Pharmacological action This product is levorotatory of ofloxacin, and its antibacterial activity is about twice that of ofloxacin. Its main mechanism is to inhibit the activity of bacterial DNA gyrase (bacterial topoisomerase ⅱ) and hinder the replication of bacterial DNA, thus achieving antibacterial effect. This product has the characteristics of broad antibacterial spectrum and strong antibacterial effect, and has strong antibacterial activity against most Enterobacteriaceae bacteria, such as Escherichia coli, Klebsiella, Serratia, Proteus, Shigella, Salmonella, Citrobacter, Acinetobacter, Pseudomonas aeruginosa, Haemophilus influenzae, Neisseria gonorrhoeae and other gram-negative bacteria. It also has a good antibacterial effect on some methicillin-sensitive staphylococcus, streptococcus pneumoniae, streptococcus pyogenes, streptococcus hemolyticus and other gram-positive bacteria and Legionella, mycoplasma and chlamydia, but it has a poor antibacterial effect on anaerobic bacteria and enterococci. Toxicological study of repeated administration: Rats were given this product orally at the doses of 50, 200 and 800mg/kg for 4 weeks, but only 800mg/kg group showed neutropenia and increased M/E of bone marrow. Histopathology showed slight degeneration of the joint surface of limbs. After 4 weeks of oral administration to rhesus monkeys, animals in the dosage group of 100mg/kg showed salivation, diarrhea, slight weight loss and increased urine pH value. After 26 weeks of oral administration to rats, the pH values of drooling and urine in 80 and 320mg/kg dose groups increased. In the 320mg/kg group, the fecal output increased and the goblet cells of cecum mucosa swelled. After 26 weeks of oral administration to rhesus monkeys, there was no obvious toxic reaction at the doses of 10, 25 and 62.5mg/kg. Effects on articular cartilage: Young and 3-4-week-old rats and 4-month-old Beagle dogs were given orally for 7 days. When the dosage of rats was above 300mg/kg and Beagle dogs were above 10mg/kg, articular cartilage lesions appeared, and young and young Beagle dogs were prone to joint toxicity. Dogs aged 1.3 months showed extremely slight combined toxicity at a dose of 40mg/kg after 7 days of oral administration. However, for 18-month-old dogs, intravenous injection of 14 days, at the dose of 30mg/kg, has no joint toxicity. Reproductive toxicity: When the oral dose reaches 360mg/kg before pregnancy and early pregnancy, it has no effect on the reproductive capacity and fetus of female and male animals. The dose of 90mg/kg during organogenesis in rats has no obvious effect on fetuses and newborns. When rabbits take 50mg/kg orally, there is no embryo and fetus death, fetal growth retardation and teratogenesis. Oral administration of 360mg/kg to perinatal and lactating rats has no obvious effect on delivery, lactation and newborn of animals. Phototoxicity: Taking the change of mouse auricle thickness as an index, the phototoxicity was studied by long-wave ultraviolet (320-400 nm). Results When the oral dose reached 200mg/kg, there was no obvious abnormal change.