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Antimicrobial Name： Trimethoprim (Proloprim, Trimpex)
CAS Number： 738-70-5
Type of Antibiotic： Sulfonamides
Functional Category： Antibiotic
Molecular Weight： 290.32
Appearance： White to cream, bitter crystalline powder
Mechanism of Action： Trimethoprim (Proloprim, Trimpex) binds to bacterial dihydrofolate reductase, subsequently interfering with the uptake of p-aminobenzoic acid (PABA) into folic acid. As folic acid is a coenzyme responsible for the transport of one-carbon fragments from one molecule to another, it is an essential component of bacterial development. Sulfonamides inhibit bacterial dihydrofolate synthetase, the enzyme immediately preceding dihydrofolate reductase, and therefore act synergistically with trimethoprim.
Chemical Formula：

C14H18N4O3
Solubility：

13.86 in g/100 ml DMAC at 25°

7.29 in g/100 ml benzyl alcohol at 25°

2.57 in g/100 ml propylene glycol at 25°

1.82 in g/100 ml chloroform at 25°

1.21 in g/100 ml methanol at 25°

0.04 in g/100 ml water at 25°

0.003 in g/100 ml ether at 25°

0.002 in g/100 ml benzene at 25°
Melting point：

199 - 203°C (DEC: 285°C)
Resistance Genes：

dfrA: trimethoprim resistant dihydrofolate reductase

dfrK: trimethoprim-resistant dihydrofolate reductase

folA: dihydrofolate reductase type I, trimethoprim resistance

dhfrI: trimethoprim-resistant dihydrofolate reductase

dfra1: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra10: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra12: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra13: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra14: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra15: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra16: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra17: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra19: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra20: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra21: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra22: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra23: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra24: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra25: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra26: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra5: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfra7: Group A drug-insensitive dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfrb1: Group B drug-insensitive R67 dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfrb2: Group B drug-insensitive R67 dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfrb3: Group B drug-insensitive R67 dihydrofolate reductase, which can not be inhibited by trimethoprim.

dfrb6: Group B drug-insensitive R67 dihydrofolate reductase, which can not be inhibited by trimethoprim.
Comments：

Trimethoprim (Proloprim, Trimpex) is a bacteriostatic antibiotic mainly used in the prophylaxis and treatment of urinary tract infections. It belongs to the class of chemotherapeutic agents known as dihydrofolate reductase inhibitors.