Nazol (micro)

Nazol (micro) Uses, Dosage, Side Effects, Food Interaction and all others data.

Chlorpheniramine is an alkylamine antihistamine. It is one of the most potent H1 blocking agents and is generally effective in relatively low doses. Chlorpheniramine is not so prone to produce drowsiness, readily absorbed from the gastro-intestinal tract, metabolised in the liver and excreted usually mainly as metabolised in the urine.

In allergic reactions an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H1-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Chlorpheniramine, is a histamine H1 antagonist (or more correctly, an inverse histamine agonist) of the alkylamine class. It competes with histamine for the normal H1-receptor sites on effector cells of the gastrointestinal tract, blood vessels and respiratory tract. It provides effective, temporary relief of sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies.

Naphazoline is a rapid acting imidazoline sympathomimetic vasoconstrictor of ocular or nasal artierioles. It acts to decrease congestion and is found in many over the counter (OTC) eye drops and nasal preparations.

Naphazoline was first developed in 1942 as a nasal formulation for congestion.

Naphazoline is a sympathomimetic alpha adrenergic agonist that acts to vasoconstrict nasal or ocular arterioles, resulting in reduced congestion at the site of administration.

Trade Name Nazol (micro)
Generic Chlorpheniramine + Naphazoline
Type Eye Drops
Therapeutic Class
Manufacturer Micro Labs
Available Country India
Last Updated: September 19, 2023 at 7:00 am
Nazol (micro)
Nazol (micro)

Uses

Indicated mainly in allergic conditions including urticaria, sensitivity reactions, angioneurotic oedema, seasonal hay fever, vasomotor rhinitis, cough, common cold, motion sickness.

Naphazoline is a sympathomimetic vasoconstrictor used for the symptomatic relief of redness and itching of the eye, and nasal congestion.

Naphazoline is indicated for use as OTC eyedrops for ocular vasoconstriction or as a nasal preparation for nasal congestion.

Nazol (micro) is also used to associated treatment for these conditions: Allergic Contact Dermatitis, Allergic Reaction, Allergic Rhinitis (AR), Allergic cough, Allergies, Allergies caused by Serum, Allergy to House Dust, Allergy to vaccine, Angioneurotic Edema, Asthma, Bronchial Asthma, Bronchitis, Common Cold, Conjunctival congestion, Conjunctivitis, Conjunctivitis allergic, Cough, Cough caused by Common Cold, Coughing caused by Flu caused by Influenza, Drug Allergy, Eye allergy, Fever, Flu caused by Influenza, Food Allergy, Headache, Headache caused by Allergies, Itching of the nose, Itching of the throat, Migraine, Nasal Congestion, Nasal Congestion caused by Common Cold, Pollen Allergy, Productive cough, Pruritus, Rash, Rhinorrhoea, Seasonal Allergic Conjunctivitis, Sinus Congestion, Sinusitis, Sneezing, Transfusion Reactions, Upper Respiratory Tract Infection, Upper respiratory tract hypersensitivity reaction, site unspecified, Urticaria, Vasomotor Rhinitis, Acute Rhinitis, Allergic purpura, Conjunctival hyperemia, Dry cough, Excess mucus or phlegm, Itchy throat, Mild bacterial upper respiratory tract infections, Ocular hyperemia, Throat inflammation, Upper airway congestion, Upper respiratory symptoms, Watery eyes, Watery itchy eyes, Airway secretion clearance therapyBacterial Conjunctivitis, Blepharoconjunctivitis, Conjunctivitis, Conjunctivitis allergic, Dacryocystitis, Dacryostenosis, Dermatitis, Eczematous of the Eyelid, Eye Pain, Eye redness, Iritis, Lacrimation, Nasal Allergies, Nasal Congestion, Noninfective conjunctivitis, Otitis Media (OM), Photophobia, Foreign body sensation in eye, Ocular bacterial infections, Ocular vasoconstriction

How Nazol (micro) works

Chlorpheniramine binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.

Naphazoline is a vasoconstrictor that functions by stimulating alpha adrenergic receptors in arterioles leading to decreased congestion at the site of administration.

Naphazoline causes the release of norepinephrine in sympathetic nerves. Norepinephrine binds to alpha adrenergic receptors and causes vasoconstriction. Naphazoline is also a mild beta adrenergic receptor agonist, which can cause rebound vasodilation after the alpha adrenergic stimulation has ended. Naphazoline's release of norepinephrine also triggers a negative feedback loop which decreases production of norepinephrine, which can lead to rhinitis medicamentosa after long term use when naphazoline is stopped.

Dosage

Nazol (micro) dosage

Adults: 4 mg 3-4 times daily.

Children:

  • Up to 1( one) year: 1 mg twice daily
  • 1-5 years: 1 mg 3-4 times daily
  • 6-12 years: 2 mg 3-4 times daily or as directed by the physician

Side Effects

Drowsiness, dizziness, headache, psychomotor impairment, urinary retention, dry mouth, blurred vision and gastro intestinal disturbances, paradoxical stimulation may rarely occur, especially in high dosage or in children.

Toxicity

Oral LD50 (rat): 306 mg/kg; Oral LD50 (mice): 130 mg/kg; Oral LD50 (guinea pig): 198 mg/kg [Registry of Toxic Effects of Chemical Substances. Ed. D. Sweet, US Dept. of Health & Human Services: Cincinatti, 2010.] Also a mild reproductive toxin to women of childbearing age.

In high doses or when ingested, naphazoline can lead to central nervous system depression (which can progress to coma and death), hypothermia, bradycardia, and death. This effect is especially pronounced in children under 6 years.

Long term use of naphazoline can lead to rhinitis medicamentosa once naphazoline is stopped. This condition is a result of norepinephrine release by naphazoline triggering a negative feedback loop.

Safety and effectiveness in children under 12 has not been established. Studies in elderly patients have yet to be performed. Risk in pregnancy, breast feeding, and on overall fertility have not been established, though pregnant and breast feeding patients should consider the risk and benefit before starting naphazoline treatment.

Precaution

Chlorpheniramine may produce mild sedation and it is advised that patients under continuous treatment should avoid operating machinery. Not recommended during pregnancy & lactation.

Interaction

Alcohol, CNS depressants, anticholinergic drugs, MAOIs.

Volume of Distribution

Distribution data for naphazoline are scarce but imidazoline compounds are distributed throughout the body, and can cross the blood-brain barrier.

Elimination Route

Well absorbed in the gastrointestinal tract.

Absorption data for naphazoline are scarce but imidazoline compounds in general are weakly basic and lipophilic, with high bioavailability from the gastrointestinal tract.

Half Life

21-27 hours

Half life has not been determined but effects last for 4 to 8 hours. Other imidazoline compounds have half lives varying from 2 to 12 hours.

Clearance

Clearance data for naphazoline is unavailable.

Elimination Route

Imidazoline compounds undergo some hepatic metabolism but a large fraction of the dose may be excreted unchanged in the urine. Urinary excretion is higher with more acidic urine.

Pregnancy & Breastfeeding use

Pregnancy Category B. Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Contraindication

There is no definite contraindication to therapy. It should be used with caution in epilepsy, prostatic hypertrophy, glaucoma and hepatic disease. The ability to drive or operate machinery may be impaired.

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