Histamine dihydrochloride
[CAS# 56-92-8]

Identification

• Classification: Biochemical >> Inhibitor >> Neuronal signaling >> Histamine receptor agonist
• Name: Histamine dihydrochloride
• Synonyms: 2-(4-Imidazolyl)ethylamine dihydrochloride; 2-(1H-Imidazol-4-yl)ethylamine dihydrochloride
• Molecular Formula: C₅H₉N₃.₂HCl;C₅H₁₁Cl₂N₃
• Molecular Weight: 184.07
• CAS Registry Number: 56-92-8
• EC Number: 200-298-4
• SMILES: C1=C(NC=N1)CCN.Cl.Cl

Properties

• Solubility: soluble 100 mM (water), 100mM (DMSO) (Expl.)
• Melting point: 249-252 °C (Expl.)

Safety Data

• Hazard Symbols: GHS07;GHS08 Danger
• Risk Statements: H315-H317-H319-H334-H335
• Safety Statements: P233-P260-P261-P264-P264+P265-P271-P272-P280-P284-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P333+P317-P337+P317-P342+P316-P362+P364-P403-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Skin sensitization	Skin Sens.	1	H317
Respiratory sensitization	Resp. Sens.	1	H334
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319
Skin sensitization	Skin Sens.	1B	H317
Specific target organ toxicity - single exposure	STOT SE	1	H370
Respiratory sensitization	Resp. Sens.	1B	H334

Discovery and Applications

Histamine dihydrochloride is a chemical compound that consists of histamine, a biogenic amine, combined with two molecules of hydrochloric acid. It plays a significant role in various physiological processes, particularly in the immune response and regulation of gastric acid secretion. As a key mediator in allergic reactions, histamine is involved in the inflammatory response and the dilation of blood vessels. Histamine dihydrochloride is the dihydrochloride salt of histamine and is used in both research and clinical settings, especially for its role in pharmacology and diagnostic applications.

The discovery of histamine can be traced back to the early 20th century, when scientists first identified its presence in tissues and its role in various biological functions. In 1910, the biochemist Sir Henry Dale successfully isolated histamine and demonstrated its importance as a neurotransmitter and mediator of allergic responses. Subsequent research led to the identification of its receptors and their role in physiological processes such as smooth muscle contraction, increased blood flow, and gastric acid secretion. The dihydrochloride salt form of histamine, specifically histamine dihydrochloride, was developed for its stability and ease of handling in laboratory and clinical settings.

One of the primary applications of histamine dihydrochloride is in clinical and diagnostic testing. It is used in skin tests for diagnosing allergies, as histamine is known to trigger an allergic reaction. The compound is injected into the skin to induce a local inflammatory response, helping clinicians identify allergens by comparing the reaction to known allergens. This technique is particularly useful for testing for sensitivity to various environmental factors, such as pollen, dust, or animal dander. Histamine dihydrochloride is also used in bronchial provocation tests to evaluate bronchial hyperreactivity in asthma patients, as it causes bronchoconstriction, aiding in the assessment of asthma severity and response to treatment.

In addition to diagnostic applications, histamine dihydrochloride is important in the field of pharmacology. It serves as a standard in research studies investigating histamine receptor antagonists, or antihistamines. These compounds are widely used for treating allergic reactions, hay fever, and rhinitis by blocking the effects of histamine on its receptors, thereby reducing symptoms like itching, swelling, and nasal congestion. Histamine dihydrochloride is also employed in studies exploring the role of histamine in central nervous system function, where it acts as a neurotransmitter and is involved in regulating wakefulness, arousal, and appetite.

Another significant application of histamine dihydrochloride is in research on gastric acid secretion. Histamine is a potent stimulator of gastric acid production in the stomach, and histamine dihydrochloride is used in pharmacological studies to evaluate the effects of different substances on gastric acid secretion. This is particularly important in the development of drugs aimed at treating conditions like peptic ulcers, gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome, where excessive gastric acid production is a contributing factor.

Furthermore, histamine dihydrochloride is used in various experimental models to study its effects on blood pressure, heart rate, and smooth muscle tone. Its ability to induce vasodilation and modulate vascular permeability makes it a valuable tool in cardiovascular research, as it can help investigate mechanisms related to allergic responses, inflammation, and anaphylaxis.

In conclusion, histamine dihydrochloride is an important chemical compound with significant applications in clinical diagnostics, pharmacology, and biomedical research. Its role in allergic reactions, gastric acid secretion, and neurotransmission has made it an essential substance in various fields, from allergy testing to drug development. As our understanding of histamine’s role in human health continues to evolve, histamine dihydrochloride will likely remain a valuable tool in both clinical and laboratory settings.

References

2024. Bioactive Amines in Conventional and Non-Conventional Edible Plants from Brazil: Health Benefits and Concerns. Food Biophysics, 19.
DOI: 10.1007/s11483-024-09864-4

1979. Effect of histamine and acetylcholine on hypophysial stalk plasma dopamine and peripheral plasma prolactin levels. Life Sciences, 24(22).
DOI: 10.1016/0024-3205(79)90079-1

1979. Relaxant action of histamine on rabbit trachea: possible existence of third histamine receptor subtype. Research communications in chemical pathology and pharmacology, 23(2).
URL: pubmed.ncbi.nlm.nih.gov/461948