Fexofenadine Hydrochloride and Pseudoephedrine Hydrochloride Combination Medications
Pharmacological Classification
This medication is a combination product classified as an antihistamine and a decongestant.
Mechanism of Action
Fexofenadine Hydrochloride
Fexofenadine is a histamine H1-receptor antagonist. It selectively binds to H1-receptors, thereby blocking the action of histamine, which is responsible for many allergic symptoms. It does not readily cross the blood-brain barrier, resulting in minimal sedative effects compared to first-generation antihistamines.
Pseudoephedrine Hydrochloride
Pseudoephedrine is a sympathomimetic amine that acts as an alpha- and beta-adrenergic receptor agonist. Its decongestant effect is primarily due to its alpha-adrenergic activity, which causes vasoconstriction in the nasal mucosa, leading to reduced swelling and congestion.
Therapeutic Indications
This combination is indicated for the relief of symptoms associated with seasonal allergic rhinitis, including sneezing, runny nose, itchy, watery eyes, and nasal congestion.
Dosage and Administration
Dosage recommendations vary depending on the specific product strength and the patient's age and renal function. It is typically administered orally. Prolonged use should be medically supervised.
Adverse Effects
Common adverse effects may include headache, dry mouth, insomnia, nervousness, and dizziness. Less common but more serious side effects are possible and necessitate medical consultation. Cardiovascular effects are possible due to the pseudoephedrine component, particularly in individuals with pre-existing heart conditions.
Contraindications
This combination is contraindicated in patients with known hypersensitivity to either fexofenadine or pseudoephedrine, or any of the inactive ingredients. It is also contraindicated in patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping MAOI treatment. Caution is advised in patients with hypertension, cardiovascular disease, diabetes mellitus, hyperthyroidism, increased intraocular pressure, or prostatic hypertrophy.
Drug Interactions
Potential drug interactions include interactions with MAOIs, sympathomimetic agents, and certain antacids that may affect the absorption of fexofenadine.
Pharmacokinetics
Fexofenadine Hydrochloride
Fexofenadine is rapidly absorbed following oral administration. It is primarily eliminated unchanged in the feces and urine. It exhibits linear pharmacokinetics over the recommended dosage range.
Pseudoephedrine Hydrochloride
Pseudoephedrine is readily absorbed after oral administration. It is primarily excreted unchanged in the urine. Its elimination is pH-dependent, with faster elimination occurring in acidic urine.