Usage
Fexofenadine + Pseudoephedrine is prescribed for the relief of symptoms associated with seasonal allergic rhinitis (hay fever) and other upper respiratory allergies, particularly when nasal congestion is a prominent symptom. This combination medication addresses both the allergic and congestion components.
- Pharmacological Classification: This drug is a combination of an antihistamine (fexofenadine) and a decongestant (pseudoephedrine).
- Mechanism of Action: Fexofenadine acts as a selective peripheral H1-receptor antagonist, inhibiting the effects of histamine, a key mediator in allergic reactions. This action reduces symptoms like sneezing, rhinorrhea, and itching. Pseudoephedrine is a sympathomimetic amine that acts as an alpha-adrenergic agonist, constricting blood vessels in the nasal mucosa. This vasoconstriction reduces nasal congestion.
Alternate Names
Fexofenadine-Pseudoephedrine
Brand Names: Allegra-D, Telfast Decongestant, Xadine Plus.
How It Works
Pharmacodynamics: Fexofenadine selectively blocks peripheral H1 receptors, mitigating histamine’s effects on smooth muscle, vascular permeability, and sensory nerve endings. Pseudoephedrine activates alpha-adrenergic receptors, leading to vasoconstriction and reduced nasal congestion.
Pharmacokinetics:
- Fexofenadine: Absorbed rapidly after oral administration. Peak plasma concentrations reached in approximately 1-3 hours. Minimally metabolized, primarily excreted unchanged in feces and urine. Half-life of 11-15 hours.
- Pseudoephedrine: Readily absorbed from the GI tract. Partially metabolized in the liver. Excreted primarily in urine. Half-life varies, around 6 hours.
Mode of Action: Fexofenadine acts by competitive antagonism at the H1-receptor site, preventing histamine from binding and initiating the allergic cascade. Pseudoephedrine directly stimulates alpha-adrenergic receptors on vascular smooth muscle, causing vasoconstriction.
Elimination Pathways: Fexofenadine primarily eliminated through fecal and renal excretion. Pseudoephedrine is primarily eliminated through renal excretion.
Dosage
Standard Dosage
Adults:
One 12-hour combination tablet (60 mg fexofenadine/120 mg pseudoephedrine) every 12 hours or one 24-hour combination tablet (180 mg fexofenadine/240 mg pseudoephedrine) once daily. Administer on an empty stomach with water.
Children:
Not recommended for children under 12 years of age for combination products. Refer to individual components for younger age groups.
Special Cases:
- Elderly Patients: Start with a lower dose due to increased sensitivity to sympathomimetic amines.
- Patients with Renal Impairment: Lower initial dose recommended (e.g., one 12-hour tablet daily) due to decreased elimination of both components. Avoid the 24-hour formulation.
- Patients with Hepatic Dysfunction: No dosage adjustment is typically needed for fexofenadine.
- Patients with Comorbid Conditions: Exercise caution in patients with hypertension, cardiovascular disease, hyperthyroidism, diabetes, and prostatic hypertrophy.
Clinical Use Cases The combination of fexofenadine and pseudoephedrine is specifically intended to manage symptoms of seasonal allergic rhinitis with associated nasal congestion. It is not typically used in the specific clinical settings mentioned. For intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations, medications like sedatives, analgesics, and vasopressors are more relevant.
Dosage Adjustments
Dose adjustments are required for renal impairment (see above). Monitor patients with comorbid conditions for potential exacerbation of their conditions.
Side Effects
Common Side Effects
Headache, dry mouth, nausea, dizziness, insomnia, nervousness, dyspepsia.
Rare but Serious Side Effects
Allergic reactions (e.g., rash, itching, swelling, severe dizziness, difficulty breathing), palpitations, tachycardia, hypertension, hallucinations, seizures.
Long-Term Effects
Long-term effects of combined use are not well-established, but prolonged use of pseudoephedrine can lead to tolerance and rebound congestion.
Adverse Drug Reactions (ADR)
Severe hypersensitivity reactions, significant cardiovascular effects (e.g., arrhythmias, MI), CNS stimulation (e.g., seizures).
Contraindications
Hypersensitivity to fexofenadine, pseudoephedrine, or any components; narrow-angle glaucoma; urinary retention; severe hypertension or coronary artery disease; concurrent or recent (within 14 days) MAOI therapy.
