It inhibits bacterial DNA gyrase and topoisomerase IV, thereby inhibiting bacterial DNA replication, transcription and repair processes. It has antibacterial activity against the following microorganisms: Gram-positive bacteria (such as Staphylococcus aureus, Streptococcus pneumoniae), Gram-negative bacteria (such as Escherichia coli, Haemophilus influenzae and parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Neisseria gonorrhoeae, Proteus mirabilis) and other microorganisms (such as Chlamydia pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae).

1. Pharmacological action Gatifloxacin is a racemic compound of the 8-methoxyfluoroquinolone class. It has a broad spectrum of activity against Gram-negative and Gram-positive microorganisms in vitro. Its R- and S-enantiomers have the same antibacterial activity. The antibacterial effect of this product is through inhibiting bacterial DNA gyrase and topoisomerase IV, thereby inhibiting the replication, transcription and repair process of bacterial DNA. Both in vitro tests and clinical use results show that this product has antibacterial activity against most strains of the following microorganisms: (1) Gram-positive bacteria: Staphylococcus aureus (limited to strains sensitive to methicillin), Streptococcus pneumoniae (strains sensitive to penicillin). (2) Gram-negative bacteria: Escherichia coli, Haemophilus influenzae and parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Neisseria gonorrhoeae, Proteus mirabilis. (3) Other microorganisms: Chlamydia pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae. 2. Toxicological studies (1) Genotoxicity: This product has no mutagenic effect on multiple strains in the Ames test, but has a mutagenic effect on Salmonella strain TA102 in vitro. The results of the gene mutation test of Chinese hamster V79 cells and the genetic test of Chinese hamster CHL/IU cells were both positive. Similar results can also be seen in other quinolone drugs, which may be due to the inhibitory effect of this product on type II DNA topoisomerase of eukaryotes at high concentrations. The results of the mouse micronucleus test, rat cytogenetic test and rat DNA repair test of this product administered orally and intravenously were all negative. (2) Reproductive toxicity: The oral dose of rats was up to 200 mg/kg (equivalent to the maximum recommended dose for humans based on daily systemic exposure (AUC)), and there was no adverse effect on rat fertility and reproduction. The oral doses of rats and rabbits were 150 mg/kg and 50 mg/kg respectively (about 0.7 and 1.9 times the maximum recommended dose for humans based on AUC), and no teratogenic effect was observed. However, during the period of organogenesis, oral or intravenous administration of 200 mg/kg and 60 mg/kg, respectively, can cause fetal skeletal malformations in rats; oral or intravenous administration of ≥150 mg/kg and ≥30 mg/kg, respectively, can cause delayed fetal skeletal ossification, including the appearance of corrugated ribs. This indicates that there is mild fetal toxicity at this dose. This toxicity can also be seen in other quinolones. Rats were given oral doses of 200 mg/kg in the initial stage of late pregnancy and continued to be administered until lactation, and increased post-implantation embryo loss and neonatal and perinatal mortality were observed. These findings also suggest the fetal toxicity of this product. Since there are no adequate and rigorous studies conducted in pregnant women, this product can only be used during pregnancy when the potential clinical benefits of this product to the mother outweigh the harm to the fetus. This product can be secreted from rat milk, but it is not known whether it can be secreted from human milk. Since many drugs can be secreted from human milk, it should be used with caution in breastfeeding women. (3) Carcinogenicity: B6C3F1 mice were administered with the drug for 18 months, with the doses for female and male animals being 90 mg/kg and 81 mg/kg, respectively [based on daily systemic exposure (AUC), approximately 0.13 and 0.18 times the maximum recommended human dose]; Fischer344 rats were administered with the drug for 2 years, with the doses for female and male animals being 139 mg/kg and 47 mg/kg, respectively (based on AUC, approximately 0.81 and 0.36 times the maximum recommended human dose). The results did not indicate that this product has the effect of promoting tumor growth. However, when the dose of male animals reached 100 mg/kg (based on AUC, approximately 0.74 times the maximum recommended human dose), the incidence of giant granulocyte lymphoblastic (LGL) leukemia was increased compared with the control group. Although this increase was slightly higher than the range of historical controls, it cannot be considered that these findings at high doses in male animals will affect the safety of this product in clinical use.

It can offset the compensatory mechanism induced by diuretics, enhance the antihypertensive effect of diuretics, selectively block AT1 subtype receptors to exert antihypertensive effects, and weaken the increase in serum uric acid and decrease in blood potassium induced by hydrochlorothiazide.

It can cause activation of the sympathetic nervous system and renin-angiotensin system, counteract the antihypertensive effect, and reduce blood potassium levels; combined use with irbesartan can enhance the antihypertensive effect.

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels

Antidepressant effect; lowers blood pressure, dilates blood vessels