Spectinomycin is an antibiotic produced by Streptomyces spectabilis. It is active against gram-negative bacteria and used for the treatment of acute gonorrheal urethritis and proctitis in the male and acute gonorrheal cervicitis and proctitis in the female when due to susceptible strains of Neisseria gonorrhoeae. In vitro studies have shown spectinomycin to be active against most strains of Neisseria gonorrhoeae (minimum inhibitory concentration <7.5 to 20 mcg/mL). Footprint studies indicate that spectinomycin exerts regional effects on ribosomal structure. Spectinomycin hydrochloride is an inhibitor of protein synthesis in the bacterial cell; the site of action is the 30S ribosomal subunit. The antibiotic is not significantly bound to plasma protein. Spectinomycin was discovered 1961. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. This antibiotic is no longer available in the United States. Pfizer has discontinued distribution of spectinomycin (Trobicin) in the U.S. The drug continues to be distributed outside the U.S.

Carfecillin is a phenyl ester of the side-chain carboxyl group of carbenicillin, beta-lactam antibiotic, acting as a prodrug. Upon oral administration, is broken down in the intestinal mucosa to the active antibacterial. It is used for urinary tract infections.

Cephaloridine (or cefaloridine) is a first generation semisynthetic derivative of cephalosporin C. It is unique among cephalosporins in that it exists as a zwitterion. It is of semi synthetic origin and belongs to cephem carboxylate. It belongs to Peptidoglycan synthesis inhibitor pharmacological group on the basis of mechanism of action. Since the discovery of cephalosporins P, N and C in 1948 there have been many studies describing the antibiotic action of cephalosporins and the possibility to synthesize derivatives. Hydrolysis of cephalosporin C, isolation of 7-aminocephalosporanic acid and the addition of side chains opened the possibility to produce various semi-synthetic cephalosporins. In 1962, cephalothin and cephaloridine were introduced. Cephaloridine is very active against gram positive cocci and used in a large variety of bacterial infections, such as respiratory tract, skin and urinary tract infections. Cephaloridine is primarily indicated in conditions like Bacterial infections, Bronchitis, Gonorrhoea, and can also be given in adjunctive therapy as an alternative drug of choice in Corneal ulcers, Intraocular infections. Cephaloridine was temporarily popular because it was better tolerated intramuscularly and attained in higher and more sustained levels in blood than cephalothin. Because it is also poorly absorbed after oral administration the use of this drug for humans declined rapidly, especially since the second generation of cephalosporins was introduced in the 1970s. Today it is more commonly used in veterinary practice to treat mild to severe bacterial infections caused by penicillin resistant and penicillin sensitive Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Streptococcus pneumoniae, Bacillus sutbtilis, Klebsiella, Clostridium diptheriae, Salmonella and Shigella. Before the 1970s, cephaloridine was used to treat patients with urinary tract infections. Besides the drug has been used successfully in the treatment of various lower respiratory tract infections. Cephaloridine was very effective to cure pneumococcal pneumonia. It has a high clinical and bacteriological rate of success in staphylococcal and streptococcal infections.

Methacycline is a tetracycline antibiotic. Similar to other tetracyclines, it has a wide spectrum of antimicrobial action. It is active against most Gram-positive bacteria (pneumococci, streptococci, staphylococci) and Gram-negative bacteria (E. coli, salmonella, shigella, etc.), and towards agents causing onithosis, psittacosis, trachoma, and some Protozoa. Like other tetracyclines, the general usefulness of methacycline has been reduced with the onset of bacterial resistance. Methacycline inhibits the binding of aminoacyl-tRNA to the mRNA-ribosome complex. Methacycline inhibits cell growth by inhibiting translation. It binds to the 16S part of the 30S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome. Methacycline is mostly used for the treatment of acute bacterial exacerbations of chronic bronchitis.

Cloxacillin is a derivative of penicillin for the treatment of broad spectrum of bacterial infections. The drug exerts its action by inhiiting bacterial beta-lactamase (penicillin-binding proteins).

Nalidixic acid is a quinolone antibacterial indicated for the treatment of urinary tract infections. Nalidixic acid has marked antibacterial activity against gram-negative bacteria including Enterobacter species, Escherichia coli, Morganella Morganii; Proteus Mirabilis, Proteus vulgaris, and Providencia rettgeri. Pseudomonas species are generally resistant to the drug. It is suggested that nalidixic acid acts by inhibiting bacterial DNA gyrase.

Cephalothin is a first generation, semisynthetic analogue of natural cephalosporin antibiotic. The in-vitro bactericidal action of Cephalothin results from inhibition of cell-wall synthesis. In general, Cephalothin has higher activity against Gram positive than Gram negative organisms. Cephalothin is primarily indicated in conditions like bone and joint infection, genitourinary tract infections, respiratory tract infections, soft tissue and skin infections and others. The severe or irreversible adverse effects of Cephalothin, which give rise to further complications, include nephrotoxicity, hemolytic anemia. Cephalothin produces potentially life-threatening effects, which include anaphylaxis, serum sickness syndrome. The symptomatic adverse reactions produced by Cephalothin are: rashes, urticaria, allergic reactions, thrombophlebitis, pain at injection site. Co-administration of diuretics, such as furanthril, ethacrynic acid and nephrotoxic antibiotics may increase the risk of renal damage. Reciprocal inactivation could be observed during in vitro mixing of Cephalothin with aminoglycosides.

Sulfaphenazole is an oral antibiotic, which was used for the treatment of bacterial infections under the name Sulfabid. The drug was found to block folate synthesis in bacterias by inhibiting the enzyme dihydropteroate synthase. Sulfaphenazole is also known to inhibit CYP2C9 with high potency and specificity. Sulfabid is no longer marketed in the USA.

Idoxuridine is an antiviral agent use in keratitis caused by herpes simplex virus. As a prescription drug it comes as a 0.1% ophthalmic solution/drops (Herplex and Dendrid). The first studies of the compound for treatment of human herpes simplex started in early 1960s. Being a structural analog of thymidine idoxuridine inhibits viral DNA replication by substituting thymidine. The effect of idoxuridine results in the inability of the virus to reproduce and/or infect tissues. Idoxuridine also blocks viral thymidine kinase as its substrate analog.

Methicillin sodium anhydrous is a sodium salt of methicillin (methicillin). Methicillin is an antibiotic formerly used in the treatment of bacterial infections caused by organisms of the genus Staphylococcus. Methicillin is a semisynthetic derivative of penicillin. It was first produced in the late 1950s and was developed as a type of antibiotic called penicillinase-resistant penicillin—it contained a modification to the original penicillin structure that made it resistant to a bacterial enzyme called penicillinase (beta-lactamase). Compared to other penicillins that face antimicrobial resistance due to β-lactamase, it is less active, can be administered only parenterally, and has a higher frequency of interstitial nephritis, an otherwise-rare adverse effect of penicillins. However, the selection of meticillin depended on the outcome of susceptibility testing of the sampled infection, and since it is no longer produced, it is also not routinely tested for anymore.