Fexo (Fexofenadine): A Non-Sedating Antihistamine for Allergic Relief

Fexo contains Fexofenadine Hydrochloride, a potent and selective H1-histamine receptor inverse agonist. It is classified as a non-sedating antihistamine and is primarily indicated for the symptomatic relief of seasonal and perennial allergic rhinitis, as well as chronic idiopathic urticaria.

How Fexo Works (Pharmacology)

Fexofenadine works by targeting the H1 histamine receptor. When allergens are encountered, mast cells and basophils release histamine and other inflammatory mediators. Histamine then binds to and activates H1 receptors, leading to various allergic symptoms like itching, runny nose, and watery eyes.

• Fexofenadine is an "inverse agonist" of the H1 receptor. This means it binds to and stabilizes the inactive form of the receptor, preventing its activation and the subsequent cascade of allergic reactions.
• It has a potent and selective affinity for H1 receptors and does not exhibit antidopaminergic, antiserotonergic, anticholinergic, sedative, or adrenergic blocking activity.
• Crucially, Fexofenadine does not cross the blood-brain barrier, which means it is unlikely to cause significant central nervous system (CNS) effects like drowsiness, distinguishing it from older antihistamines.

Key Indications & Benefits

Fexo is indicated for the symptomatic treatment of:

• Seasonal and perennial allergic rhinitis (in adults and children 12 years and over). Symptoms effectively treated include: sneezing, rhinorrhea (runny nose), lacrimation (tearing), itchy, red eyes, and itchy nose/palate/throat.
• Chronic idiopathic urticaria (chronic hives without a known cause).

Dosage & Administration

Always consult a registered physician for medication use.

Allergic Rhinitis:

• Adults and children 12 years and older (Tablet): 60 mg twice daily OR 120 mg once daily OR 180 mg once daily.
  • In case of impaired renal function: 60 mg once daily.
• Children from 6 to 11 years (Tablet): 30 mg twice daily OR 60 mg once daily.
  • In case of impaired renal function: 30 mg once daily.
• Children from 2 to 11 years (Suspension): 30 mg or 5 ml twice daily.
  • In case of impaired renal function: 30 mg or 5 ml once daily.

Chronic Idiopathic Urticaria:

• Adults and children 12 years and older (Tablet): 60 mg twice daily OR 120 mg once daily OR 180 mg once daily.
  • In case of impaired renal function: 60 mg once daily.
• Children from 6 to 11 years (Tablet): 30 mg twice daily OR 60 mg once daily.
  • In case of impaired renal function: 30 mg once daily.
• Children from 6 months to less than 2 years (Suspension): 15 mg or 2.5 ml (1/2 tsp) twice daily.
  • In case of impaired renal function: 15 mg or 2.5 ml (1/2 tsp) once daily.
• Children from 2 to 11 years (Suspension): 30 mg or 5 ml (1 tsp) twice daily.
  • In case of impaired renal function: 30 mg or 5 ml (1 tsp) once daily.

Important Considerations & Warnings

It is crucial to discuss your full medical history with your doctor before taking Fexo.

Contraindications:

• Patients with known hypersensitivity to Fexofenadine Hydrochloride or any of its ingredients.

Side Effects:

• Common (Adults, similar to placebo): Headache, drowsiness, dizziness, nausea, fatigue.
• Post-marketing surveillance (frequency not known):
  • Immune system disorders: Hypersensitivity reactions (e.g., angioedema, chest tightness, dyspnea, flushing, systemic anaphylaxis).
  • Psychiatric disorders: Insomnia, nervousness, sleep disorders or nightmares/excessive dreaming (paroniria).
  • Cardiac disorders: Tachycardia (fast heart rate), palpitations.
  • Gastrointestinal disorders: Diarrhea.
  • Skin and subcutaneous tissue disorders: Rash, urticaria (hives), pruritus (itching).

Pregnancy & Lactation:

• Pregnancy: There are no adequate data on Fexofenadine use in pregnant women. Limited animal studies show no direct or indirect harmful effects on pregnancy or fetal development. Fexofenadine should not be used during pregnancy unless clearly necessary.
• Lactation: It is not known if Fexofenadine is excreted in human milk. However, it was found in breast milk when the related drug Terfenadine was administered to nursing mothers. Therefore, Fexofenadine is not recommended for breastfeeding mothers.
• Fertility: No human data. No effect on fertility in mice.

Precautions & Warnings:

• Elderly and Renally/Hepatically Impaired Patients: Limited data; administer with care in these groups.
• Cardiovascular Disease: Patients with a history of or ongoing cardiovascular disease should be aware that antihistamines, as a class, have been associated with adverse reactions like tachycardia and palpitations.
• Driving/Operating Machines: Fexo is unlikely to affect the ability to drive or use machines, as it generally has no significant CNS effects. However, individual response should be checked before performing tasks requiring concentration.

Drug Interactions:

• No Hepatic Biotransformation: Fexo does not undergo liver metabolism, so it will not interact with other drugs via hepatic mechanisms.
• Erythromycin or Ketoconazole: Co-administration results in a 2-3 times increase in plasma Fexofenadine levels. This change was not associated with QTc prolongation or increased adverse reactions compared to single use.
• Omeprazole: No interaction observed.
• Aluminum and Magnesium Hydroxide-containing Antacids: Administration 15 minutes prior to Fexo caused a reduction in bioavailability, likely due to binding in the gastrointestinal tract. It is advisable to leave 2 hours between administration of Fexo and these antacids.

Overdose Effects

• Reported symptoms: Dizziness, drowsiness, fatigue, and dry mouth.
• Single doses up to 800 mg and prolonged doses have been administered to healthy subjects without clinically significant adverse reactions. The maximum tolerated dose is not established.
• Management:
  • Consider standard measures to remove any unabsorbed medicinal product.
  • Symptomatic and supportive treatment is recommended.
  • Hemodialysis does not effectively remove Fexo from blood.

Storage Conditions

Keep in a dry place away from light and heat. Keep out of the reach of children.