Ampicillin is in a class of medications called penicillin. It is chemically described as (2S,5R,6R)-6-((R)-2-amino-2-phenylacetamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0] heptane-2-carboxylic acid. Its molecular formula is C16H19N3O4S and its molecular weight is 349.40 g/mol.
Ampicillin was discovered in 1958 and came into commercial use in 1961.The World Health Organization classifies ampicillin as critically important for human medicine.
Ampicillin is used to treat infections by many gram-positive and gram-negative bacteria. It was the first "broad spectrum" penicillin with activity against gram-positive bacteria, including Streptococcus pneumoniae, Streptococcus pyogenes. Activity against gram-negative bacteria includes Neisseria meningitidis, Haemophilus influenzae.
Ampicillin is used to treat certain infections that are caused by bacteria such as meningitis (infection of the membranes that surround the brain and spinal cord); and infections of the throat, sinuses, lungs, reproductive organs, urinary tract, and gastrointestinal tract.
The dosage forms available for ampicillin include oral capsules or liquid suspensions. There is also a powder that can be made into an injection form. Capsule- 250 / 500mg, Oral suspension- 125/ 250mg, Powder: 125mg, 250mg, 500mg.
MECHANSIM OF ACTION:
Ampicillin is a beta-lactam antibiotic and is classified as aminopenicillins.
The mode of action of beta-lactam antimicrobials on sensitive organisms can be considered a two-step process:
1) In the first step, the drug binds to primary receptors called membrane-bound penicillin-binding proteins (PBPs). These proteins perform vital roles in cell cycle-related; formation of cell wall peptidoglycan structure. Therefore, the inactivation of PBPs by bound antimicrobials immediately affects their function.
2) The second stage comprises the physiological effects caused by this receptor-ligand interaction. PBPs are involved in the cell wall's late stages of peptidoglycan synthesis. Because peptidoglycan maintains the integrity of the cell wall, which resides in a hypotonic environment, its disruption causes lysis and cell death.
It is important to recognize that ampicillin is primarily bactericidal against susceptible bacteria due to its inhibition of cell wall synthesis.
Penicillinase (a Beta-lactamase) cleaves the beta-lactam ring and results in resistance to ampicillin. Hence ampicillin is usually combined with ?-lactamase inhibitors like sulbactam.
Ampicillin is often used to treat urinary infections with Gram-negative enteric bacterial etiologies. The drug is also used to treat respiratory tract infections. Additionally ampicillin is uniformly effective against group B Streptococcus, but is ineffective against Enterobacter, Hemophilus influenzae, Pseudomonas and indole positive Proteus infections
Some of the impurities of Ampicillin are-
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