Sulfonamides play an antibacterial role by competing with PABA for dihydrofolate synthase and hindering the synthesis of folic acid in sensitive bacteria. They are effective against most Gram-positive bacteria and some Gram-negative bacteria. Sulfonamides have no effect on synthesized folic acid, so the effect is slow. Bacteria that can use exogenous folic acid are not sensitive to sulfonamides. Livestock and poultry cells can directly use folic acid, so they are not easily harmed by sulfonamides blocking folic acid synthesis. The minimum effective concentration in the blood is 5mg/100ml, and severe infections require 10-15mg/100ml.

It has a peripheral anti-M cholinergic receptor effect, can relieve smooth muscle spasm caused by acetylcholine, can also relieve microvascular spasm, improve microcirculation, relax gastrointestinal smooth muscle and inhibit its peristalsis; its effect is slightly weaker than atropine, and its effect of inhibiting digestive gland secretion is 1/10 of atropine; its effect of inhibiting saliva secretion and dilating the pupil is weaker, which is 1/20-1/10 of atropine; because it is not easy to pass through the blood-cerebrospinal fluid barrier, its central effect is also weaker than atropine.

It can cause blood vessels to contract, reduce capillary permeability, enhance platelet aggregation and adhesion, promote platelets to release coagulation active substances, shorten coagulation time, and achieve hemostatic effect.

This product is an antibacterial and anti-inflammatory drug. Its mechanism is to inhibit bacterial dihydrofolate reductase and hinder bacterial folic acid metabolism. When used in combination with sulfonamides, it can double hinder bacterial metabolism, thereby enhancing the antibacterial effect. When used in combination with certain antibiotics, it also has a synergistic effect, so it is used as a synergist for sulfonamides and certain antibiotics.

Calcium supplements. Calcium ions can maintain normal excitability of nerves and muscles and promote the secretion of acetylcholine at nerve endings. When serum calcium is low, neuromuscular excitability may increase, resulting in convulsions. When blood calcium is too high, excitability decreases, resulting in weakness. Calcium ions can improve the permeability of cell membranes, increase the density of capillaries, reduce exudation, and have an anti-allergic effect. Calcium ions can promote the calcification of bones and teeth. There is a competitive antagonism between high concentrations of calcium and magnesium ions, which can be used to rescue magnesium poisoning. Calcium ions can react with fluoride to form insoluble calcium fluoride, which can be used to rescue fluoride poisoning.