1. Clinical Overview
A fixed-dose combination (FDC) medication primarily indicated for the symptomatic relief of allergic rhinitis and the common cold. It combines a second-generation, non-sedating antihistamine (Fexofenadine), a nasal decongestant (Phenylephrine), and an analgesic-antipyretic (Paracetamol). This combination addresses the core symptoms of rhinorrhea, sneezing, nasal congestion, headache, body ache, and fever associated with upper respiratory allergies and infections. The FDC is widely used in the Indian market for its comprehensive symptom relief and favorable safety profile.
| Onset | Duration | Bioavailability |
|---|---|---|
| Fexofenadine: 1-3 hours; Phenylephrine: 15-30 minutes; Paracetamol: 30-60 minutes. | Fexofenadine: 24 hours; Phenylephrine: 4-6 hours; Paracetamol: 4-6 hours. | Fexofenadine: ~30-40%; Phenylephrine: ~38% (oral); Paracetamol: ~85-98%. |
2. Mechanism of Action
The combination exerts a multi-targeted effect. Fexofenadine competitively and selectively inhibits peripheral H1-histamine receptors, blocking the action of histamine released during allergic reactions. Phenylephrine is a selective alpha-1 adrenergic receptor agonist that causes vasoconstriction of dilated arterioles in the nasal mucosa, reducing tissue hyperemia, edema, and nasal congestion. Paracetamol (Acetaminophen) acts centrally by inhibiting the cyclooxygenase (COX) pathways, particularly the COX-2 variant, and modulates the endogenous cannabinoid system, leading to analgesic and antipyretic effects with minimal peripheral anti-inflammatory activity.
3. Indications & Uses
- Symptomatic relief of Allergic Rhinitis (Seasonal & Perennial)
- Symptomatic relief of Common Cold
4. Dosage & Administration
Adult Dosage: One tablet twice daily. The interval between two doses should not be less than 6 hours.
Administration: Administer orally with a full glass of water. Can be taken with or without food, but taking with food may reduce potential gastric upset from paracetamol. Avoid taking with fruit juices (apple, orange, grapefruit) as they can significantly reduce fexofenadine absorption. Do not crush or chew.
5. Side Effects
Common side effects may include:
- Headache
- Drowsiness (rare with fexofenadine, but possible)
- Nausea
- Dry mouth
- Dizziness
- Insomnia (due to phenylephrine)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Monoamine Oxidase Inhibitors (e.g., Phenelzine, Selegiline) | Risk of severe hypertensive crisis due to potentiation of phenylephrine's vasopressor effects. | Contraindicated |
| Beta-blockers (e.g., Propranolol) | Unopposed alpha-adrenergic activity from phenylephrine can lead to severe hypertension and bradycardia. | Major |
| Other sympathomimetics (e.g., Pseudoephedrine, in cough syrups) | Additive vasopressor and CNS stimulant effects, increasing risk of hypertension and tachycardia. | Major |
| Antihypertensives (e.g., ACE inhibitors, Diuretics) | Phenylephrine may antagonize the blood pressure-lowering effect. | Moderate |
| Alcohol | Increased risk of hepatotoxicity with paracetamol; enhanced CNS depression with fexofenadine (though minimal). | Major |
| Drugs inducing liver enzymes (e.g., Rifampicin, Carbamazepine, Phenytoin) | Increased metabolism of paracetamol to toxic metabolite (NAPQI), raising hepatotoxicity risk. | Major |
| Warfarin | Paracetamol may potentiate anticoagulant effect, increasing INR and bleeding risk, especially with high doses (>2g/day). | Moderate |
| Antacids containing Aluminium & Magnesium | Reduce absorption of fexofenadine. Administer at least 2 hours apart. | Moderate |
| Erythromycin, Ketoconazole | May increase plasma concentration of fexofenadine via P-glycoprotein inhibition, potentially increasing side effects. | Moderate |
7. Patient Counselling
- DO take the tablet with water, not with fruit juice.
- DO inform your doctor about all other medicines you are taking, including OTC products.
- DO not exceed the recommended dose or frequency.
- DO not take for more than 5-7 days for fever or 10 days for pain without consulting a doctor.
- DO not use to make a child sleepy.
- DO not take with other paracetamol-containing products (e.g., cold syrups, pain relievers).
8. Toxicology & Storage
Overdose: Manifestations are component-specific. Fexofenadine: Drowsiness, dizziness, dry mouth (generally low toxicity). Phenylephrine: Severe hypertension, headache, palpitations, tachycardia, arrhythmias, nervousness, vomiting. Paracetamol: Stage 1 (0-24h): Nausea, vomiting, anorexia, malaise. Stage 2 (24-72h): Right upper quadrant pain, elevated LFTs. Stage 3 (72-96h): Peak hepatotoxicity, jaundice, coagulopathy, encephalopathy, potentially fatal hepatic necrosis. Stage 4 (4 days-2 weeks): Recovery.
Storage: Store below 30°C, in a cool, dry place. Protect from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.