Pyridine is a basic heterocyclic organic compound used as a solvent in organic synthesis. Since the pyridine ring has three double bonds, six p-electrons exist, which are sufficient for aromatic ring formation without involving the lone pair electrons of the nitrogen atom. Since the lone pair electrons remain free, quaternary salts retain the aromaticity. However, the nitrogen atom has a higher electronegativity than the carbon atoms and shows an electron-withdrawing effect. In oxidation and reduction reactions, the pyridine ring exhibits properties characteristic of pelectron-deficient aromatic rings: resistance to oxidation and facile reduction. Pyridine bases are a constituent of tars. They were isolated from coal tar or coal gas before synthetic manufacturing processes became established. Pyridine is an excellent solvent, especially for dehydrochlorination reactions and extraction of antibiotics. Large amounts of pyridine are used as starting material for pharmaceuticals and agrochemicals: for example, herbicides such as diquat and paraquat, insecticides such as chlorpyrifos, and fungicides such as pyrithione. Pyridine is harmful if inhaled, swallowed or absorbed through the skin. Effects of acute pyridine intoxication include dizziness, headache, lack of coordination, nausea, salivation, and loss of appetite.

Loracarbef (KT3777) is carbacephem antibiotic structurally identical to cefaclor, except that the sulfur atom of position 1 of the cephem nucleus has been replaced by carbon. It showed good affinity for penicillin-binding proteins. At low concentrations (< 2 mg/L) in vitro, it inhibits Streptococcus pneumoniae, S. pyogenes, beta-haemolytic streptococci groups B, C and G. Proteus mirabilis and Moraxella catarrhalis, including beta-lactamase-producing strains. At therapeutic plasma concentrations it is also active in vitro against most strains of Staphylococcus aureus, S. saprophyticus, Escherichia coli and beta-lactamase-positive and -negative strains of Haemophilus influenzae. Loracarbef has been indicated in the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms.

Ceftizoxime is a semisynthetic cephalosporin antibiotic, which can be administered intravenously or intramuscularly. It was sold under brand name, cefizox, but was removed from the US Market in 2007. Cefizox was used to treat different infections, such as lower respiratory tract infections caused by Klebsiella spp.; Proteus mirabilis; Escherichia coli; Haemophilus influenza; urinary tract Infections caused by Staphylococcus aureus (penicillinase¬ and nonpenicillinase¬producing); Escherichia coli; Pseudomonas spp. Also for treatment of gonorrhea including uncomplicated cervical and urethral gonorrhea caused by Neisseria gonorrhoeae; pelvic inflammatory disease caused by Neisseria gonorrhoeae, Escherichia coli or Streptococcus agalactiae; meningitis caused by Haemophilus influenza. In addition, some others infections. Cefizox has also been used successfully in the treatment of a limited number of pediatric and adult cases of meningitis caused by Streptococcus pneumoniae. Infections caused by aerobic gram ¬negative and by mixtures of organisms resistant to other cephalosporins, aminoglycosides, or penicillins have responded to treatment with Cefizox. The bactericidal action of ceftizoxime results from inhibition of the third and last stage of bacterial cell wall synthesis. Bacterial cell wall autolytic enzymes such as autolysins then mediate cell lysis; it is possible that ceftizoxime interferes with an autolysin inhibitor. Ceftizoxime is highly resistant to a broad spectrum of beta -lactamases (penicillinase and cephalosporinase), including Richmond types II, III, TEM, IV, produced by both aerobic and anaerobic gram - positive and gram - negative organisms and I.

Cefixime, an antibiotic, is a third-generation cephalosporin like ceftriaxone and cefotaxime. Cefixime is highly stable in the presence of beta-lactamase enzymes. As a result, many organisms resistant to penicillins and some cephalosporins due to the presence of beta-lactamases, may be susceptible to cefixime. The antibacterial effect of cefixime results from inhibition of mucopeptide synthesis in the bacterial cell wall. Like all beta-lactam antibiotics, cefixime binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, causing the inhibition of the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that cefixime interferes with an autolysin inhibitor. Cefixime is sold under the brand name Suprax, indicated for the treatment of: Uncomplicated Urinary Tract Infections Otitis Media Pharyngitis and Tonsillitis Acute Exacerbations of Chronic Bronchitis Uncomplicated Gonorrhea (cervical/urethral)

