Chemical Name: Trimethoprim (TMP)
EINECS No.: 212-006-2
Molecular Weight: 290.32
Appearance: White or yellowish-white powder
The antibacterial spectrum of trimethoprim is similar to sulfamethoxazole isoxazole, and the antibacterial effect is 20~100 times stronger than sulfamethoxazole isoxazole, but it is easy to produce drug resistance when used alone and combined with sulfonamides. Trimethoprim is a bacteriostatic agent when used alone, synergistic with sulfonamide drugs, or even bactericidal. If the bacteria are sensitive to the two drugs alone, the subinhibitory concentration of one drug can reduce the MIC4 to 8 times of the other drugs. But the synergistic effect is different in different bacteria or strains. It has a high synergistic effect in Neisseria gonorrhoeae and Proteus. In most Staphylococcus, Streptococcus, pneumococcus, influenza bacteria only synergy 4~8 times. The maximum synergistic concentration was produced by the respective MIC coordination.
Some strains are sensitive to the two drugs but do not produce synergistic effects. If the bacteria are resistant to sulfonamides, they are sensitive only to trimethoprim, and generally do not produce synergy. It is only equivalent to TMP alone, such as the high concentration of sulfonamides, and a synergistic effect in vitro. This is of little clinical significance, because sulfonamide dosage is too large to be safe, but it may be beneficial for urinary tract infection, because sulfonamide is highly concentrated in urine. For example, Pseudomonas aeruginosa is moderately resistant to sulfonamide, and synergistic antibacterial effects may occur when combined with trimethoprim. Domestic studies have proved that trimethoprim has synergistic effects on various antibiotics. For example, the synergistic effect of combined with tetracycline on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa is greater than the combination of sulfamethoxazole, and to drug resistant Staphylococcus aureus and trimethoprim can enhance penicillin, neomycin II and erythromycin, and Candida aeruginosa and kanamycin can be enhanced for Pseudomonas aeruginosa. The effect of mycin.
However, some people believe that trimethoprim should not be used in conjunction with tetracycline, doxycycline, kanamycin or gentamycin. It has been reported that Streptococcus pyogenes, Enterococcus, proteus, Klebsiella, Escherichia coli and Pseudomonas aeruginosa are the most effective synergistic agents abroad. Animal experiments also confirm that the survival rate of infected mice can be increased. Rifampicin or trimethoprim resistant strains can also be synergistic. The commonly used amount of the two drugs can reach the level of synergism in the patients. Sulfonamide and polymyxin have synergistic effect on negative bacilli. The addition of trimethoprim is better. The drug resistance of trimethoprim during the treatment is still rare, about 10%. This may be the combination of TMP and sulfonamide drugs, and the susceptible pathogens are not susceptible to drug resistance. However, only TMP sensitive pathogens are susceptible to drug resistance. In the laboratory, it is also proved that the resistance of negative bacteria to TMP is developing rapidly, and the resistance to antibiotics will increase as a result of clinical application.
white or yellowish-white powder
very slightly soluble in water, soluble in bencyl alcohol, moderately in chloroform and methanol, slightly in alcohol and acetone, practically insoluble in ether and carbon tetrachloride
a (1975), compare trimethoprim crs
in accordance with the ref. standard ir spectrum
b (741), max.287nm, not differ in more than 3%
melting point (741)
≤ 0.2 %
＜ 0.2 %
≤ 0.1 %
loss on drying (731)
≤ 0.5 %
residue on ignition (281)
≤ 0.1 %
impurity k (aniline)
98.5 %～101.0 %
this product meets the requirements of usp38.