FIBRACILLIN is a semisynthetic antibacterial agent.

Fomidacillin (also known as BRL 36650) is a type of penicillin with antibacterial activity. Studies on volunteers have shown that the drug possessed the bactericidal activity and could be a candidate for the treatment of gram-negative bacillary infections. However, information about the further development of this drug is not available.

Furbucillin is a synthetic antibacterial agent that has never been marketed. Information about the current use of this drug is not available.

Prazocillin is 6-aminopenicillanic acid derivative patented by Chinoin Gyogyszer es Vegyeszeti Termekek Gyara Rt. as a bactericidal compound. The activity of Prazocillin against Staphylococcus aureus strains was the same as that of dikloxacillin, but Prazocillin was more active against Bacillus subtilis ATCC 6633. Prazocillin had a bactericidal effect on a penicillin-resistant S. aureus strain at concentrations of 1 μg/ml. Pyrazocillin inhibits bacterial penicillinase in vitro.

Thiphencillin is a penicillin analog patented by Abbott Laboratories as an antibacterial agent. Thiphencillin shows potent antibacterial activity against various species and genera of pathogenic bacteria.

Benzylpenilloic acid is a metabolite of benzylpenicillin. It is produced by hydrolysis of when beta-lactam ring of benzylpenicillin. Along with some other metabolites of penicillin, benzylpenilloic acid is responsible for the allergic reaction to beta-lactam antibiotic. It is a component of a minor determinant mixture (MDM) reagent which is used to evaluate sensitivity to penicillin in the clinic.

Ezogabine (U.S. adopted name) or retigabine (international nonproprietary name) is one of a family of aminopyrroles with anticonvulsant activity. It is used as an adjunctive treatment for partial epilepsies in treatment-experienced adult patients. The drug was approved by the European Medicines Agency under the trade name Trobalt and by the United States Food and Drug Administration (FDA), under the trade name Potiga. The mechanism by which ezogabine exerts its therapeutic effects has not been fully elucidated. In vitro studies indicate that ezogabine enhances transmembrane potassium currents mediated by the KCNQ (Kv7.2 to 7.5) family of ion channels. By activating KCNQ channels, ezogabine is thought to stabilize the resting membrane potential and reduce brain excitability. This mechanism of action is unique among antiepileptic drugs, and may hold promise for the treatment of other neurologic conditions, including migraine, tinnitus and neuropathic pain. In vitro studies suggest that ezogabine may also exert therapeutic effects through augmentation of GABA-mediated currents.

Amdinocillin is a novel, semisynthetic penicillin effective against many gram-negative bacteria. The antibacterial activity of amdinocillin is derived from its ability to bind specifically and avidly to Penicillin Binding Protein-2 (PBP 2). Amdinocillin is active alone against many gram-negative organisms. Pseudomonas and non-fermenting gram-negative bacteria, however, are usually resistant. Amdinocillin, in combination with many beta-lactams, exhibits marked synergy against many enterobacteriaceae. No such synergy can be demonstrated for gram-positive organisms or pseudomonas species. Amdinocillin is not beta-lactamase stable. Organisms which produce high levels of plasma-mediated beta-lactamase are resistant to the drug. Used in the treatment of urinary tract infections caused by some strains of E. coli and klebsiella and enterobacter species. Used mainly against Gram negative organisms. Amdinocillin is not available in the United States.

Azlocillin is a semisynthetic penicillin with broad spectrum of anti-bacterial action. The drug is effective against gram-negative and gram-positive infections and acts by inhibition of penicillin-binding protein (PBP)-dependent bacterial cell wall synthesis. Azlocillin was marketed in the USA under the name Azlin (sodium salt), however, its approval was discontinued.