Ceftazidime is a semisynthetic, broad-spectrum, beta-lactam antibiotic, used especially for Pseudomonas and other gram-negative infections in debilitated patients. Ceftazidime is used to treat lower respiratory tract, skin, urinary tract, blood-stream, joint, and abdominal infections, and meningitis. The drug is given intravenously (IV) or intramuscularly (IM) every 8–12 hours (two or three times a day), with dose and frequency varying by the type of infection, severity, and/or renal function of the patient. Injectable formulations of ceftazidime are currently nebulized "off-label" to manage Cystic Fibrosis, non-Cystic Fibrosis bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Ceftazidime is generally well-tolerated. When side effects do occur, they are most commonly local effects from the intravenous line site, allergic reactions, and gastrointestinal symptoms. According to one manufacturer, in clinical trials, allergic reactions including itching, rash, and fever, happened in fewer than 2% of patients. Rare but more serious allergic reactions, such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme, have been reported with this class of antibiotics, including ceftazidime. Gastrointestinal symptoms, including diarrhea, nausea, vomiting, and abdominal pain, were reported in fewer than 2% of patients.

Ceftazidime is a semisynthetic, broad-spectrum, beta-lactam antibiotic, used especially for Pseudomonas and other gram-negative infections in debilitated patients. Ceftazidime is used to treat lower respiratory tract, skin, urinary tract, blood-stream, joint, and abdominal infections, and meningitis. The drug is given intravenously (IV) or intramuscularly (IM) every 8–12 hours (two or three times a day), with dose and frequency varying by the type of infection, severity, and/or renal function of the patient. Injectable formulations of ceftazidime are currently nebulized "off-label" to manage Cystic Fibrosis, non-Cystic Fibrosis bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Ceftazidime is generally well-tolerated. When side effects do occur, they are most commonly local effects from the intravenous line site, allergic reactions, and gastrointestinal symptoms. According to one manufacturer, in clinical trials, allergic reactions including itching, rash, and fever, happened in fewer than 2% of patients. Rare but more serious allergic reactions, such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme, have been reported with this class of antibiotics, including ceftazidime. Gastrointestinal symptoms, including diarrhea, nausea, vomiting, and abdominal pain, were reported in fewer than 2% of patients.

Ceftazidime is a semisynthetic, broad-spectrum, beta-lactam antibiotic, used especially for Pseudomonas and other gram-negative infections in debilitated patients. Ceftazidime is used to treat lower respiratory tract, skin, urinary tract, blood-stream, joint, and abdominal infections, and meningitis. The drug is given intravenously (IV) or intramuscularly (IM) every 8–12 hours (two or three times a day), with dose and frequency varying by the type of infection, severity, and/or renal function of the patient. Injectable formulations of ceftazidime are currently nebulized "off-label" to manage Cystic Fibrosis, non-Cystic Fibrosis bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Ceftazidime is generally well-tolerated. When side effects do occur, they are most commonly local effects from the intravenous line site, allergic reactions, and gastrointestinal symptoms. According to one manufacturer, in clinical trials, allergic reactions including itching, rash, and fever, happened in fewer than 2% of patients. Rare but more serious allergic reactions, such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme, have been reported with this class of antibiotics, including ceftazidime. Gastrointestinal symptoms, including diarrhea, nausea, vomiting, and abdominal pain, were reported in fewer than 2% of patients.

Cefaclor is a semisynthetic cephalosporin antibiotic for oral administration. As with other cephalosporins, the bactericidal action of Cefaclor results from inhibition of cell-wall synthesis. Cefaclor is indicated in the treatment of the following infections when caused by susceptible strains of the designated microorganisms: Otitis media caused by Streptococcus pneumoniae, Haemophilus influenzae, staphylococci, and Streptococcus pyogenes; Lower respiratory tract infections, including pneumonia, caused by Streptococcus pneumoniae, Haemophilus influenzae, and Streptococcus pyogenes; Pharyngitis and Tonsillitis, caused by Streptococcus pyogenes; Urinary tract infections, including pyelonephritis and cystitis, caused by Escherichia coli, Proteus mirabilis, Klebsiella spp., and coagulase-negative staphylococci; Skin and skin structure infections caused by Staphylococcus aureus and Streptococcus pyogenes. Adverse effects considered to be related to therapy with cefaclor are: Hypersensitivity reactions, Rarely, reversible hyperactivity, agitation, nervousness, insomnia, confusion, hypertonia, dizziness, hallucinations, somnolence and diarrhea. Patients receiving Cefaclor may show a false-positive reaction for glucose in the urine with tests that use Benedict's and Fehling's solutions and also with Clinitest® tablets. There have been reports of increased anticoagulant effect when Cefaclor and oral anticoagulants were administered concomitantly.