CETIRIZINE HYDROCHLORIDE HIVES
Clinical safety rating: safe
No significant drug interactions at recommended doses May cause somnolence although less than first-generation antihistamines.
Selective inverse agonist of histamine H1 receptors, blocking histamine-mediated effects in blood vessels, respiratory smooth muscle, and gastrointestinal tract.
| Metabolism | Minimally metabolized via CYP450 (CYP3A4) to an inactive metabolite; primarily excreted unchanged in urine. |
| Excretion | Approximately 70% of a dose is excreted unchanged in urine via glomerular filtration and tubular secretion, with about 10% excreted in feces. Biliary elimination is minimal. |
| Half-life | Terminal elimination half-life is approximately 8–11 hours in healthy adults (mean ~8.3 h). In renal impairment (creatinine clearance <30 mL/min), half-life may be prolonged up to 20–30 hours, requiring dose adjustment. |
| Protein binding | Approximately 93% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.5–0.8 L/kg, indicating distribution into total body water with some extravascular binding, particularly in skin and other tissues where histamine receptors are present. |
| Bioavailability | Oral bioavailability is approximately 70% (range 60–80%), with peak plasma concentrations occurring 1 hour post-dose. Food does not significantly alter absorption (Cmax reduced ~20%, AUC unchanged). |
| Onset of Action | Oral: Onset of antihistaminic effect occurs within 1 hour, with peak effect at 2–4 hours. |
| Duration of Action | Duration of action for symptom relief (e.g., urticaria) is approximately 24 hours following a single 10 mg oral dose, allowing once-daily dosing. Clinical effect may persist beyond 24 hours due to sustained receptor binding. |
10 mg orally once daily; maximum 10 mg per day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-49 mL/min: 5 mg once daily; GFR <30 mL/min or ESRD: 5 mg every other day; not recommended in ESRD. |
| Liver impairment | No dose adjustment required for Child-Pugh A or B; Child-Pugh C: 5 mg once daily. |
| Pediatric use | Age 6-12 years: 5 mg orally twice daily or 10 mg once daily; age 2-6 years: 2.5 mg orally twice daily; age 1-2 years: 2.5 mg once daily. |
| Geriatric use | Consider starting at 5 mg once daily due to decreased renal function; monitor for sedation and anticholinergic effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions at recommended doses May cause somnolence although less than first-generation antihistamines.
| FDA category | Animal |
| Breastfeeding | Present in breast milk; M/P ratio not established. Low risk to infant due to low concentrations; monitor for drowsiness, irritability. Use with caution, especially in neonates and preterm infants. |
| Teratogenic Risk | Pregnancy category B. Animal studies indicate no teratogenic effects; no adequate human studies. Fetal risk not established; use only if clearly needed. First trimester: no increased malformation risk. Second and third trimesters: theoretical risk of antihistamine-induced neonatal effects (irritability, tremors) if used near term. |
■ FDA Black Box Warning
None
| Common Effects | urticaria |
| Serious Effects |
["Hypersensitivity to cetirizine or hydroxyzine","End-stage renal disease (CrCl < 10 mL/min)","Severe hepatic impairment"]
| Precautions | ["Use with caution in patients with renal impairment (dose adjustment required for CrCl < 30 mL/min)","Avoid concurrent use with alcohol or CNS depressants","May impair driving ability"] |
| Food/Dietary | No clinically significant food interactions. However, taking with food may delay absorption slightly but does not affect overall efficacy. |
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| Fetal Monitoring | No specific monitoring required. Observe fetal heart rate and maternal vital signs if used near term. In neonates exposed late in pregnancy, monitor for sedation, poor feeding, or respiratory depression. |
| Fertility Effects | No evidence of impaired fertility in human studies. Animal studies show no adverse effects on fertility at clinically relevant doses. |
| Clinical Pearls | Cetirizine is a second-generation antihistamine with minimal anticholinergic effects. Onset of action is within 1 hour. For chronic urticaria, dosing can be increased up to 10 mg twice daily in adults if needed, but caution in renal impairment. Cetirizine is also available as an ophthalmic solution for allergic conjunctivitis. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily. · It may cause drowsiness; avoid driving or operating heavy machinery until you know how it affects you. · Do not take more than the recommended dose. · If you have kidney problems, consult your doctor for dose adjustment. · Avoid alcohol as it may increase drowsiness. |