TRIPROLIDINE AND PSEUDOEPHEDRINE
Clinical safety rating: safe
CNS depressants may enhance sedative effects May cause marked drowsiness and impair mental and physical abilities.
Triprolidine is a first-generation antihistamine that antagonizes histamine H1 receptors, reducing histamine-mediated allergic symptoms. Pseudoephedrine is a sympathomimetic amine that acts as a decongestant by stimulating alpha-adrenergic receptors in the respiratory tract mucosa, causing vasoconstriction and decreased nasal congestion.
| Metabolism | Triprolidine is metabolized via hepatic hydroxylation and conjugation. Pseudoephedrine is partially metabolized in the liver by N-demethylation to inactive metabolites; the remainder is excreted unchanged in urine. |
| Excretion | Triprolidine: renal, 70% unchanged and metabolites. Pseudoephedrine: renal, 90% unchanged. |
| Half-life | Triprolidine: 2-4 hours (parent compound). Pseudoephedrine: 4-8 hours, prolonged in alkaline urine (up to 16-24 hours). |
| Protein binding | Triprolidine: ~90% bound to plasma proteins. Pseudoephedrine: <10% bound. |
| Volume of Distribution | Triprolidine: ~2.5-3.5 L/kg. Pseudoephedrine: ~2.5-3.5 L/kg. |
| Bioavailability | Oral: Triprolidine ~70-80%; Pseudoephedrine ~80-90% (immediate-release). |
| Onset of Action | Oral: Triprolidine ~30 minutes; Pseudoephedrine ~30-60 minutes. |
| Duration of Action | Immediate-release: 4-6 hours for both components. Extended-release formulations provide 12-hour duration. |
| Molecular Weight | Triprolidine: 278.4 Da; Pseudoephedrine: 165.23 Da |
| Action Class | Antihistamine (H1-receptor antagonist) and sympathomimetic decongestant combination |
1 tablet (2.5 mg triprolidine/60 mg pseudoephedrine) orally every 4-6 hours; max 4 tablets/24 hours.
| Dosage form | TABLET |
| Renal impairment | eGFR 30-59 mL/min: Administer every 8-12 hours; eGFR <30 mL/min: Not recommended due to accumulation risk. |
| Liver impairment | Child-Pugh A: No adjustment; Child-Pugh B or C: Contraindicated due to risk of CNS depression. |
| Pediatric use | Children 6-12 years: 0.5 tablet (1.25 mg/30 mg) orally every 4-6 hours; max 2 tablets/24 hours. Children <6 years: Not recommended. |
| Geriatric use | Start at lowest dose; consider alternative due to increased risk of anticholinergic effects, dizziness, and hypertension. Max 2 tablets/24 hours. |
| 1st trimester | Triprolidine: Limited human data; animal studies not suggestive of harm. Pseudoephedrine: Associated with gastroschisis in some studies; avoid in first trimester unless benefit outweighs risk. Use caution. |
| 2nd trimester | Triprolidine: Considered low risk based on limited data. Pseudoephedrine: May reduce uterine blood flow; use with caution. |
| 3rd trimester | Triprolidine: Avoid near term due to potential anticholinergic effects. Pseudoephedrine: Avoid in late pregnancy; may cause uterine vasoconstriction and fetal tachycardia. |
Clinical note
CNS depressants may enhance sedative effects May cause marked drowsiness and impair mental and physical abilities.
| FDA category | Animal |
| Placental transfer | Both triprolidine and pseudoephedrine cross the placenta. Pseudoephedrine is known to cross readily; triprolidine data limited but expected to cross. |
■ FDA Black Box Warning
None.
| Common Effects | Sedation |
| Serious Effects | Hypertension, Tachycardia, Arrhythmias, Seizures, Stroke, Myocardial infarction, Urinary retention, Acute angle-closure glaucoma, Severe allergic reactions (anaphylaxis) |
Severe hypertensionCoronary artery diseaseConcurrent use of MAO inhibitors (or within 14 days)Narrow-angle glaucomaUrinary retentionSevere hepatic or renal impairmentHypersensitivity to any component
| Precautions | Cardiovascular effects: Use with caution in patients with hypertension, ischemic heart disease, or arrhythmias., CNS depression: May cause drowsiness; avoid activities requiring mental alertness., Anticholinergic effects: Use with caution in patients with glaucoma, prostatic hyperplasia, or urinary retention., Drug interactions: Avoid concurrent use with MAO inhibitors or within 14 days of stopping MAO inhibitors. May interact with other sympathomimetics and antihypertensives., Pediatric use: Caution in children less than 6 years of age due to increased risk of paradoxical reactions. |
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| Breastfeeding | Triprolidine: Excreted into breast milk in small amounts; unlikely to affect infant at usual doses. Pseudoephedrine: Excreted into breast milk; may cause irritability, decreased milk production. Use caution, especially in preterm infants. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Triprolidine and pseudoephedrine are classified as FDA Pregnancy Category C. Insufficient human data exist; animal studies have shown adverse effects. First trimester: Theoretical risk of vascular disruption with pseudoephedrine; avoid if possible. Second/third trimesters: Pseudoephedrine may cause uterine artery vasoconstriction and reduced placental perfusion; avoid near term due to risk of neonatal irritability and transient hypertension. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate due to pseudoephedrine's sympathomimetic effects. Assess fetal heart rate and uterine activity if used in third trimester. Observe newborn for signs of stimulant withdrawal or irritability if used near term. |
| Fertility Effects | No well-documented effects on fertility in humans. Animal studies with pseudoephedrine suggest potential for reduced fertility at high doses. Triprolidine has no known fertility effects. |
| Food/Dietary | Avoid alcohol as it may increase sedation and dizziness. Limit caffeine intake as pseudoephedrine may cause additive stimulant effects. High-sodium foods may exacerbate fluid retention or hypertension; not a direct interaction but caution advised in hypertensive patients. |
| Clinical Pearls | Triprolidine is a first-generation antihistamine with sedative effects; pseudephedrine is a sympathomimetic decongestant. Use with caution in patients with hypertension, cardiovascular disease, hyperthyroidism, or benign prostatic hyperplasia. Avoid in patients taking MAOIs or within 14 days of discontinuation. May cause drowsiness; avoid driving or operating machinery. Central nervous system stimulation from pseudoephedrine can counteract sedation, but paradoxical drowsiness may still occur. |
| Patient Advice | Take this medication exactly as directed; do not exceed recommended dose. · May cause drowsiness; avoid alcohol and do not drive or operate heavy machinery until you know how it affects you. · If you have high blood pressure, heart disease, thyroid problems, or difficulty urinating, consult your doctor before using. · Do not use with other cold or allergy medications containing antihistamines or decongestants. · Stop use and seek medical help if you experience rapid heartbeat, tremors, insomnia, or severe dizziness. |