The name imidazole was coined in 1887 by the German chemist Arthur Rudolf Hantzsch (1857–1935)

Imidazole is an organic compound with the formula C3N2H4. It is a white or colourless solid that is soluble in water,
producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole,
and having non-adjacent nitrogen atoms. When fused to a pyrimidine ring, it forms purine, which is
the most widely occurring nitrogen-containing heterocycle in nature.

Many natural products, especially alkaloids, contain the imidazole ring. These imidazoles share the 1,3-C3N2
ring but feature varied substituents. This ring system is present in important biological building blocks,
such as histidine and the related hormone histamine. Many drugs contain an imidazole ring, such as certain
antifungal drugs, the nitroimidazole series of antibiotics, and the sedative midazolam.


5-Nitroimidazole is an organic compound with the formula O2NC3H2N2H. The nitro group at position 5 on the
imidazole ring is the most common positional isomer. The term nitroimidazole also refers to
a class of antibiotics that share similar chemical structures.

The killing action of such drugs as metronidazole requires the reduction of the nitro group,
a process which influences the rate of entry of the drug into the susceptible cell and which
is determined by mechanisms involving ferredoxin-linked (or the equivalent) reactions in the cell.


Drugs of the 5-nitro variety include:

  • Metronidazole
  • Tinidazole
  • Nimorazole
  • Dimetridazole
  • Pretomanid
  • Ornidazole
  • Megazol
  • Azanidazole.
  • Drugs based on 2-nitromidazoles include benznidazole.