Dexchlorpheniramine

What is Dexchlorpheniramine?

Dexchlorpheniramine is a Pharmacy Only Medicine widely used to relieve symptoms of seasonal allergies, hay fever, and skin conditions like hives. It is frequently formulated as a standalone tablet or syrup, and is sometimes included in multi-ingredient cough and cold preparations to help dry up excessive nasal secretions.

As a first-generation antihistamine, it is the dextrorotatory isomer of chlorpheniramine. This specific chemical synthesis makes it approximately twice as potent as standard racemic chlorpheniramine, allowing for effective allergy symptom relief at lower administered dosages.

Generic Names:

• Dexchlorpheniramine maleate: The standard generic name used globally for this active isomer formulation.

Global Brand Names:

Dexchlorpheniramine is available under several brand and generic names in Hong Kong.

• Polaramine (寶立敏): The primary brand reference in Hong Kong, commonly available as oral tablets and syrup.
• Dexphen: A common generic version manufactured locally in Hong Kong.
• Dexamine: A generic preparation frequently dispensed directly in local clinical settings.

These names all refer to the same medication. It's important to note that while the active ingredient is the same, different countries may have different regulations and available medication formulations.

What is Dexchlorpheniramine used for?

Dexchlorpheniramine is used to relieve:

• Seasonal and perennial allergic rhinitis (hay fever).
• Allergic conjunctivitis (eye allergies).
• Urticaria (hives) and angioedema.
• Itching associated with insect bites or plant rashes.

How do you use Dexchlorpheniramine?

Availability:

• Oral tablets
• Extended-release tablets (Repetabs)
• Oral syrup

Dosage Information:

• Adults and children over 12: 2 mg every 4 to 6 hours, up to a maximum of 12 mg daily.
• Children 6 to 11 years: 1 mg every 4 to 6 hours, up to a maximum of 6 mg daily.
• Children 2 to 5 years: 0.5 mg every 4 to 6 hours, up to a maximum of 3 mg daily.
• Elderly: Start at a lower dose due to increased sensitivity to sedative effects.

Suitability:

• Adults: Yes.
• Elderly: Yes, with caution due to sedation sensitivity.
• Children over 2 years: Yes.
• Newborns and premature infants: No.

Who cannot take Dexchlorpheniramine?

Allergies and unsuitability:

• Rare, but possible allergic reactions to antihistamines.

Conditions where the drug should not be used:

• Active therapy with Monoamine Oxidase Inhibitors (MAOIs)
• Narrow-angle glaucoma
• Symptomatic prostatic hypertrophy
• Bladder neck obstruction
• Stenosing peptic ulcer

The most common side effect of dexchlorpheniramine is drowsiness or sedation, which can vary from mild sleepiness to deep sleep. Other frequently reported reactions include a dry mouth, nose, and throat, thickening of bronchial secretions, dizziness, and mild stomach upset. Because it is a first-generation antihistamine, these central nervous system and anticholinergic effects are prominent.

Severe adverse reactions are rare but can include allergic responses like rash or anaphylaxis, urinary retention, blurred vision, and heart palpitations. In children, a paradoxical excitation may occur, causing unusual restlessness, insomnia, and tremors instead of sedation. If any severe or unusual symptoms arise, medical attention should be sought promptly.

• Do not drive or operate heavy machinery until you know how this medication affects you, due to the risk of severe drowsiness.
• Avoid alcohol and central nervous system depressants to reduce the risk of excessive sedation and motor impairment.
• Do not take this medication if you have used Monoamine Oxidase Inhibitors (MAOIs) within the past 14 days to prevent severe hypertension and anticholinergic crisis.
• Check with a doctor before use if you have an enlarged prostate or glaucoma, as the medication may worsen these conditions.

Storage information:

• Store at room temperature between 15°C and 30°C.
• Keep in a cool, dry place away from moisture and direct light.
• Keep out of reach of children.

Handling instructions:

• Use the measuring device that comes with the liquid syrup for the correct dose, rather than a household spoon.
• Swallow extended-release tablets whole; do not crush or chew them.
• Take with food or milk if the medication causes mild stomach upset.

Where is Dexchlorpheniramine available in Hong Kong?

In Hong Kong, Dexchlorpheniramine is classified as a Pharmacy Only Medicine. While a doctor's prescription is not required, it must be purchased at a registered pharmacy under the direct supervision of a registered pharmacist.

You can legally obtain this medication at registered dispensaries displaying the "Rx" logo, as well as at the pharmacy counters of general chain drug stores like Mannings and Watsons. It is also routinely dispensed directly by doctors in local clinical settings.