CETIRIZINE HYDROCHLORIDE HIVES RELIEF
Clinical safety rating: safe
No significant drug interactions at recommended doses May cause somnolence although less than first-generation antihistamines.
Selective peripheral H1-receptor antagonist. Competitively inhibits histamine at the H1 receptor, preventing histamine-mediated symptoms such as pruritus, sneezing, and rhinorrhea.
| Metabolism | Minimally metabolized in the liver via oxidative pathways (O-dealkylation). Primarily excreted unchanged in urine. CYP3A4 involvement is minor. |
| Excretion | Approximately 70% of the dose is excreted unchanged in urine via glomerular filtration and tubular secretion; 10% is excreted in feces. Biliary excretion is minimal. |
| Half-life | Terminal elimination half-life is approximately 8-11 hours in healthy adults; increases to approximately 20 hours in renal impairment (CrCl <40 mL/min). |
| Protein binding | Approximately 93% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Apparent volume of distribution (Vd) is 0.5-0.8 L/kg, indicating distribution into total body water. |
| Bioavailability | Oral bioavailability is approximately 70% (range 60-80%). |
| Onset of Action | Oral: 1 hour for inhibition of histamine-induced wheal and flare; peak effect at 4-8 hours. |
| Duration of Action | Duration of antihistamine effect is approximately 24 hours, allowing once-daily dosing; wheal and flare suppression persists for >24 hours. |
| Molecular Weight | 461.82 |
| Action Class | Second-generation antihistamine (piperazine derivative) |
Oral, 10 mg once daily; may be increased to 10 mg twice daily if needed.
| 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 | Child-Pugh A: no adjustment; Child-Pugh B or C: 5 mg once daily. |
| Pediatric use | Children 6-23 months: 2.5 mg (2.5 mL) once daily; 2-5 years: 2.5 mg (2.5 mL) once daily, may increase to 2.5 mg twice daily; 6-11 years: 5 mg (5 mL) once daily; ≥12 years: same as adult. |
| Geriatric use | No specific adjustment unless renal impairment; consider starting at 5 mg once daily in patients >77 years due to decreased clearance. |
| 1st trimester | Limited human data; animal studies show no teratogenicity at clinically relevant doses. Generally considered low risk, but avoid unnecessary use. |
| 2nd trimester | Safe for use if clinically indicated; no known fetal harm. |
| 3rd trimester | Safe for use; no known risk of neonatal adverse effects. |
Clinical note
No significant drug interactions at recommended doses May cause somnolence although less than first-generation antihistamines.
| FDA category | Animal |
| Placental transfer | Placental transfer occurs; animal studies indicate minimal transfer. Human data limited. |
| Breastfeeding | Excreted into breast milk in low amounts (estimated relative infant dose ~0.6-1.1% of maternal weight-adjusted dose). No adverse effects reported in breastfed infants. Use caution in premature neonates or those with renal impairment due to potential accumulation. |
■ FDA Black Box Warning
None.
| Common Effects | urticaria |
| Serious Effects | Anaphylaxis, Angioedema, Severe hypotension, Seizures, Urinary retention, Hepatotoxicity (rare) |
Hypersensitivity to cetirizine or any piperazine derivativeSevere renal impairment (CrCl <10 mL/min) for oral solution form due to excipients
| Precautions | Somnolence and sedation may occur; caution when driving or operating machinery., Renal impairment: dose adjustment required for CrCl < 31 mL/min., Avoid concurrent use of alcohol or CNS depressants., Use with caution in patients with urinary retention or prostatic hypertrophy due to anticholinergic effects. |
| Food/Dietary | Food does not affect absorption; can be taken with or without meals. Avoid concurrent grapefruit juice (may increase cetirizine levels). |
Loading safety data…
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies no fetal harm. Limited human data: no increased malformations. Avoid first trimester if possible. |
| Fetal Monitoring | No specific monitoring required. Observe for maternal CNS depression. |
| Fertility Effects | No known adverse effects on fertility. |
| Clinical Pearls | Cetirizine is a second-generation antihistamine with minimal anticholinergic effects. For urticaria, it may be more effective than loratadine. Onset within 1 hour, duration 24 hours. Dose adjustment needed in renal impairment (CrCl <30 mL/min: 5 mg daily). |
| Patient Advice | Take once daily; do not exceed recommended dose. · May cause drowsiness; avoid driving if affected. · Do not take with alcohol or other CNS depressants. · Use caution in elderly due to increased fall risk. · If symptoms persist beyond 6 weeks, consult prescriber. |