Cetirizine HCl USP
Also known as: Cetirizine HCl, Zyrtec, Aller-Tec, Reactine, Cetirizine hydrochloride (USP), CAS 83881-52-1, Cetirizine Hydrochloride
Overview
Cetirizine hydrochloride is a second-generation antihistamine used to treat allergic conditions. It is a synthetic compound and a metabolite of hydroxyzine. Primarily prescribed for allergic rhinitis, chronic urticaria, and other allergic diseases in both adults and children, cetirizine is known for its rapid onset and long duration of action. Compared to first-generation antihistamines, it carries a lower risk of sedation. Extensive clinical research supports its efficacy and safety in managing allergic symptoms. Cetirizine functions by selectively blocking H1 histamine receptors, thereby reducing the effects of histamine and alleviating allergic reactions. It is available in various forms, including tablets, syrup, and chewable tablets.
Benefits
Cetirizine is effective in improving clinical symptoms and enhancing the quality of life for individuals with allergic rhinitis. Systematic reviews indicate that its efficacy is comparable to other antihistamines and montelukast, although the certainty of evidence for clinical improvement ranges from moderate to low. Research has demonstrated that cetirizine reduces serum eosinophil cationic protein (ECP) and peripheral blood eosinophil counts, suggesting anti-inflammatory properties. It is also well-tolerated and effective in pediatric populations, with a favorable safety profile. However, studies have shown a slightly increased risk of somnolence compared to placebo, with a risk ratio of 1.62 (95% CI: 1.02–2.57).
How it works
Cetirizine works by selectively antagonizing H1 histamine receptors, which are responsible for mediating allergic responses. By blocking these receptors, cetirizine prevents histamine from binding and triggering the cascade of events that lead to allergy symptoms such as itching, sneezing, and runny nose. The drug interacts with histamine receptors in the skin, respiratory tract, and vascular endothelium, reducing inflammation and alleviating allergic reactions. Cetirizine is rapidly absorbed after oral administration, with a bioavailability of approximately 70%. Food does not significantly affect its absorption.
Side effects
Cetirizine is generally well-tolerated, but it can cause side effects in some individuals. The most common side effect is somnolence (drowsiness), particularly in children. Less common side effects include headache, dry mouth, and fatigue. Rare side effects may include allergic reactions, tachycardia, and agitation. Cetirizine may interact with other medications; for example, it can reduce gabapentin plasma concentrations by inhibiting organic cation transporters. It is contraindicated in individuals with hypersensitivity to cetirizine or hydroxyzine. Caution is advised in patients with renal impairment, and dose adjustments may be necessary. Special consideration should be given to pediatric patients, as they may be more susceptible to somnolence. It's important to consult a healthcare professional before using cetirizine, especially if you have pre-existing medical conditions or are taking other medications.
Dosage
The recommended dosage of cetirizine varies depending on age and indication. For children aged 6–12 years, the minimum effective dose is typically 5 mg per day, while adults usually require 10 mg per day. The optimal dosage range is between 5–10 mg daily, adjusted based on individual needs. The maximum safe dose is 10 mg per day for adults and 5 mg per day for children aged 6–12 years. Cetirizine is administered once daily, and the timing is not critical; it can be taken with or without food. It is available in tablets, syrup, and chewable tablets. Food does not significantly affect its absorption. No specific cofactors are required for its efficacy.
FAQs
Is cetirizine a supplement?
No, cetirizine is not a supplement but a pharmaceutical agent. It should be used under the guidance of a healthcare professional.
What are the common side effects of cetirizine?
The most common side effect is drowsiness, especially in children. Other possible side effects include headache and dry mouth.
When should I take cetirizine?
Cetirizine is taken once daily, at any time of day. It can be taken with or without food.
How quickly does cetirizine work?
Cetirizine typically reduces allergic symptoms within a few hours, and its effects can last for up to 24 hours.
Does cetirizine cure allergies?
No, cetirizine does not cure allergies. It only treats the symptoms of allergic reactions and does not prevent them.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/36090559/ – This systematic review and meta-analysis of pediatric patients with allergic rhinitis found that cetirizine improves clinical outcomes and quality of life, with similar efficacy to other antihistamines and montelukast. The study also noted that cetirizine is well-tolerated but carries an increased risk of somnolence (RR 1.62, 95% CI: 1.02–2.57). The authors noted moderate-to-low certainty evidence for some outcomes.
- https://www.ncbi.nlm.nih.gov/books/NBK549776/ – This meta-analysis focused on pediatric patients with allergic diseases and concluded that cetirizine may improve clinical outcomes, although the certainty of evidence was moderate to low. The study highlighted that cetirizine is generally well-tolerated in children. However, the analysis was limited to a pediatric population and showed some heterogeneity in the included studies.
- https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2022.940213/full – This clinical study, with a systematic review component, examined the effects of cetirizine on allergic markers. It found that cetirizine reduces serum ECP and peripheral blood eosinophil counts compared to placebo, with similar efficacy to montelukast in some measures. The study was limited by study heterogeneity and inconsistent results compared to other antihistamines in laboratory tests.
- https://accp1.onlinelibrary.wiley.com/doi/abs/10.1002/jcph.1603 – This study investigates the drug interaction between cetirizine and gabapentin. It found that cetirizine may reduce gabapentin plasma concentrations due to inhibition of organic cation transporters. This suggests a potential pharmacokinetic interaction that could affect the efficacy of gabapentin when co-administered with cetirizine.
- https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/revisions/cetirizineHydrochloride.pdf – This document provides the official standards and specifications for Cetirizine Hydrochloride USP as defined by the United States Pharmacopeia (USP). It includes information on the chemical properties, identification, assay, and other quality control tests required for cetirizine hydrochloride to meet USP standards, ensuring its purity and potency for pharmaceutical use.
