Аннотация
The histamine is a natural compound derived from histidine and amino acid which act on different histaminic receptors (H1, H2, H3 and H4), each receptor combined with histamine and give the different actions especially H1 and H2 receptors. The action of each depends on the specificity of the receptors, e.g., the compounds which act on H1 receptor are similar to each other but different than the compounds which act on H2 receptor (due to the difference between two receptors from the area and stereo of the receptors).