Medication Name: Allegra

Active Ingredient

Fexofenadine hydrochloride is the active ingredient in Allegra. It is a second-generation antihistamine and a selective peripheral H1-blocker. Fexofenadine is a non-sedating antihistamine that works by reducing the effects of histamine in the body.

Indications and Usage

Allegra is indicated for the relief of symptoms associated with seasonal allergic rhinitis in adults and children 12 years and older. It alleviates sneezing, rhinorrhea, pruritus, and lacrimation. This medication is also indicated for the treatment of uncomplicated skin manifestations of chronic idiopathic urticaria.

Dosage Forms

Allegra is available in several dosage forms. These include oral tablets (30 mg, 60 mg, and 180 mg), orally disintegrating tablets (30 mg), and oral suspension (30 mg/5 mL). These varied forms facilitate tailored dosing for different patient needs and preferences.

Dosage and Administration

Adults and children 12 years and older with seasonal allergic rhinitis are recommended to take 60 mg twice daily or 180 mg once daily with water. For chronic idiopathic urticaria, the dosage is the same. No adjustment is necessary in patients 12 years and older with decreased renal function. The oral suspension should be shaken well before use and measured with a dosing spoon or oral syringe.

Pharmacokinetics

Fexofenadine has rapid absorption with a peak plasma concentration reached in approximately 1-3 hours. It is 60-70% protein-bound in serum. Fexofenadine is not significantly metabolized by the liver and undergoes limited metabolism, with approximately 11% of the dose excreted unchanged in the urine. The terminal elimination half-life is 14.4 hours after multiple dosing in healthy subjects.

Drug Interactions

Significant drug interactions with fexofenadine include antacids containing aluminum or magnesium, which should not be taken within 15 minutes of Allegra. Co-administration with ketoconazole or erythromycin increases fexofenadine plasma levels. Concomitant use with fruit juices, particularly grapefruit, orange, and apple, may decrease the bioavailability of fexofenadine.

Contraindications

Allegra is contraindicated in patients with known hypersensitivity to fexofenadine or any of its ingredients. It is also contraindicated in patients with severe renal impairment due to potential accumulation of the drug in the body.

Mechanism of Action

Fexofenadine works by selectively inhibiting peripheral H1 receptors. By blocking H1 receptors, it prevents the action of endogenous histamine, which results in diminished allergic symptoms such as nasal congestion, vasodilation, and increased vascular permeability.

Special Populations

Pharmacokinetic data suggest no substantial differences in efficacy or safety in elderly patients compared to younger adults. Caution is recommended in patients with renal impairment, and adjustment may be necessary. Limited observational data in pregnant women have shown no increase in major malformations, but it should be used during pregnancy only if clearly needed.

Clinical Studies

Allegra has been evaluated in multiple placebo-controlled clinical trials. Studies have shown significant improvement in allergic rhinitis symptoms compared to placebo. In chronic idiopathic urticaria, Allegra significantly reduced itching and wheal size. These trials provide strong evidence of Allegra’s efficacy and safety in treating both conditions.

Adverse Reactions

The most common adverse reactions observed include headache, drowsiness, dizziness, and nausea. Other less frequent side effects include fatigue, dyspepsia, and back pain. Most adverse reactions are mild to moderate in severity and typically resolve without intervention.

Storage and Handling

Allegra should be stored at controlled room temperature, between 20°C to 25°C (68°F to 77°F). The oral suspension should be discarded after 30 days of opening. Keep out of reach of children to prevent accidental ingestion, and ensure the container is tightly closed after each use.

Overdosage

Overdose is generally characterized by dizziness, dry mouth, and fatigue. In case of overdose, supportive treatment is recommended. Hemodialysis does not remove a significant amount of fexofenadine from the blood. Immediate medical attention is advisable for cases of severe overdose.

Patient Counseling

Instruct patients to take Allegra with water and advise against consuming fruit juices concurrently. Patients should be informed about the potential for drowsiness and should avoid engaging in activities requiring mental alertness until they know how the medication affects them. Emphasize adherence to recommended dosage schedules for optimal therapeutic outcomes.