Naphazoline is a medicine used as a

decongestant A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter o ...

, and a

vasoconstrictor Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vesse ...

added to

eye drops ''Eye Drops'' is a television program on TechTV that showcased short computer animation movies and clips made using off the shelf 3D animation software. The show claimed to showcase all different types of animation, but only a very small number ...

to relieve red eye. It has a rapid action in reducing swelling when applied to

mucous membranes A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...

. It is a sympathomimetic agent with marked alpha adrenergic activity that acts on alpha-receptors in the

arterioles An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the pr ...

of the

conjunctiva In the anatomy of the eye, the conjunctiva (: conjunctivae) is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with gobl ...

to produce constriction, resulting in decreased congestion. It was patented in 1934 and came into medical use in 1942.

Medical uses

Nasal administration

Nasal

Ophthalmic drug administration

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 (brand names Clear Eyes, and Cleari) narrowing swollen blood vessels ( ophthalmic arteries, and

ophthalmic veins Ophthalmic veins are veins which drain the eye. More specifically, they can refer to: * Superior ophthalmic vein The superior ophthalmic vein is a vein of the orbit that drains venous blood from structures of the upper orbit. It is formed by th ...

) to relieve red eye. Temporary red eye can safely be treated when the cause of the redness is established (e.g.

cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae that is widely accepted as being indigenous to and originating from the continent of Asia. However, the number of species is disputed, with as many as three species be ...

induced conjunctival vasodilation). However, continuous use is not recommended without knowing an underlying condition.

Side effects

A few warnings and contraindications that apply to all naphazoline-containing substances intended for medicinal use are: * Hypersensitivity to naphazoline * Use in infants and children can result in

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

depression, leading to coma and marked reduction in

body temperature Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

* Should be used with caution in patients with severe

cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...

including

cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – above 100 beat ...

and in patients with

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

, especially those with a tendency toward diabetic

ketoacidosis Ketoacidosis is a metabolic state caused by uncontrolled production of ketone bodies that cause a metabolic acidosis. While ketosis refers to any elevation of blood ketones, ketoacidosis is a specific pathologic condition that results in changes i ...

* A possible association with stroke has been suggested.

Nasal administration

* Extended use may cause

rhinitis medicamentosa Rhinitis medicamentosa (or RM, also known as rebound congestion) is a condition of rebound nasal congestion suspected to be brought on by extended use of topical decongestants (e.g., oxymetazoline, phenylephrine, xylometazoline, and naphazoli ...

, a condition of rebound

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 ...

Ophthalmic drug administration

Known side-effect: * Stinging * Discomfort * Irritation * Increased red eyes *

Blurred vision Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressur ...

Mydriasis Mydriasis is the Pupillary dilation, dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, Physical trauma, trauma, or the use of c ...

* Punctate keratitis *

Lacrimation Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of ...

(tears) * Increased

intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated t ...

Contraindications

* Patients taking MAO inhibitors can experience a severe

hypertensive Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk ...

crisis if given a sympathomimetic drug such as naphazoline HCl * Drug interactions can occur with

anaesthetics An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into tw ...

that sensitize the

myocardium Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall o ...

to sympathomimetics (e.g.

cyclopropane Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a triangular ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane ...

halothane Halothane, sold under the brand name Fluothane among others, is a general anaesthetic. It can be used to induce or maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be particularly useful ...

cautiously) * Exercise caution when applying prior to use of

phenylephrine Phenylephrine, sold under the brand names Neosynephrine and Sudafed PE among others, is a medication used as a decongestant for uncomplicated nasal congestion in the form of a nasal spray or oral tablet, to dilate the pupil, to increase bloo ...

Pharmacology

Naphazoline is a mixed α₁- and α₂-adrenergic receptor

agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...

Chemistry

The non-hydrochloride form of Naphazoline has the

molecular formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as paren ...

C₁₄H₁₄N₂ and a

molar mass In chemistry, the molar mass () (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical substance ( element or compound) is defined as the ratio between the mass () and the amount of substance ...

of 210.28 g/mol. The HCl salt form has a molar mass of 246.73 g/mol.

Society and culture

It is an

active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. ...

in several

over-the-counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid pres ...

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 ...

formulations including Clear Eyes, Rohto Cool, Eucool, and Naphcon-A.

Illicit use

The nasal or ophthalmic form of naphazoline has been abused by

heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a morphinan opioid substance synthesized from the Opium, dried latex of the Papaver somniferum, opium poppy; it is mainly used as a recreational drug for its eupho ...

cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

drug addicts. It's used as CNS stimulant and

to enhance primary drug effects.

References

{{Phenethylamines Alpha-1 adrenergic receptor agonists Alpha-2 adrenergic receptor agonists Decongestants Imidazolines 1-Naphthyl compounds Naphthylethylamines Vasoconstrictors Ophthalmology drugs