CETIRIZINE HYDROCHLORIDE AND PSEUDOEPHEDRINE HYDROCHLORIDE
Clinical safety rating: safe
MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.
Cetirizine is a second-generation antihistamine that selectively inhibits peripheral H1 receptors, reducing histamine-mediated allergic responses. Pseudoephedrine is a sympathomimetic amine that acts as an alpha-adrenergic agonist, causing vasoconstriction and decongestion of nasal mucosa.
| Metabolism | Cetirizine undergoes minimal hepatic metabolism via oxidation to an inactive metabolite, primarily excreted unchanged in urine. Pseudoephedrine is partially metabolized in the liver by N-demethylation to an active metabolite, with about 50-75% excreted unchanged in urine. |
| Excretion | Cetirizine: approximately 70% excreted unchanged in urine via glomerular filtration and tubular secretion; about 10% in feces. Pseudoephedrine: 70-90% excreted unchanged in urine; remainder as inactive metabolites. |
| Half-life | Cetirizine: terminal half-life ~8.3 hours in healthy adults (prolonged to 20-30 hours in renal impairment). Pseudoephedrine: terminal half-life ~4-8 hours (pH-dependent urinary excretion; prolonged in alkaline urine). |
| Protein binding | Cetirizine: 93% bound to albumin. Pseudoephedrine: not significantly protein bound (<10%). |
| Volume of Distribution | Cetirizine: 0.5-0.8 L/kg (total body water). Pseudoephedrine: 2.6-3.5 L/kg (extensive tissue distribution). |
| Bioavailability | Cetirizine: oral bioavailability ~70% (not affected by food). Pseudoephedrine: oral bioavailability ~100% (first-pass metabolism minimal). |
| Onset of Action | Oral: cetirizine onset ~1 hour; pseudoephedrine onset ~30 minutes to 1 hour. Max effects in 2-4 hours. |
| Duration of Action | Cetirizine: 24 hours (once-daily dosing). Pseudoephedrine: 12-24 hours (immediate-release: 4-6 hours; sustained-release: 12-24 hours). |
1 tablet (5 mg cetirizine / 120 mg pseudoephedrine) orally every 12 hours; maximum 2 tablets per day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-49 mL/min: 1 tablet every 24 hours. GFR <30 mL/min or dialysis: contraindicated. |
| Liver impairment | Child-Pugh A or B: no dose adjustment required. Child-Pugh C: contraindicated due to lack of data. |
| Pediatric use | Children <12 years: not approved. Children ≥12 years: same as adult dosing (5 mg/120 mg every 12 hours). |
| Geriatric use | Use with caution; start with 1 tablet every 24 hours due to increased sensitivity and risk of anticholinergic effects. |
| 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 | Small amounts excreted in breast milk. M/P ratio not established for combination. Cetirizine M/P ~0.25-1.3. Pseudoephedrine M/P ~2.6-3.5; may reduce milk production. Use with caution, especially in preterm infants. Monitor infant for irritability, sleep disturbance. |
| Teratogenic Risk | Category B: No evidence of risk in humans. Cetirizine: no increased malformations in epidemiologic studies. Pseudoephedrine: potential risk of gastroschisis in first trimester; avoid first trimester. Second/third trimester: no known fetal risks; monitor for reduced uterine blood flow due to vasoconstriction. |
■ FDA Black Box Warning
None
| Common Effects | Insomnia |
| Serious Effects |
["Hypersensitivity to cetirizine, pseudoephedrine, or any components","Severe hypertension or coronary artery disease","Use of monoamine oxidase inhibitors (MAOIs) currently or within 14 days","Narrow-angle glaucoma","Urinary retention","Severe renal impairment (CrCl <10 mL/min) for cetirizine component"]
| Precautions | ["Cardiovascular effects: Use with caution in patients with hypertension, cardiovascular disease, or ischemic heart disease due to pseudoephedrine's vasoconstrictive and positive chronotropic effects","Cerebrovascular effects: Pseudoephedrine may cause ischemic colitis, hemorrhagic stroke, or vasospasm; avoid in patients with history of stroke or vasculopathy","Nervous system effects: May cause insomnia, nervousness, or seizure; use with caution in elderly or those with seizure disorders","Renal impairment: Dose adjustment for cetirizine necessary in moderate to severe renal impairment","Drug interactions: Avoid MAO inhibitors or use within 14 days; concomitant use with other sympathomimetics may increase adverse effects"] |
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| Fetal Monitoring | Maternal: blood pressure, heart rate (due to pseudoephedrine). Fetal: ultrasound for growth restriction if used long-term; assess amniotic fluid index (rare risk of reduced placental perfusion). |
| Fertility Effects | No known significant effects on fertility in animal studies. Antihistamines may impair sperm motility in vitro; clinical relevance uncertain. |
| Food/Dietary | No significant food interactions. Avoid concurrent use of caffeine or other stimulants (e.g., coffee, tea, energy drinks) as pseudoephedrine may additive CNS stimulation. Take without regard to meals; fatty meals may delay absorption of cetirizine but not clinically relevant. |
| Clinical Pearls | Cetirizine/pseudoephedrine combines a second-generation antihistamine with a sympathomimetic decongestant. Avoid in patients with severe hypertension, coronary artery disease, or narrow-angle glaucoma. Use caution in hyperthyroidism, diabetes, and prostate hyperplasia. Monitor for CNS stimulation (insomnia, nervousness) especially in evening dosing. Cetirizine is less sedating than first-generation antihistamines but may still cause drowsiness; pseudoephedrine can counteract sedation. Contraindicated with MAOIs or within 14 days of use. Not recommended in pregnancy category B (cetirizine) but pseudoephedrine crosses placenta; avoid in lactation. |
| Patient Advice | Take this medication by mouth with or without food, with a full glass of water. · Do not crush or chew extended-release tablets; swallow whole. · Avoid alcohol, as it can increase drowsiness and side effects. · May cause drowsiness or dizziness; use caution when driving or operating machinery. · Do not exceed recommended dose; do not take more than every 12 hours. · Report rapid or irregular heartbeat, chest pain, or severe dizziness. · Discontinue use and consult doctor if symptoms persist after 7 days or with fever. · Avoid taking with other cold, allergy, or sleep aids without approval. · If you have high blood pressure, heart disease, or urinary retention, consult doctor before use. · Store at room temperature, away from moisture and heat. |