1. Clinical Overview
A fixed-dose combination (FDC) medication widely used in India for symptomatic relief of common cold, allergic rhinitis, and sinusitis. It combines an antihistamine (Chlorpheniramine), an analgesic-antipyretic (Paracetamol), and a decongestant (Phenylephrine) to provide comprehensive relief from fever, pain, nasal congestion, sneezing, and runny nose.
| Onset | Duration | Bioavailability |
|---|---|---|
| Paracetamol: 30-60 minutes; Phenylephrine: 15-30 minutes; Chlorpheniramine: 30-60 minutes. | Paracetamol: 4-6 hours; Phenylephrine: 4-6 hours; Chlorpheniramine: 4-6 hours. | Chlorpheniramine: ~25-50% (oral); Paracetamol: ~85-98% (oral); Phenylephrine: ~38% (oral, significant first-pass metabolism). |
2. Mechanism of Action
This combination works synergistically. Chlorpheniramine competitively antagonizes histamine at H1 receptors, reducing allergic symptoms. Paracetamol inhibits cyclooxygenase (COX) enzymes, particularly in the CNS, reducing prostaglandin synthesis for analgesia and antipyresis. Phenylephrine is a selective alpha-1 adrenergic agonist causing vasoconstriction in nasal mucosa, reducing edema and congestion.
3. Indications & Uses
- Symptomatic relief of common cold
- Allergic rhinitis (seasonal & perennial)
- Acute sinusitis with congestion
- Influenza (symptomatic relief of fever, headache, body ache, and nasal symptoms)
4. Dosage & Administration
Adult Dosage: One tablet every 4-6 hours. Maximum: 4 tablets in 24 hours.
Administration: Take with or without food. Swallow whole with a glass of water. Do not crush or chew. Can be taken after meals to reduce gastric upset. Maintain adequate hydration.
5. Side Effects
Common side effects may include:
- Drowsiness/Sedation
- Dry mouth
- Dry nose/throat
- Dizziness
- Headache
- Gastrointestinal discomfort
- Mild increase in blood pressure
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Monoamine Oxidase Inhibitors (MAOIs) - Phenelzine, Tranylcypromine | Risk of severe hypertensive crisis due to potentiation of phenylephrine. | Contraindicated |
| Other Sedatives (Alcohol, Benzodiazepines, Opioids) | Additive CNS depression and sedation with chlorpheniramine. | Major |
| Other Paracetamol-containing products | Risk of paracetamol overdose leading to hepatotoxicity. | Major |
| Antihypertensives (Beta-blockers, Alpha-blockers) | Phenylephrine may antagonize hypotensive effect; increased risk of hypertension with non-selective beta-blockers. | Moderate |
| Tricyclic Antidepressants (Amitriptyline, Imipramine) | Additive anticholinergic effects and potential increased pressor response to phenylephrine. | Moderate |
| CNS Stimulants (Amphetamines, Methylphenidate) | Additive sympathomimetic effects, increasing risk of hypertension and tachycardia. | Moderate |
| Warfarin | Chronic high-dose paracetamol may potentiate anticoagulant effect (monitor INR). | Moderate |
7. Patient Counselling
- Do take the exact prescribed dose at recommended intervals.
- Do not take with other paracetamol-containing products (cold remedies, painkillers).
- Do not consume alcohol during treatment.
- Do not drive or operate heavy machinery if feeling drowsy.
- Do inform your doctor if you have high blood pressure, thyroid, prostate, or liver problems.
- Do maintain adequate fluid intake.
8. Toxicology & Storage
Overdose: Chlorpheniramine: CNS depression (sedation, coma) or stimulation (hallucinations, seizures), anticholinergic crisis (flushing, hyperthermia, tachycardia). Paracetamol: Stage 1 (0-24h): Nausea, vomiting, malaise. Stage 2 (24-72h): Right upper quadrant pain, elevated LFTs. Stage 3 (72-96h): Peak hepatotoxicity, jaundice, coagulopathy. Phenylephrine: Severe hypertension, headache, reflex bradycardia, cardiac arrhythmias, pulmonary edema.
Storage: Store below 30°C in a cool, dry place, protected from light and moisture. Keep out of reach of children and pets. Do not use after the expiry date printed on the pack.