NOSTAMINE EYE/NOSE DROPS

Indications

• Allergic rhinitis (hay fever)
• Urticaria (hives)
• Allergic conjunctivitis
• Common cold symptoms

Dosage

Children: For children aged 6-12 years, the dose is typically 2 mg every 4 to 6 hours, not exceeding 12 mg per day. For children under

Adults: The usual adult dose for chlorpheniramine is 4 mg every 4 to 6 hours, not to exceed 24 mg per day.

Mechanism of action

Chlorpheniramine binds to the histamine H1 receptor, preventing endogenous histamine from exerting its effects. This leads to temporary relief from symptoms such as sneezing, pruritus, and increased vascular permeability associated with allergic reactions. The drug competes with histamine for H1-receptor sites on effector cells, thus antagonizing most of the pharmacological effects of histamine, including its actions on smooth muscle and vascular permeability.

Pharmacodynamics

In allergic reactions, allergens trigger the degranulation of mast cells and basophils, leading to the release of histamine. Chlorpheniramine, as an H1 antagonist, competes for receptor binding, effectively blocking histamine-induced effects, such as itching, vasodilation, and bronchoconstriction. This results in relief from symptoms like sneezing, watery eyes, and nasal discharge.

Pharmacokinetics

Chlorpheniramine is well absorbed from the gastrointestinal tract. It undergoes hepatic metabolism and its effects can last for several hours. The onset of action is typically observed within 1 to 2 hours following oral administration, with peak effects occurring around 2 to 6 hours. The drug is eliminated primarily through urine, with a half-life ranging from 12 to 15 hours, though this can vary based on individual factors.

Contra-indications

• Hypersensitivity to chlorpheniramine or any component of the formulation
• Acute asthma attacks
• Severe hypertension
• Narrow-angle glaucoma
• Prostatic hypertrophy

Adverse effects

• Drowsiness
• Dizziness
• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Confusion
• Headache

Interactions

• Alcohol
• CNS depressants
• MAO inhibitors
• Anticholinergic agents
• Beta-blockers

Precautions

• Use with caution in patients with cardiovascular disease
• Caution in patients with liver or kidney impairment
• Avoid in elderly patients due to increased risk of sedation and anticholinergic effects
• May impair the ability to drive or operate machinery

Pregnancy

Chlorpheniramine should be used in pregnancy only if clearly needed. Consult medical professionals for guidance.

Breast-feeding

Chlorpheniramine is excreted in breast milk. Caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Tablets
• Syrup
• Oral suspension

Indications

• Nasal congestion due to allergic rhinitis
• Nasal congestion due to upper respiratory infections
• Redness of the eyes due to minor irritants or allergens
• Ocular redness associated with eye fatigue or exposure to irritants

Dosage

Children: Refer to product labeling for specific formulations and dosing instructions.

Adults: Refer to product labeling for specific formulations and dosing instructions.

Mechanism of action

Naphazoline acts as an agonist at alpha-adrenergic receptors, particularly alpha-1 adrenergic receptors. This activation leads to vasoconstriction of the blood vessels, reducing blood flow to the affected area and resulting in decreased nasal congestion and ocular redness.

Pharmacodynamics

The pharmacodynamic effects of naphazoline include rapid onset of action, typically within minutes, and prolonged vasoconstriction that can last for several hours. Its ability to reduce mucosal edema makes it effective for symptomatic relief in conditions such as allergic rhinitis and conjunctival hyperemia. However, prolonged use can lead to rebound congestion or tolerance.

Pharmacokinetics

Naphazoline is absorbed locally at the site of application, with systemic absorption being minimal when used as directed. The onset of action is rapid, with peak effects observed shortly after administration. The half-life of naphazoline can vary, but its effects typically last for a few hours. Metabolism occurs primarily in the liver, and elimination is mainly through urine.

Contra-indications

• Hypersensitivity to naphazoline or any component of the formulation
• Concurrent use of monoamine oxidase inhibitors (MAOIs)
• Severe hypertension or cardiovascular disease

Adverse effects

• Local irritation or burning sensation in the eyes
• Pupil dilation (mydriasis)
• Increased intraocular pressure
• Systemic absorption leading to hypertension
• Reflex bradycardia
• Dryness of mucous membranes
• Nausea or vomiting

Interactions

• Monoamine oxidase inhibitors (MAOIs) may enhance the pressor effects of naphazoline
• Other sympathomimetic agents may have additive effects on blood pressure

Precautions

• Use with caution in patients with diabetes, hyperthyroidism, or prostate hypertrophy
• Prolonged use may lead to rebound congestion or dependence
• Should not be used in children under the age of 6 years without medical advice

Pregnancy

Naphazoline should only be used in pregnancy if the potential benefit justifies the potential risk to the fetus. Limited data is available on its safety during pregnancy.

Breast-feeding

Naphazoline is excreted in breast milk; caution is advised if it is used during breastfeeding.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Ophthalmic solution (0.03% and 0.1%)
• Nasal spray (0.05% and 0.1%)

Mechanism of action

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. Antihistamines used in the treatment of allergy act by competing with histamine for H1-receptor sites on effector cells. They thereby prevent, but do not reverse, responses mediated by histamine alone. Antihistamines antagonize, in varying degrees, most of the pharmacological effects of histamine, including urticaria and pruritus. Also, the anticholinergic actions of most antihistamines provide a drying effect on the nasal mucosa. /Antihistamines/ H1 antagonists inhibit most responses of smooth muscle to histamine. Antagonism of the constrictor action of histamine on respiratory smooth muscle is easily shown in vivo and in vitro. /Histamine Antagonists: H1 Antagonists/ H1 antagonists strongly block the action of histamine that results in increased permeability and formation of edema and wheal. /Histamine Antagonists: H1 Antagonists/ Within the vascular tree, the H1 antagonists inhibit both the vasoconstrictor effects of histamine and, to a degree, the more rapid vasodilator effects that are mediated by H1 receptors on endothelial cells. Residual vasodilatation reflects the involvement of H2 receptors on smooth muscle and can be suppressed only by the concurrent administration of an H2 antagonist. Effects of the histamine antagonists on histamine induced changes in systemic blood pressure parallel these vascular effects. /Histamine Antagonists: H1 Antagonists/ Many of the H1 antagonists tend to inhibit responses to acetylcholine that are mediated by muscarinic receptors. These atropine like actions are sufficiently prominent in some of the drugs to be manifest during clinical usage ... . /Histamine Antagonists: H1 Antagonists/

Pharmacodynamics

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.