Cephalexin is a first-generation cephalosporin with an antibacterial spectrum similar to that of cephalothin, but its antibacterial activity is poorer than that of the latter. Except for Enterococcus and methicillin-resistant Staphylococci, most strains of Streptococcus pneumoniae, hemolytic Streptococcus, and Staphylococcus aureus that produces or does not produce penicillinase are sensitive to this product. This product has a good antibacterial effect on Neisseria, but Haemophilus influenzae is less sensitive to this product; this product has a certain antibacterial effect on some Escherichia coli, Proteus mirabilis, Salmonella and Shigella. The remaining Enterobacteriaceae, Acinetobacter, Pseudomonas aeruginosa, and Bacteroides fragilis are resistant to this product. Fusobacterium and Veillonella are generally sensitive to this product, and anaerobic Gram-positive cocci are moderately sensitive to this product.

Cephalexin is a first-generation cephalosporin with an antibacterial spectrum similar to that of cephalothin, but its antibacterial activity is poorer than that of the latter. Except for Enterococcus and methicillin-resistant Staphylococci, most strains of Streptococcus pneumoniae, hemolytic Streptococcus, and Staphylococcus aureus that produces or does not produce penicillinase are sensitive to this product. This product has a good antibacterial effect on Neisseria, but Haemophilus influenzae is less sensitive to this product; this product has a certain antibacterial effect on some Escherichia coli, Proteus mirabilis, Salmonella and Shigella. The remaining Enterobacteriaceae, Acinetobacter, Pseudomonas aeruginosa, and Bacteroides fragilis are resistant to this product. Fusobacterium and Veillonella are generally sensitive to this product, and anaerobic Gram-positive cocci are moderately sensitive to this product. The oral median lethal dose of cephalexin in mice is 2600 mg/kg.

In vivo, it competitively inhibits the rate-limiting enzyme hydroxymethylglutaryl coenzyme A reductase in the cholesterol synthesis process, reducing the synthesis of cholesterol and increasing the synthesis of low-density lipoprotein receptors. Its main site of action is in the liver, resulting in lower blood cholesterol and low-density lipoprotein cholesterol levels, thereby playing a role in the prevention and treatment of atherosclerosis and coronary heart disease. This product also reduces serum triglyceride levels and increases blood high-density lipoprotein levels.

Cefotaxime is a third-generation cephalosporin with a broad antibacterial spectrum. It has strong activity against Gram-negative bacteria such as Escherichia coli, Proteus mirabilis, Klebsiella and Salmonella, and other Enterobacteriaceae. It also has a good effect on Proteus vulgaris and Citrobacter. Enterobacter cloacae and Enterobacter aerogenes are relatively resistant to this product. This product has no antibacterial activity against Pseudomonas aeruginosa and Alcaligenes. Cefotaxime has a strong effect on influenza bacilli, Neisseria gonorrhoeae (including beta-lactamase-producing strains), Neisseria meningitidis and Moraxella catarrhalis. This product has poor antibacterial activity against Staphylococcus aureus, strong activity against Gram-positive cocci such as hemolytic Streptococcus and Streptococcus pneumoniae, and Enterococcus is resistant to this product.

Cefotaxime is a third-generation cephalosporin with a broad antibacterial spectrum. It has strong activity against Gram-negative bacteria such as Escherichia coli, Proteus mirabilis, Klebsiella and Salmonella, and other Enterobacteriaceae. It also has a good effect on Proteus vulgaris and Citrobacter. Enterobacter cloacae and Enterobacter aerogenes are relatively resistant to this product. This product has no antibacterial activity against Pseudomonas aeruginosa and Alcaligenes. Cefotaxime has a strong effect on influenza bacilli, Neisseria gonorrhoeae (including beta-lactamase-producing strains), Neisseria meningitidis and Moraxella catarrhalis. This product has poor antibacterial activity against Staphylococcus aureus, strong activity against Gram-positive cocci such as hemolytic Streptococcus and Streptococcus pneumoniae, and Enterococcus is resistant to this product.