cetirizine (Zyrtec, Zyrtec Allergy, Children's Zyrtec Allergy, Children's Zyrtec Hives Relief, PediaCare Children's 24 Hour Allergy, Aller-Tec, Wal-Zyr)
Classes: Antihistamines, 2nd Generation
Dosing and uses of Zyrtec (cetirizine)
Adult dosage forms and strengths
tablet
- 5mg
- 10mg
tablet, oral-disintegrating
- 10mg
tablet, chewable
- 5mg
- 10mg
syrup
- 5mg/5mL
solution
- 5mg/5mL
Allergies/Hay Fever/Urticaria
Perennial and seasonal allergic and vasomotor rhinitis; relief of symptoms from colds, urticaria, angioedema, anaphylactic reactions, pruritus, allergic conjunctivitis
5-10 mg PO qDay, depending on severity of symptoms; not to exceed 10 mg qDay
Dosing Modifications
Renal impairment
- GFR >50 mL/min: Dose adjustment not necessary
- GFR ≤ 50 mL/min: 5 mg PO qDay
- Peritoneal dialysis: 5 mg PO qDay
- Intermittent hemodialysis: 5 mg PO qDay; may also administer 3 times weekly
Hepatic impairment
- Dose adjustment not provided by manufacturer's label
Administration
May be taken with or without food
Pediatric dosage forms and strengths
tablet
- 5mg
- 10mg
tablet, oral-disintegrating
- 10mg
tablet, chewable
- 5mg
- 10mg
syrup
- 5mg/5mL
solution
- 5mg/5mL
Allergies/Hay Fever/Urticaria
Perennial and seasonal allergic and vasomotor rhinitis
<2 years: Safety and efficacy not established
2-6 years: 2.5 mg (0.5 teaspoon) oral solution PO qDay; can increase to 5 mg PO qDay or 2.5 mg PO twice daily; not to exceed 5 mg qDay
>6 years: 5-10 mg PO qDay, depending on severity of symptoms; not to exceed 10 mg qDay
Dosing Modifications
Renal impairment
- GFR ≥30 mL/min/1.73 m²: Dose adjustment not necessary
- GFR 10-29 mL/min/1.73 m²: Decrease dose by 50%
- GFR < 10 mL/min/1.73 m²: Not recommended
- Intermittent hemodialysis or peritoneal dialysis: Decrease dose by 50%
Hepatic impairment
- Dose adjustment not provided by manufacturer's label
Administration
May be taken with or without food
Geriatric dosage forms and strengths
5 mg PO qDay; may increase to 10 mg/day mazimum, depending on severity of symptoms; not to exceed 5 mg qDay in patients >77 years
Zyrtec (cetirizine) adverse (side) effects
>10%
Somnolence (2-14%)
Headache (11-14%)
1-10%
Fatigue (5.9%)
Dry mouth (5%)
Dizziness (2%)
Diarrhea (2-3%)
Malaise (4%)
Bronchospasm (2-3%)
Vomiting (2-3%)
Epistaxis (2-4%)
<1%
Stomach pain
Drowsiness
Angioedema
Fussiness
Hallucinations
Hypotension
Tremor
Tongue discoloration
Warnings
Contraindications
Documented hypersensitivity to cetirizine, hydroxyzine
Cautions
Avoid alcohol, sedatives, and tranquilizers, due to increased risk of drowsiness
May cause CNS depression; avoid activities requiring mental alertness until accustomed to medication
Use caution in hepatic and renal impairment
The elderly may be more sensitive to adverse effects
Pregnancy and lactation
Pregnancy category: B; C for Zyrtec-D 12 Hour
Lactation: Excreted in breast milk; use not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Zyrtec (cetirizine)
Mechanism of action
Histamine H1-receptor antagonist; competes with histamine on effector cells in the gastrointestinal tract, blood vessels and respiratory tract
Absorption
Peak plasma concentration: 114 ng/mL
Peak serum time: 1 hr
Duration: >24 hr ( suppression of skin wheal and flare reactions
Distribution
Protein bound: 93%
Vd: 0.56 L/kg
Metabolism
Metabolism: Liver; low first pass
Limited extent by oxidative O-dealkylation to inactive metabolite
Elimination
Half-life: 7.9hr
Excretion: Urine (70%); feces (10%)
