Antazoline is a 1st generation

antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides ...

with

anticholinergic Anticholinergics (anticholinergic agents) are substances that block the action of the acetylcholine (ACh) neurotransmitter at synapses in the central nervous system, central and peripheral nervous system. These agents inhibit the parasympatheti ...

properties used to relieve

nasal congestion Nasal congestion is the partial or complete blockage of nasal passages, leading to impaired nasal breathing, usually due to membranes lining the nose becoming swollen from inflammation of blood vessels. Background In about 85% of cases, nasal ...

and in

eye drop Eye drops or eyedrops are liquid drops applied directly to the surface of the eye usually in small amounts such as a single drop or a few drops. Eye drops usually contain saline to match the salinity of the eye. Drops containing only saline ...

s, usually in combination with

naphazoline Naphazoline is a medicine used as a decongestant, and a vasoconstrictor added to eye drops to relieve red eye. It has a rapid action in reducing swelling when applied to mucous membranes. It is a sympathomimetic agent with marked alpha adrener ...

, to relieve the symptoms of

allergic Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...

conjunctivitis Conjunctivitis, also known as pink eye or Madras eye, is inflammation of the conjunctiva, the thin, clear layer that covers the white surface of the eye and the inner eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness ...

. To treat allergic conjunctivitis, antazoline can be combined in a solution with

tetryzoline Tetryzoline (INN), also known as tetrahydrozoline, is a drug used in some over-the-counter eye drops and nasal sprays. Tetryzoline was patented in 1954, and came into medical use in 1959. Side effects Tetryzoline eye drops may cause blurred vis ...

. The drug is a

Histamine H1 receptor The H1 receptor is a histamine receptor belonging to the family of rhodopsin-like G-protein-coupled receptors. This receptor is activated by the biogenic amine histamine. It is expressed in smooth muscles, on vascular endothelial cells, in ...

antagonist: selectively binding to but not activating the receptor, thereby blocking the actions of endogenous

histamine Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ...

and subsequently leading to the temporary relief of the negative symptoms brought on by histamine. A large study on people 65 years old or older linked the development of

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

and other forms of dementia to the "higher cumulative" use of first-generation antihistamines, due to their

properties.

References

H1 receptor antagonists Imidazolines {{respiratory-system-drug-stub