ALLERFED
Clinical safety rating
cautionComprehensive clinical and safety monograph for ALLERFED (ALLERFED).
ALLERFED is a combination of an antihistamine (fexofenadine) and a decongestant (pseudoephedrine). Fexofenadine is a selective peripheral H1-receptor antagonist that blocks histamine effects, reducing allergy symptoms. Pseudoephedrine is a sympathomimetic amine that acts as a decongestant via alpha-adrenergic receptor activation, causing vasoconstriction of nasal mucosa.
| Metabolism | Fexofenadine is minimally metabolized (<5%) in the liver; primarily excreted unchanged in feces (80%) and urine (11%). Pseudoephedrine is partially metabolized in the liver by N-demethylation and excreted mostly unchanged in urine. |
| Excretion | Primarily renal (approximately 60-70% as unchanged drug and metabolites); minor biliary (10-15%); fecal (5-10%). |
| Half-life | Terminal elimination half-life 20-24 hours; clinically significant for once-daily dosing in seasonal allergic rhinitis. |
| Protein binding | 80-85% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd 5-7 L/kg, indicating extensive tissue distribution beyond plasma volume. |
| Bioavailability | Oral: 40-50% due to first-pass metabolism; intranasal: 70-80%. |
| Onset of Action | Oral: 1-2 hours; intranasal: 30 minutes. |
| Duration of Action | Oral: 24 hours; intranasal: 12-24 hours. Note: continuous use may require dose adjustment. |
| Molecular Weight | 470.5 |
1 tablet (pseudoephedrine 60 mg / triprolidine 2.5 mg) orally every 4-6 hours; not to exceed 4 doses per 24 hours.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-50 mL/min: administer every 6-8 hours. CrCl 10-29 mL/min: administer every 8-12 hours. CrCl <10 mL/min: not recommended. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose by 50% or extend interval. Child-Pugh Class C: avoid use. |
| Pediatric use | Children 6-12 years: 1/2 tablet (pseudoephedrine 30 mg / triprolidine 1.25 mg) orally every 4-6 hours; max 2 doses per 24 hours. Children <6 years: not recommended. |
| Geriatric use | Initiate at half the adult dose; monitor for anticholinergic effects, dizziness, and hypertension; maximum 2 doses per 24 hours. |
| 1st trimester | Avoid during first trimester. Animal studies have shown teratogenic effects, and there are no adequate human studies. Use only if potential benefit justifies risk to fetus. |
| 2nd trimester | Use with caution. No well-controlled studies in pregnant women. Consider risk-benefit. |
| 3rd trimester | Use with caution in third trimester due to potential for uterine contractions or premature labor. Avoid near term. |
Clinical note
Comprehensive clinical and safety monograph for ALLERFED (ALLERFED).
| Placental transfer | Crosses placenta. Animal studies show placental transfer. Human data limited; assume transfer. |
| Breastfeeding | Excreted in breast milk in low amounts. No reports of adverse effects in nursing infants. However, due to anticholinergic and sedative properties, monitor infant for drowsiness or irritability. Use with caution, especially in neonates or premature infants. |
| Lactation Rating | L3 - Limited Data (likely safe but monitor) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: Limited human data; animal studies suggest possible increased risk of minor malformations. Second/third trimester: Use associated with reduced uterine blood flow and fetal tachycardia; avoid near term due to risk of prolonged QT interval in neonate. |
| Fetal Monitoring | Monitor fetal heart rate and uterine activity during labor if used systemically. Assess for maternal hypotension and fetal distress. Cardiac monitoring in neonates exposed near term for QT prolongation. |
| Fertility Effects | No significant adverse effects on fertility reported in animal studies. May cause transient sedation affecting libido. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to drug or any componentSevere hypertensionCoronary artery diseaseNarrow-angle glaucomaUrinary retentionConcurrent use with monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOIs
| Precautions | Severe hypertension, Coronary artery disease, Ischemic heart disease, Increased intraocular pressure, Diabetes, Thyroid disease, Prostatic hypertrophy, Renal impairment, Use with caution in elderly, Avoid with MAOIs or within 14 days of stopping |
| Food/Dietary | Avoid high-tyramine foods (e.g., aged cheeses, cured meats, fermented foods) if taking MAOIs concurrently. Grapefruit juice may increase absorption of triprolidine. Caffeine may enhance stimulant effects of pseudoephedrine. |
| Clinical Pearls | Allerfed combines pseudoephedrine and triprolidine. Use with caution in hypertension, cardiovascular disease, and glaucoma. Avoid in patients with severe hypertension or coronary artery disease. Limit duration to 5-7 days to avoid rebound congestion. Anticholinergic effects may cause urinary retention in BPH. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Do not exceed recommended dose; avoid taking more than every 4-6 hours. · Avoid alcohol while taking this medication. · If symptoms persist for more than 7 days, consult your doctor. · May cause drowsiness; avoid driving or operating heavy machinery until you know how you react. |
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