Drug Interactions
MAOIs, antacids (aluminum or magnesium containing), anticholinergics, other sympathomimetics, beta-blockers, digoxin, some antidepressants, and certain antifungals. Alcohol may increase certain side effects. Fruit juices (especially grapefruit, orange, and apple) can reduce the absorption of fexofenadine.
Pregnancy and Breastfeeding
-
Pregnancy Safety Category: While older pregnancy categories are phased out, caution is advised. Consult guidelines for updated advice. Use only if the potential benefit outweighs the potential risk to the fetus. Pseudoephedrine is generally avoided during the first trimester due to a possible association with gastroschisis and small intestinal atresia.
-
Breastfeeding: Fexofenadine is present in breast milk at low levels. Pseudoephedrine can reduce milk production. Not generally recommended unless the benefits outweigh the potential risks to the infant. Monitor for irritability in infants.
Drug Profile Summary
- Mechanism of Action: Antihistamine (fexofenadine) and decongestant (pseudoephedrine).
- Side Effects: Headache, dry mouth, nausea, dizziness, insomnia, nervousness. Rarely: allergic reactions, cardiovascular effects, CNS stimulation.
- Contraindications: Hypersensitivity, glaucoma, urinary retention, severe hypertension or CAD, MAOI use.
- Drug Interactions: MAOIs, antacids, sympathomimetics, fruit juices.
- Pregnancy & Breastfeeding: Consult guidelines. Use with caution. Pseudoephedrine can decrease milk production.
- Dosage: Adults: 60/120 mg BID or 180/240 mg daily. Renal impairment: dose reduction needed.
- Monitoring Parameters: Blood pressure, heart rate, allergy symptoms, nasal congestion, signs of adverse reactions.
Popular Combinations (This combination is a popular combination, generally not combined with further medication. Single-ingredient medications are favored for other combination therapies)
Precautions
Screen patients for contraindications and potential drug interactions. Caution in patients with renal impairment, hypertension, cardiovascular disease, hyperthyroidism, diabetes, and prostatic hypertrophy. Avoid alcohol. Take on an empty stomach with water, avoid fruit juices. Driving impairment is possible.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Fexofenadine + Pseudoephedrine?
A: Adults: One 12-hour combination tablet (60 mg fexofenadine/120 mg pseudoephedrine) every 12 hours OR one 24-hour combination tablet (180 mg fexofenadine/240 mg pseudoephedrine) once daily. Dose adjustment is needed for renal impairment. Not recommended for children under 12.
Q2: Can pregnant or breastfeeding women take Fexofenadine + Pseudoephedrine?
A: Consult current guidelines and weigh risks versus benefits. Pseudoephedrine may reduce milk production and is associated with potential fetal risks. Safer alternatives may be preferred.
Q3: What are the common side effects of Fexofenadine + Pseudoephedrine?
A: Common side effects include headache, dry mouth, nausea, dizziness, insomnia, and nervousness.
Q4: What are the serious side effects to watch out for?
A: Rarely, severe allergic reactions, cardiovascular effects (e.g., palpitations, arrhythmias), or CNS stimulation can occur.
Q5: What should patients avoid while taking this medication?
A: Avoid alcohol, MAOIs, certain antacids, and fruit juices. Caution with driving or operating machinery.
Q6: How does renal impairment affect dosing?
A: Reduced renal function requires a lower initial dose (e.g., one 12-hour tablet daily). The 24-hour formulation should be avoided in patients with renal impairment.
Q7: Does this combination interact with other medications?
A: Yes, potential interactions exist with MAOIs, antacids, anticholinergics, other sympathomimetics, and certain antifungals.
Q8: What are the contraindications to using this medication?
A: Contraindications include hypersensitivity, narrow-angle glaucoma, urinary retention, severe hypertension or coronary artery disease, and concurrent/recent MAOI therapy.
Q9: Can Fexofenadine + Pseudoephedrine be used in children?
A: The combination product is not generally recommended for children under 12. Fexofenadine alone is available for younger children.
Q10: How should this medicine be administered?
A: Administer on an empty stomach with water. Swallow tablets whole; do not crush, chew, or dissolve.
