Aspoxicillin is an injectable, amino acid-type penicillin highly active against Gram-positive ad Gram-negative bacteria, including the beta-lactamase producing Bacillus fragilis. It is reportedly effective in the treatment of peritonitis, pneumonia and bronchitis. Adverse reactions are: rash, urticaria, skin itching, vomiting, abdominal pain.

Faropenem is a unique antimicrobial penem being developed for oral administration. It markets it in two forms: faropenem sodium and faropenem medoxomil. The high binding affinities of faropenem to penicillin-binding proteins from gram-negative and gram-positive bacteria are mirrored by its pronounced and concentration-dependent bactericidal effect. It is usually used to treat a wide range of infections such as skin, respiratory and otorhinologic infections. The most commonly reported adverse reactions include diarrhea, abdominal pain, loose stool, rash and nausea. The FDA refused to approve faropenem – the applicant have to conduct new studies and clinical trials to prove the drug treats community-acquired pneumonia, bacterial sinusitis, chronic bronchitis, and skin infections.

Cefmatilen (codenamed S-1090) is an orally-active cephalosporin antibiotic, that shows high activity against a variety of Gram-positive and Gram-negative bacteria, including Streptococcus pyogenes and Neisseria gonorrhoeae.

Ritipenem (FCE 22101), a penem antibiotic, penicillin binding protein inhibitor, is potent against both gram-positive and -negative bacteria, and its acetoxymethyl ester (FCE 22891; ritipenem-acoxil) is orally available. Ritipenem is manufactured by Tanabe Seiyaku in the ritipenem acoxil prodrug form, which can be taken orally. It is not FDA approved in the United States.

Lenampicillin is a prodrug of ampicillin that inhibits bacterial penicillin binding proteins (transpeptidase) and thus is effective against a wide range of bacterial infections. The drug was developed and marketed in Japan (Takacillin, Varacillin), however its current marketing status is unknown and supposed to be discontinued.

Ritipenem (FCE 22101), a penem antibiotic, penicillin binding protein inhibitor, is potent against both gram-positive and -negative bacteria, and its acetoxymethyl ester (FCE 22891; ritipenem-acoxil) is orally available. Ritipenem is manufactured by Tanabe Seiyaku in the ritipenem acoxil prodrug form, which can be taken orally. It is not FDA approved in the United States.

Cefetamet pivoxil is an oral third-generation cephalosporin which is hydrolysed to form the active agent, cefetamet. Cefetamet has excellent in vitro activity against the major respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and group A beta-haemolytic streptococci; it is active against beta-lactamase-producing strains of H. influenzae and M. catarrhalis, but has poor activity against penicillin-resistant S. pneumoniae. Cefetamet has marked activity against Neisseria gonorrhoeae and possesses a broad spectrum of activity against Enterobacteriaceae. Both staphylococci and Pseudomonas spp. are resistant to cefetamet. Cefetamet pivoxil has been investigated in the treatment of both upper and lower community-acquired respiratory tract infections and has demonstrated equivalent efficacy to a number of more established agents, namely cefaclor, amoxicillin and cefixime. In complicated urinary tract infections, cefetamet pivoxil showed similar efficacy to cefadroxil, cefaclor and cefuroxime axetil. Cefetamet pivoxil was effective in the treatment of otitis media, pneumonia, pharyngotonsillitis and urinary tract infections in children. Cefetamet is not extensively bound to plasma proteins. Cefetamet has a relatively small apparent volume of distribution consistent with that of other beta-lactam antibiotics. The absorption and disposition of cefetamet in human subpopulations [i.e. children, elderly (< 75 years of age), renal impairment, liver disease and patients taking concomitant drugs] have been studied extensively. Only impaired renal function appears to significantly alter the elimination of this drug. Cefetamet pivoxil exerts its bactericidal action by inhibition the final transpeptidation step of peptidoglycan synthesis in the bacterial cell wall by binding to one or more of the Penicillin-binding Proteins (PBPs).

Faropenem is a unique antimicrobial penem being developed for oral administration. It markets it in two forms: faropenem sodium and faropenem medoxomil. The high binding affinities of faropenem to penicillin-binding proteins from gram-negative and gram-positive bacteria are mirrored by its pronounced and concentration-dependent bactericidal effect. It is usually used to treat a wide range of infections such as skin, respiratory and otorhinologic infections. The most commonly reported adverse reactions include diarrhea, abdominal pain, loose stool, rash and nausea. The FDA refused to approve faropenem – the applicant have to conduct new studies and clinical trials to prove the drug treats community-acquired pneumonia, bacterial sinusitis, chronic bronchitis, and skin infections.

Cefozopran hydrochloride is a third-generation cephalosporin that was launched for the treatment of severe infections in immunocompromised patients caused by staphylococci and enterococci. While it shows a very broad antibacterial spectrum against Gram-positive and Gram-negative organisms, it is particularly potent against S. aureus, Enterococcus faecalis, P. aeruginosa, and Citrobacter freundii. It is resistant to hydrolysis by most chromosomal and plasmid mediated β-lactamases and is reported to be active against respiratory, urinary tract, obstetrical, gynecological, soft tissue, and surgical infections. Similar to β-lactams, cephalosporins interfere with PBP (penicillin binding protein) activity involved in the final phase of peptidoglycan synthesis. PBP’s are enzymes which catalyze a pentaglycine crosslink between alanine and lysine residues providing additional strength to the cell wall. Without a pentaglycine crosslink, the integrity of the cell wall is severely compromised and ultimately leads to cell lysis and death. Resistance to cephalosporins is commonly due to cells containing plasmid encoded β-lactamases.