API Cetirizine hydrochloride

Name	Cetirizine hydrochloride
CAS number	83881-52-1
Synonym	Cetirizine Hydrochloride; 83881-52-1; Reactine; Zyrtec; CETIRIZINE HYDROCHLORIDE; Alerlisin; Aliud Brand of Cetirizine Dihydrochloride; Alpharma Brand of Cetirizine Dihydrochloride; AWD.pharma Brand of Cetirizine Dihydrochloride; Azupharma Brand of Cetirizine Dihydrochloride; Basics Brand of Cetirizine Dihydrochloride;
Related CAS	83881-51-0 (free base)   83881-52-1 (HCl)
Description	Cetirizine hydrochloride is a potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Cetirizine hydrochloride is a carboxylated metabolite of hydroxyzine that acts as a selective Histamine H1 receptor inverse agonist. Compared to its parent compound, it shows similar antihistaminic activity, but with greater H1 selectivity and less sedative effects.
Structure
Molecular Formula	C21H27Cl3N2O3
Molecular Weight	461.810
Appearance	Solid powder
Quality Standard	USP, EP, BP, CP
Shipping Condition	Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.
Storage Condition	Dry, dark and at 0 – 4 ℃ for short term (days to weeks) or -20 ℃ for long term (months to years).
Shelf Life	>2 years if stored properly
Sample package	Aluminium foil bag
Commercial package	Aluminium Tin, Fiber drum
Origin	China

Cetirizine Hydrochloride More Info

Definition and Chemical Structure

Cetirizine hydrochloride is a second - generation antihistamine. Chemically, it is a piperazine derivative. Its chemical formula is C₂₁H₂₅ClN₂O₃·2HCl. The molecular structure of cetirizine hydrochloride allows it to effectively interact with histamine receptors in the body.

Mechanism of Action

It works by selectively blocking the H₁ - histamine receptors. Histamine is a chemical mediator that is released during allergic reactions and causes symptoms such as itching, sneezing, runny nose, and watery eyes. By binding to the H₁ - receptors, cetirizine hydrochloride prevents the action of histamine, thereby reducing these allergic symptoms.

Pharmacokinetics

Absorption: It is well - absorbed from the gastrointestinal tract after oral administration. Peak plasma concentrations are usually reached within 1 - 1.5 hours.

Distribution: It is widely distributed throughout the body and has a volume of distribution that indicates its presence in various tissues. It can cross the blood - brain barrier to some extent, but compared to first - generation antihistamines, it has a much lower propensity to cause central nervous system (CNS) side effects such as drowsiness.

Metabolism and Excretion: A significant portion of cetirizine hydrochloride is excreted unchanged in the urine. The rest is metabolized in the liver, mainly through oxidation. The drug has a half - life of about 7 - 10 hours, which means it remains in the body for a relatively long time to provide continuous anti - allergic effects.

Medical Uses

Allergic Rhinitis: It is commonly used to relieve the symptoms of allergic rhinitis, such as nasal congestion, sneezing, and itchy nose. For example, in patients who are allergic to pollen, taking cetirizine hydrochloride can significantly reduce the frequency and severity of sneezing attacks during the pollen season.

Urticaria: It is effective in treating acute and chronic urticaria. The itching and wheals associated with urticaria can be alleviated. For instance, a patient with chronic urticaria who experiences itchy rashes on a daily basis may find relief after taking cetirizine hydrochloride regularly.

Atopic Dermatitis: It can also be used as an adjunct treatment for atopic dermatitis to relieve the itching component of the condition and improve the patient's quality of life.

Side Effects and Precautions

Common Side Effects: Mild side effects may include drowsiness (although much less than first - generation antihistamines), dry mouth, headache, and fatigue. These side effects usually do not require discontinuation of the drug and tend to be self - limiting.

Precautions: It should be used with caution in patients with impaired renal function, as the drug's excretion may be affected. Pregnant and lactating women should consult a doctor before use, as the safety of the drug in these populations requires further evaluation. Additionally, it may interact with other medications, such as CNS - depressant drugs, so it's important to inform the doctor of all medications being taken.