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.

Cephalexin is a semisynthetic cephalosporin antibiotic intended for oral administration. In vitro tests demonstrate that the cephalosporins are bactericidal because of their inhibition of cell-wall synthesis. Cephalexin has been shown to be active against most strains of the following microorganisms both in vitro: Staphylococcus aureus (including penicillinase-producing strains), Streptococcus pneumoniae (penicillin-susceptible strains), Streptococcus pyogenes, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Moraxella (Branhamella) catarrhalis, Proteus mirabilis. Cephalexin is indicated for the treatment of the respiratory tract, skin and skin structure, bone and genitourinary tract infections when caused by susceptible strains of the designated microorganisms.

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.

Cefprozil is a 2nd generation cephalosporin that is FDA approved for the treatment of mild to moderate infections of upper respiratory tract, lower respiratory tract, and uncomplicated skin and skin-structure infections. Cefprozil, like the penicillins, is a beta-lactam antibiotic. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, it inhibits the third and last stage of bacterial cell wall synthesis. Common adverse reactions include diarrhea, nausea, vomiting, dizziness, abdominal pain and vaginitis. Nephrotoxicity has been reported following concomitant administration of aminoglycoside antibiotics and cephalosporin antibiotics. Concomitant administration of probenecid doubled the AUC for cefprozil.