Cetirizine; Uses, Dosage, Side Effects, Drug Interactions

Cetirizine; Uses, Dosage, Side Effects, Drug Interactions

Cetirizine is a potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Unlike many traditional antihistamines, it does not cause drowsiness or anticholinergic side effects.
Cetirizine is a metabolite of hydroxyzine and a selective peripheral histamine H1-receptor antagonist. It is used for symptomatic treatment of seasonal and perennial allergic rhinitis and for chronic urticaria.
Cetirizine and its enantiomer levocetirizine are second-generation antihistamines that are used for the treatment of allergic rhinitis, angioedema, and chronic urticaria. Cetirizine and levocetirizine have been linked to rare, isolated instances of clinically apparent acute liver injury.

Cetirizine is a potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Unlike many traditional antihistamines, it does not cause drowsiness or anticholinergic side effects. Second-generation antihistamines like cetirizine are less able to cross the blood-brain barrier and therefore have diminished effects on the central nervous system compared to first-generation drugs. As such, they are less likely to cause drowsiness or memory impairment.

Mechanism of action of Cetirizine

Cetirizine competes with histamine for binding at H1-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The low incidence of sedation can be attributed to reduced penetration of cetirizine into the CNS as a result of the less lipophilic carboxyl group on the ethylamine side chain.Cetirizine acts as a highly selective antagonist of the histamine H1 receptor.The Ki values for the H1 receptor are approximately 6 nM for cetirizine, 3 nM for levocetirizine, and 100 nM for dextrocetirizine, indicating that the levorotatory enantiomer is the main active form. Cetirizine has 600-fold or greater selectivity for the H1 receptor over a wide variety of other sites, including muscarinic acetylcholine, serotonin, dopamine, and α-adrenergic receptors among many others.The drug shows 20,000-fold or greater selectivity for the H1 receptor over the five muscarinic acetylcholine receptors and hence does not exhibit anticholinergic effects. It shows negligible inhibition of the hERG channel (IC50 > 30 µM)and no cardiotoxicity has been observed with cetirizine at doses of up to 60 mg/day, six times the normal recommended dose and the highest dose of cetirizine that has been studied in healthy subjects.

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Indications of Cetirizine

  • Chronic Idiopathic Urticaria
  • Perennial Allergic Rhinitis (PAR)
  • Pollen Allergy
  • Sneezing
  • Runny nose
  • Itchy or watery eyes
  • Itchy throat or nose
  • Upper respiratory tract hypersensitivity reaction, site unspecified
  • Rhinorrhea
  • Postnasal discharge,
  • Nasal pruritus,
  • Ocular pruritus &tearing
  • Cetirizine is indicated for the relief of nasal and ocular symptoms of seasonal and perennial allergic rhinitis.
  • Cetirizine is indicated for the relief of symptoms of chronic idio
  • For the relief of symptoms associated with seasonal allergic rhinitis, perennial allergic rhinitis and the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria

Contra-Indications of Cetirizine

  • Increased Pressure in eyes
  • Liver problems
  • Kidney disease with a reduction in kidney function
  • Cannot Empty Bladder
Allergies
  • Antihistamines
  • Antihistamines – Piperazine

Dosage of Cetirizine

Strengths: 10 mg; 5 mg; 1 mg/mL

Children aged 6 to 12 years

The recommended dose is 5 mg twice daily as half a tablet twice a day.

Adults and children aged 12 years and over

The recommended dose is 10 mg once daily as one tablet.

Allergic Rhinitis

  • 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Urticaria

  • 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Pediatric Dose

Allergic Rhinitis

6 months to 2 years

  • Initial dose: 2.5 mg orally once a day
  • Maintenance dose: 2.5 mg orally once to 2 times a day
  • Maximum dose: 5 mg/day

2 to 5 years

  • Initial dose: 2.5 mg orally once a day
  • Maintenance dose: 2.5 mg orally 2 times a day OR 5 mg orally once a day
  • Maximum dose: 5 mg/day
  • 6 years and older: 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Urticaria

6 months to 2 years

  • Initial dose: 2.5 mg orally once a day
  • Maintenance dose: 2.5 mg orally once to 2 times a day
  • Maximum dose: 5 mg/day

2 to 5 years

  • Initial dose: 2.5 mg orally once a day
  • Maintenance dose: 2.5 mg orally 2 times a day OR 5 mg orally once a day
  • Maximum dose: 5 mg/day
  • 6 years and older: 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day
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Side Effects of Cetirizine

The most common

More common

Less common

Drug Interactions of Cetirizine

Cetirizine may interact with following drugs,supplements & may change the efficacy of drugs

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Pregnancy & Lactation of Cetirizine

FDA Pregnancy Category C

Pregnancy

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

It is not known if cetirizine passes into breast milk. If you are a breastfeeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding.

References

 

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