Chlorpheniramine

BRAND NAMES:

Aller-Chlor-It contains the active ingredients of chlorpheniramine maleate. It is available in the form of tablets.

Chlor-Amine- It contains the active ingredients of chlorpheniramine maleate. It is available in the form of tablets.

Chlor-triton- contains the active ingredients of chlorpheniramine maleate. It is available in the form of tablets to treat allergic symptoms.

Chlor-tricolon- It contains the active ingredients of chlorpheniramine maleate.

It is available in the form of tablets used to treat fast allergic conditions.

MECHANISM OF ACTION:

Chlorpheniramine binds to histamine H1 receptors. This inhibits the activity of endogenous histamine, providing brief respite from histamine-induced unpleasant sensations.

PHARMACOKINETICS:

Absorption: When taken orally, chlorpheniramine is readily absorbed from the gastrointestinal tract. 30 minutes is when the effects start, they peak in 1 to 2 hours, and they last for 4 to 6 hours. The estimated half-life of plasma is between 12 and 15 hours.

Distribution: In adults, the apparent steady-state volume of distribution for chlorpheniramine is approximately 3 litres per kilogramme, while in children, it is approximately 3.8 L/kg.

Metabolism: Chlorpheniramine is metabolized extensively in the gastrointestinal mucosa and liver during absorption and first pass.

Excretion: Chlorpheniramine and its metabolites are excreted almost exclusively through the kidneys.

PHARMACODYNAMICS:

Chlorpheniramine is a histamine H1 antagonist 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 from sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies.

DOSAGE AND ADMINISTRATION:

Chlorpheniramine is available in the following dosage forms

• Oral syrup-2mg/5ml
• Oral tablet-4mg
• Extended-release oral tablets- 12 mg
• Syrup-2mg/ml

You can take chlorpheniramine with or without food. Children may find it easier to take liquid chlorpheniramine than tablets. 

Tablets/syrup: 4 mg taken orally every 4–6 hours, up to a daily maximum of 24 mg. 
Tablets with extended release: 8 mg every 8–12 hours or 12 mg every 12 hours, with a daily maximum of 24 mg 
Extended-release capsules: 12 mg once daily, up to a daily maximum of 24 mg 
Sustained release capsules: 8–12 mg taken orally every 8–12 hours, up to a daily maximum of 16–24 mg.

CONTRAINDICATIONS:

Hypersensitivity to chlorpheniramine or any of the formulation's components, narrow-angle glaucoma, bladder neck obstruction, symptomatic prostate hypertrophy, acute asthmatic attacks, stenosing peptic ulcer, H. pylori duodenal obstruction.

DRUG INTERACTIONS:

Some products that may interact with this drug are 

• Muscle relaxants-Carisoprodol, Cyclobenzaprine
• Anti-histamines- Cetirizine, Diphenhydramine.
• Cough – relievers- Codeine, hydrocodone
• Opioid- Codeine, hydrocodone

SIDE EFFECTS:

Side effects of chlorpheniramine include

• Fast or uneven heart rate
• Mood changes
• Tremor, seizure
• Easy bruising or bleeding unusual weakness
• Little or no urinating.

Common side effects of chlorpheniramine may include 

• Dizziness, drowsiness
• Dry mouth, nose or throat
• Constipation
• Blurred 
• Feeling nervous or restless

OVERDOSE:

Symptoms of overdose include

• Large pupils
• Flushing
• Fever
• Hallucinations,
• Weakness
• Shaking
• Muscle twitching
• Loss of consciousness
• Seizures.

TOXICITY:

According to previous reports in the relevant literature, most overdoses of chlorpheniramine are 200 mg to 240 mg. The oral dose in this case was 4000mg which is the highest reported dose for acute poisoning with chlorpheniramine.

STORAGE:

Chlorpheniramine should be stored in a firmly sealed container, stored at room temperature from 20°-25°C (68°-77 °F)