FEXOFENADINE HYDROCHLORIDE; PSEUDOEPHEDRINE HYDROCHLORIDE

Clinical safety rating: safe

MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.

How it works

Fexofenadine is a selective peripheral H1-receptor antagonist; pseudoephedrine is a sympathomimetic amine that acts as a decongestant by stimulating alpha-adrenergic receptors in the respiratory tract mucosa, causing vasoconstriction.

What the body does with it

Metabolism	Fexofenadine: minimally metabolized (5%) by CYP3A4; pseudoephedrine: partially metabolized by N-demethylation (liver), mostly excreted unchanged.
Excretion	Fexofenadine: 80% unchanged in feces, 11% in urine. Pseudoephedrine: 70-90% unchanged in urine.
Half-life	Fexofenadine: 14.4 hours. Pseudoephedrine: 5-8 hours, prolonged in renal impairment.
Protein binding	Fexofenadine: 60-70% (albumin and α1-acid glycoprotein). Pseudoephedrine: 20-30% (albumin).
Volume of Distribution	Fexofenadine: 5.4-5.8 L/kg. Pseudoephedrine: 2.6-3.5 L/kg.
Bioavailability	Fexofenadine: 30-40% (oral). Pseudoephedrine: 100% (oral, well absorbed).
Onset of Action	Fexofenadine: 1-2 hours. Pseudoephedrine: 30 minutes (oral).
Duration of Action	Fexofenadine: 24 hours. Pseudoephedrine: 4-6 hours.

Classification & Brands

Dosing & administration

One tablet (fexofenadine HCl 60 mg / pseudoephedrine HCl 120 mg) orally every 12 hours. Maximum 2 tablets per day.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	Contraindicated in severe renal impairment (CrCl <60 mL/min). For moderate impairment (CrCl 60-90 mL/min): use with caution; consider reducing dose interval to every 24 hours. No specific dose reduction established; use not recommended in CrCl <60 mL/min.
Liver impairment	No specific dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C); use with caution.
Pediatric use	Children ≥12 years: same as adult dose (one tablet every 12 hours). For children <12 years: safety and efficacy not established; alternative formulations recommended.
Geriatric use	Elderly patients may be more sensitive to CNS and anticholinergic effects of pseudoephedrine. Use with caution; consider lower starting dose or extended dosing interval. Contraindicated if CrCl <60 mL/min (common in elderly).

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.

FDA category	Animal
Breastfeeding	Excreted in breast milk; pseudoephedrine: M/P ratio ~3.3-3.5. Fexofenadine: M/P ratio unknown but likely low. Pseudoephedrine may cause irritability, sleep disturbances in infants. Avoid or use with caution; consider risk-benefit.
Teratogenic Risk	FDA Pregnancy Category C. Inadequate human studies; animal studies show fetal harm, including reduced fetal weight and skeletal variations. First trimester: risk of neural tube defects? insufficient data. Second/third trimester: risk of premature closure of ductus arteriosus (pseudoephedrine). Avoid use, especially in first trimester and near term.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Insomnia
Serious Effects

Absolute Contraindications

["Severe hypertension","Severe coronary artery disease","Concurrent or recent (within 14 days) MAOI therapy","Narrow-angle glaucoma","Urinary retention","Hypersensitivity to any component"]

Clinical Precautions

Precautions

["Cardiovascular effects (hypertension, arrhythmias, palpitations)","CNS stimulation (insomnia, nervousness, dizziness)","Risk of urinary retention (especially in males with prostatic hypertrophy)","Increased intraocular pressure (angle-closure glaucoma)","Severe cutaneous reactions (rare)","Drug interactions: MAOIs, beta-blockers, digoxin, antacids."]

Clinical Tips & Counseling

Drug interactions

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FEXOFENADINE HYDROCHLORIDE; PSEUDOEPHEDRINE HYDROCHLORIDE

Clinical safety rating: safe

MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.

How it works

What the body does with it

Metabolism	Fexofenadine: minimally metabolized (5%) by CYP3A4; pseudoephedrine: partially metabolized by N-demethylation (liver), mostly excreted unchanged.
Excretion	Fexofenadine: 80% unchanged in feces, 11% in urine. Pseudoephedrine: 70-90% unchanged in urine.
Half-life	Fexofenadine: 14.4 hours. Pseudoephedrine: 5-8 hours, prolonged in renal impairment.
Protein binding	Fexofenadine: 60-70% (albumin and α1-acid glycoprotein). Pseudoephedrine: 20-30% (albumin).
Volume of Distribution	Fexofenadine: 5.4-5.8 L/kg. Pseudoephedrine: 2.6-3.5 L/kg.
Bioavailability	Fexofenadine: 30-40% (oral). Pseudoephedrine: 100% (oral, well absorbed).
Onset of Action	Fexofenadine: 1-2 hours. Pseudoephedrine: 30 minutes (oral).
Duration of Action	Fexofenadine: 24 hours. Pseudoephedrine: 4-6 hours.

Classification & Brands

Dosing & administration

One tablet (fexofenadine HCl 60 mg / pseudoephedrine HCl 120 mg) orally every 12 hours. Maximum 2 tablets per day.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	Contraindicated in severe renal impairment (CrCl <60 mL/min). For moderate impairment (CrCl 60-90 mL/min): use with caution; consider reducing dose interval to every 24 hours. No specific dose reduction established; use not recommended in CrCl <60 mL/min.
Liver impairment	No specific dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C); use with caution.
Pediatric use	Children ≥12 years: same as adult dose (one tablet every 12 hours). For children <12 years: safety and efficacy not established; alternative formulations recommended.
Geriatric use	Elderly patients may be more sensitive to CNS and anticholinergic effects of pseudoephedrine. Use with caution; consider lower starting dose or extended dosing interval. Contraindicated if CrCl <60 mL/min (common in elderly).

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.

FDA category	Animal
Breastfeeding	Excreted in breast milk; pseudoephedrine: M/P ratio ~3.3-3.5. Fexofenadine: M/P ratio unknown but likely low. Pseudoephedrine may cause irritability, sleep disturbances in infants. Avoid or use with caution; consider risk-benefit.
Teratogenic Risk	FDA Pregnancy Category C. Inadequate human studies; animal studies show fetal harm, including reduced fetal weight and skeletal variations. First trimester: risk of neural tube defects? insufficient data. Second/third trimester: risk of premature closure of ductus arteriosus (pseudoephedrine). Avoid use, especially in first trimester and near term.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Insomnia
Serious Effects

Absolute Contraindications

["Severe hypertension","Severe coronary artery disease","Concurrent or recent (within 14 days) MAOI therapy","Narrow-angle glaucoma","Urinary retention","Hypersensitivity to any component"]