This product is a first-generation cephalosporin with a broad antibacterial spectrum and strong activity against Gram-positive bacteria. Penicillinase-producing and non-penicillinase-producing Staphylococcus aureus, coagulase-negative Staphylococcus, Streptococcus pyogenes, Streptococcus pneumoniae, Group B hemolytic Streptococcus, Streptococcus viridans, Staphylococcus epidermidis, Corynebacterium diphtheriae, and Bacillus anthracis are all quite sensitive to this product. Enterococci, methicillin-resistant Staphylococcus, Listeria, and Nocardia are resistant. Haemophilus influenzae, Neisseria meningitidis, Moraxella catarrhalis, and Neisseria gonorrhoeae are highly sensitive to this product. Some strains of Escherichia coli, Klebsiella, Salmonella, Shigella, and Proteus are moderately sensitive to this product, while most of the other Gram-negative rods are resistant. Gram-positive anaerobic bacteria are sensitive to this product, and Bacteroides fragilis is resistant to this product. This product mainly inhibits the synthesis of bacterial cell walls.

This product is an oral selective histamine H1 receptor antagonist. It has no obvious anticholinergic and anti-5-hydroxytryptamine effects, and has a small central nervous system inhibitory effect.

It belongs to the 14-membered macrolide antibiotics. It inhibits protein synthesis by blocking the association of the 50S subunit of the nucleoprotein and producing an antibacterial effect. It has a slightly better antibacterial effect on Gram-positive bacteria such as Streptococcus, Pneumococcus, and Staphylococcus than erythromycin, and also has certain antibacterial activity against induced erythromycin-resistant strains. Clarithromycin and its metabolites have enhanced antibacterial effects on Haemophilus influenzae, have certain effects on gonococci, Listeria, and Campylobacter jejuni, and have stronger effects on Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia trachomatis, Ureaplasma urealyticum, etc. than erythromycin, with MIC90 of about 0.008-0.12 mg/L. In addition, it has certain activity against Borrelia burgdorferi, Mycobacterium avium, Toxoplasma gondii, etc., and most of them are better than other varieties. In addition to having a strong antibacterial effect on anaerobic cocci, it is better than erythromycin on Bacteroides fragilis. The antibiotic after-effect on Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, etc. is significantly stronger than erythromycin. Its antibacterial activity in vitro is similar to that of erythromycin, but its antibacterial activity in vivo against some bacteria such as Staphylococcus aureus, Streptococcus, Haemophilus influenzae, etc. is stronger than that of erythromycin. There is cross-resistance between it and erythromycin.

The third generation of oral cephalosporins kill bacteria by inhibiting bacterial cell wall synthesis. They are stable to most β-lactamases, and many strains producing penicillinase and cephalosporinase are still sensitive to them. They have good antibacterial effects on Gram-positive cocci such as pneumococci and Streptococcus pyogenes, and Gram-negative bacilli such as Haemophilus influenzae (including enzyme-producing strains), Moraxella catarrhalis (including enzyme-producing strains), Escherichia coli, Proteus mirabilis, and Neisseria gonorrhoeae (including enzyme-producing strains). In vitro, they also have antibacterial activity against Streptococcus pneumoniae, Parainfluenzae, Proteus vulgaris, Klebsiella pneumoniae, Pasteurella multocida, Providencia, Salmonella, Shigella, Serratia marcescens, Citrobacter heteromorphis, and Citrobacter malonate, but their clinical effectiveness has not yet been established. They have poor antibacterial effects on Staphylococcus, and have no antibacterial effects on Pseudomonas aeruginosa, Enterobacter, Bacteroides fragilis, Clostridium, etc.

The third generation of oral cephalosporins kills bacteria by inhibiting bacterial cell wall synthesis and is stable to most β-lactamases. It has good antibacterial effects on Gram-positive cocci such as pneumococci and Streptococcus pyogenes, and Gram-negative bacilli such as Haemophilus influenzae (including enzyme-producing strains), Moraxella catarrhalis (including enzyme-producing strains), Escherichia coli, Proteus mirabilis, and Neisseria gonorrhoeae (including enzyme-producing strains). It also has antibacterial activity in vitro against Streptococcus pneumoniae, Parainfluenzae, Proteus vulgaris, Klebsiella pneumoniae, Pasteurella multocida, Providencia, Salmonella, Shigella, Serratia marcescens, Citrobacter heteromorphis, and Citrobacter malonate. It has poor antibacterial effects on Staphylococcus, and has no antibacterial effects on Pseudomonas aeruginosa, Enterobacter, Bacteroides fragilis, Clostridium, etc.