Cetirizine

Cetirizine 3d.MOL

General

Cetirizine, with the chemical name (±) - [2- [4- [ (4-chlorophenyl)phenylmethyl] -1- piperazinyl] ethoxy]acetic acid dihydrochloride,a major matabolite of Hydroxyzine,which is an orally active and selective H1-receptor antagonist. The chemical structure is shown below:

This chemical compound is a white, crystalline powder and is water soluble, it is mainly used in medical treatment of allergies, hay fever, angioedema, and urticaria. ZYRTEC tablets(the active component of the chemical compound)are formulated as white, film-coated, rounded-off rectangular shaped tablets for oral administration and are available in 5 and 10 mg strengths.

Synthesis

(S)-cetirizine.2HCl is prepared via the diastereoselective organometallic addition to N-tert-butanesulfnyl adlimines (scheme 1). Organometallic reagent addition to imines is advantageous in that either enantiomeric forms of ceterizine (structure 2) can be produced by changing the imine/ organometallic partner; the imine of 4-chlorobenzaleldehyde (structure 4) with metallobenzene gives the opposite enantiomer to the reaction of benzaldehyde imine (structure 3) with the 4-chlorometallobenzene.

Spectra

NMR Spectral information showing a variation of chemical shifts against pD; these pD values are obtained when a correction of 0.4 were added to measured pH values[1]

¹H-NMR spectra

¹³C-NMR spectra for the ¹³C nuclei in D₂ nuclei at 24.85 C and 200 MHz.

Pharmaceutical Usage

Usages of ZYRTEC

Preparations

Seasonal Allergic Rhinitis

Symptoms: Zyrtec provides relief to symptoms of sneezing, rhinorrhea, nasal prutitus, ocular pruritus, tearing, and redness of the eyes

Allergens: ragweed, grass and tree pollens are causes of seasonal allergic rhinitis

Perennial Allergic Rhinitis:

Symptoms: sneezing, rhinorrhea, postnasal discharge, nasal pruritus, ocular pruritus, and tearing.

Allergens: dust mites, animal dander and molds

Chronic Urticaria:

Symptoms: uncomplicated skin

Allergens: hives

DOSING: Cetirizine should be taken at doses specifically directed by a physician, it can be taken with food.

DRUG INTERACTIONS: Cetirizine should be taken only in doses prescribed. Increasing the dose can be dangerous. When taking cetirizine with theophylline the dose of theophylline may need to be reduced. Cetirizine occasionally can cause sleepiness . Cetirizine can be taken with erythromycin or ketaconazole without the increased risk of heart irregularities common to other non-sedating antihistamines. Cetirizine also can be used to treat children. SIDE EFFECTS: Sleepiness occurs in 14% of patients. Dry mouth, nausea, headache, fatigue, jitteriness and sore throat are infrequently reported with cetirizine. |-

References

Cetirizine
General
Systematic name	(±) - [2- [4- [ (4-chlorophenyl)phenylmethyl] -1- piperazinyl] ethoxy]acetic acid dihydrochloride
Molecular formula	C21H25ClN2O3
SMILES	C1CN(CCN1CCOCC(=O)O)C(C2=CC=CC=C2)C3=CC=C(C=C3)Cl
Molar mass	461.82g/mol
Percentage composition	C 64.86%, H 6.48%, Cl 9.12%, N 7.20%, O 12.34%
Appearance	White Crystalline powder, water soluble
CAS number	83881-51-0
[1]	Alatrol, Cetirizina MERCK, Cetzine Glaxo, Cetirizin, Humex, Letizen, Razene, Reactine, Zyrtec, Zirtec, Zodac, Zirtek, Zynor, Zyrlek
Boiling point
Melting point	110-115°(for crystals from ethanol)
Refractive index
[2]	Well absorbed
[3]	93% avg
Lawson Number	28000, 14305, 3122, 1771
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas