivated by β-lactamases and for this reason ampicillin is used with a β-lactamase inhibitor.

Mode of Action: Ampicillin is a semisynthetic penicillin and a β-lactam antibiotic that inhibits bacterial cell-wall synthesis by inactivating transpeptidases on the inner surface of the bacterial cell membrane.

Mode of Resistance: Administration with β-lactamase cleaves the β-lactam ring of Ampicillin and inactivates it.

Antimicrobial Spectrum: Effective against both Gram-positive (similar to benzylpenicillin) and Gram-negative bacteria (similar to tetracyclines and chloramphenicol.

Ampicillin is reported as slightly soluble in water, practically insoluble in alcohol, chloroform, ether and fixed oils but soluble in dilute acids or bases. The solution should not be autoclaved; a stock solution should be sterilized through filtration and stored frozen, where it will be stable for months.

Store under argon. Keep container tightly closed in a dry and well-ventilated place, hygroscopic.

This product has been reported stable as supplied at 25°C at 43% and 81% relative humidity for six weeks. Additional studies have shown that the stability of Ampicillin in solution is a function of pH, temperature and the identity of the buffer. It′s activity is quickly lost when stored above pH 7. Optimal storage conditions are suggested as 2-8°C, and pH 3.8-5 where its activity was retained at 90%+ for a week.