Histacin 100ml Syrup contains Chlorpheniramine Maleate BP 2 mg per 5 ml. It is manufactured by Jayson Pharmaceuticals Limited in Bangladesh.  

Indications:

Histacin Syrup is a sedating antihistamine used for the symptomatic relief of various allergic conditions, including:  

• Allergic rhinitis (hay fever and perennial allergic rhinitis)  
• Allergic conjunctivitis
• Urticaria (hives)  
• Angioedema (swelling beneath the skin)  
• Pruritic skin disorders (itchy skin conditions)  
• As an adjunct in the emergency treatment of anaphylactic reactions.  
• Vasomotor rhinitis
• Cough and common cold symptoms  
• Motion sickness

Pharmacology:

Chlorpheniramine Maleate is an alkylamine antihistamine. It works by competitively blocking histamine H1-receptors, thereby counteracting the effects of histamine which are released during allergic reactions. It also has weak antimuscarinic (anticholinergic), moderate antiserotonin, and local anesthetic actions. It generally causes less sedation compared to some other first-generation antihistamines like promethazine.  

Dosage and Administration (Oral):

Histacin Syrup can be taken by adults and children. Always follow the dosage instructions given by your physician.  

• Adults and Children (≥12 years): 10-20 ml (2-4 teaspoonfuls) three times daily. Max: 24 mg (60 ml) daily.  
• Children 6-12 years: 10 ml (2 teaspoonfuls) three to four times daily. Max: 12 mg (30 ml) daily.  
• Children 2-5 years: 5 ml (1 teaspoonful) three to four times daily. Max: 6 mg (15 ml) daily.  
• Children 1-2 years: 5 ml (1 teaspoonful) twice daily.  
• Infants (below 1 year): 2.5 ml (½ teaspoonful) once daily. (Note: Use in infants below 1 year is generally not recommended without strict medical advice).  

Contraindications:

• Known allergy to Chlorpheniramine Maleate or any component of the syrup.  
• Newborn or premature infants.  
• Not recommended for use during pregnancy, especially the first trimester, or lactation.  

Side Effects:

Chlorpheniramine is generally well-tolerated, but common side effects include:  

• Drowsiness (most common, especially with higher doses)  
• Dizziness  
• Muscular weakness  
• Gastrointestinal upset (nausea, vomiting, abdominal pain, diarrhea or constipation)  
• Dry mouth, nose, and throat  
• Blurred vision  
• Headache  
• Paradoxical excitation (restlessness, insomnia), especially in children.  

Precautions and Warnings:

• Sedation: May cause drowsiness. Patients should be cautioned against driving or operating hazardous machinery until their response to the drug is known.  
• Alcohol: Avoid alcohol consumption as it can increase drowsiness.  
• Underlying conditions: Use with caution in patients with glaucoma, prostatic hypertrophy (enlarged prostate), epilepsy, or hepatic (liver) disease.  
• Children: Children, especially young ones, may be more susceptible to the side effects, including paradoxical excitement.  
• Elderly: Elderly patients may be more prone to side effects like drowsiness and confusion.  

Pregnancy and Lactation:

• Pregnancy: The safety of chlorpheniramine in pregnancy has not been definitively established. It is generally not recommended during pregnancy, especially in the first trimester.  
• Lactation: The drug is excreted in small amounts in breast milk. Mothers taking the drug should generally not breastfeed.  

Drug Interactions:

• CNS depressants: May enhance the sedative effects of other CNS depressants (e.g., alcohol, hypnotics, sedatives, tranquilizers, opioid analgesics).  
• MAO inhibitors (MAOIs): May prolong and intensify the anticholinergic effects of antihistamines, including chlorpheniramine. Avoid concurrent use.  
• Anticholinergic drugs: Concurrent use may lead to increased anticholinergic side effects (e.g., dry mouth, urinary retention).  

Storage Conditions:

Store in a cool (below 25°C) and dry place, protected from light. Keep out of the reach of children.  

Note: This information is for general knowledge and informational purposes only and does not substitute professional medical advice. Always consult your doctor or pharmacist for specific instructions and guidance regarding your medication.