LORATADINE AND PSEUDOEPHEDRINE SULFATE
Clinical safety rating: safe
MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.
Loratadine: Selective peripheral H1-receptor antagonist, reducing histamine-mediated allergic responses. Pseudoephedrine sulfate: Indirect sympathomimetic, releasing norepinephrine from presynaptic terminals, causing vasoconstriction and decongestion.
| Metabolism | Loratadine: Metabolized by CYP3A4 and CYP2D6 to active metabolite desloratadine. Pseudoephedrine: Partially metabolized by hepatic N-demethylation and excreted largely unchanged in urine. |
| Excretion | Loratadine and its metabolites are primarily excreted in urine (approximately 80%) and feces (approximately 20%). Pseudephedrine is predominantly excreted unchanged in urine (70-90%), with the remainder as inactive metabolites. |
| Half-life | Loratadine: 8-14 hours (terminal); its active metabolite descarboethoxyloratadine: 17-24 hours. Pseudephedrine sulfate: 5-8 hours (dependent on urine pH; alkaline urine prolongs half-life). |
| Protein binding | Loratadine: 97-99% bound to albumin and alpha-1-acid glycoprotein. Pseudephedrine sulfate: minimal binding (<5%). |
| Volume of Distribution | Loratadine: 122 L/kg (extensive tissue distribution). Pseudephedrine sulfate: 2.5-3.5 L/kg. |
| Bioavailability | Loratadine: Oral bioavailability ~40% (due to extensive first-pass metabolism). Pseudephedrine sulfate: Oral bioavailability ~100%. |
| Onset of Action | Loratadine: 1-3 hours orally. Pseudephedrine sulfate: 30-60 minutes orally. |
| Duration of Action | Loratadine: 24 hours. Pseudephedrine sulfate: 4-6 hours (sustained-release formulation may last up to 12 hours). Note: Clinical effect duration may vary with dosing formulation. |
| Molecular Weight | Loratadine 382.88 Da; Pseudoephedrine sulfate 428.54 Da (pseudoephedrine base 165.23 Da) |
| Action Class | Antihistamine (second-generation) and sympathomimetic decongestant combination |
One tablet (loratadine 5 mg/pseudoephedrine sulfate 120 mg) orally every 12 hours. Maximum: 2 tablets per day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | Contraindicated if GFR < 30 mL/min. For GFR 30–50 mL/min: use with caution, consider reducing dose (e.g., loratadine 5 mg/pseudoephedrine sulfate 60 mg) every 12 hours. For GFR > 50 mL/min: no adjustment needed. |
| Liver impairment | Child-Pugh Class A or B: no adjustment. Child-Pugh Class C: loratadine should be avoided; consider alternative therapy. |
| Pediatric use | Children ≥12 years: same as adult dose (one tablet every 12 hours). Children 4–11 years: use loratadine 2.5 mg/pseudoephedrine sulfate 60 mg tablet every 12 hours; maximum 2 tablets per day. Children <4 years: not recommended. |
| Geriatric use | Elderly (≥65 years): start with lowest effective dose; due to increased sensitivity to sympathomimetics, consider loratadine alone. Use with caution for hypertension, arrhythmias, or prostatic hyperplasia. |
| 1st trimester | Avoid due to potential teratogenicity from pseudoephedrine (vascular disruption) and limited safety data; use only if benefit outweighs risk. |
| 2nd trimester | Use with caution; pseudoephedrine may reduce uterine blood flow and cause fetal tachycardia. Preferred antihistamine alternative is loratadine alone. |
| 3rd trimester | Avoid near term; pseudoephedrine may cause uterine irritability and fetal tachycardia; loratadine is generally safe. |
Clinical note
MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.
| FDA category | Animal |
| Placental transfer | Both drugs cross the placenta; loratadine (approx. 40% of maternal plasma) and pseudoephedrine (readily crosses, achieving fetal levels similar to maternal). |
| Breastfeeding |
■ FDA Black Box Warning
None
| Common Effects | Insomnia |
| Serious Effects | Cardiac arrhythmias (e.g., ventricular tachycardia, atrial fibrillation), Hypertensive crisis, Myocardial infarction, Stroke, Seizures, Severe allergic reactions (e.g., anaphylaxis, angioedema), Acute urinary retention (especially in men with prostatic hypertrophy), Ischemic colitis |
Severe hypertensionCoronary artery diseaseMAOI use within 14 daysNarrow-angle glaucomaUrinary retentionSevere renal impairment
| Precautions | Do not use with other antihistamines or decongestants, Caution in patients with hypertension, cardiovascular disease, hyperthyroidism, diabetes, increased intraocular pressure, or prostatic hypertrophy, May cause dizziness or drowsiness; avoid driving or operating machinery, Avoid use with MAO inhibitors or within 14 days of stopping |
| Food/Dietary |
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| Loratadine is excreted into breast milk in low levels (relative infant dose approx. 1.1%); pseudoephedrine transfers into milk and may cause irritability or decreased milk supply. Use with caution, especially in preterm neonates or compromised infants. |
| Lactation Rating | L3 (Limited data; caution advised) |
| Teratogenic Risk | Loratadine: FDA Pregnancy Category B; no evidence of teratogenicity in animal studies, but no adequate human studies in first trimester. Pseudophedrine: FDA Pregnancy Category C; associated with increased risk of gastroschisis in first trimester, and may cause uterine vasoconstriction reducing placental perfusion in second and third trimesters. Avoid in first trimester due to potential vascular disruption defects. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of excessive stimulation (insomnia, nervousness). Fetal monitoring: assess for potential growth restriction if used chronically; consider nonstress test if evidence of reduced placental perfusion. |
| Fertility Effects | No known significant adverse effects on fertility with loratadine. Pseudoephedrine may theoretically affect uterine blood flow; no direct evidence of impaired fertility. |
| Take with or without food; food does not significantly affect absorption. Avoid alcohol as it may increase drowsiness or dizziness. Limit caffeine intake as pseudoephedrine can cause additive stimulation. |
| Clinical Pearls | Loratadine/pseudoephedrine sulfate is a fixed-dose combination for allergic rhinitis with nasal congestion. Pseudoephedrine is a sympathomimetic with potential for CNS stimulation, tachycardia, and increased blood pressure; use cautiously in hypertension, hyperthyroidism, cardiac disease, and glaucoma. Loratadine is a second-generation antihistamine with minimal sedation. Avoid use with MAOIs or within 14 days of discontinuation. Contraindicated in severe hypertension, coronary artery disease, and concurrent MAOI use. |
| Patient Advice | Avoid driving or operating machinery until you know how this medication affects you; although loratadine is less sedating, pseudoephedrine may cause dizziness or nervousness. · Do not take this medication if you have high blood pressure, heart disease, glaucoma, or an overactive thyroid unless directed by your doctor. · Do not exceed the recommended dose; taking more may increase the risk of side effects like rapid pulse, difficulty urinating, or insomnia. · Avoid taking this medication within 14 days of taking an MAO inhibitor (e.g., isocarboxazid, linezolid, phenelzine, selegiline, tranylcypromine) as dangerous drug interactions can occur. · Report palpitations, chest pain, severe dizziness, or difficulty urinating to your healthcare provider. |