Cetirizine dihydrochloride

Cetirizine hydrochloride(83881-52-1) is an orally-active and selective histamine (H1)-receptor antagonist. It is a second-generation antihistamine and a human metabolite of hydroxyzine. Three important features of cetirizine are: a high specificity fort he H1-receptor; a low need for metabolism, and the existence of non-H1-dependent activities on cells involved in the pathogenesis of allergy.
Cetirizine is used to treat seasonal allergic rhinitis (SAR), perennial allergic rhinitis, useful in treating urticaria and atopic dermatitis. Cetirizine possesses also mild anti-inflammatory effects.

[1] E. J. Corey and Christopher J. Helal, Catalytic Enantioselective Synthesis of the Second-Generation Histamine Antagonist Cetirizine Hydrochloride, Tetrahedron Letters, 1996, vol. 37, 4837-4840
[2] Jay M. Portnoy and Chitra Dinakar, Review of cetirizine hydrochloride for the treatment of allergic disorders, Journal of Expert Opinion on Pharmacotherapy, 2004, vol. 5, 125-135

Cetirizine hydrochloride is a once-daily, non-sedating antihistamine useful in the treatment of allergic rhinitis, urticaria and conjunctivitis. It is reported to be more effective than most other agents in this category such as terfenadine and astemizole.

Cetirizine Hydrochloride occurs as a white crystalline powder or crystalline solid. It is very soluble in water, and slightly soluble in ethanol (99.5). It dissolves in 0.1 mol/L hydrochloric acid TS. A solution of Cetirizine Hydrochloride (1 in 10) shows no optical rotation.

UCB (Belgium)

Cetirizine Hydrochloride may be used as a pharmaceutical reference standard for the determination of the analyte in pharmaceutical formulations by various chromatography techniques.

Cetirizine hydrochloride is a nonsedating type histamine H1-receptor antagonist. A major metabolite of Hydroxyzine. Pharmacological activity resides primarily in the (R)-isomer. It is Cetirizine is an antihistamine medicine 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.

ChEBI: Cetirizine hydrochloride is a diarylmethane.

Cetirizine HCl (Zyrtec) is the carboxylic acid metabolite of hydroxyzine. It is a selective, peripheral H1 receptor antagonist. It is a long-lasting antihistamine. It does not appear to have the same adverse cardiac effects as the other nonsedating H1 antihistamines; however, additional data are required. Indicated for allergic rhinitis and chronic urticaria.

Preparation of 2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]- ethoxy]acetic acid (cetirizine).
To a mixture of 50 g 2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]- ethanol and 225 ml of tert-butanol at 45°C under a nitrogen was added 21 g tert-BuOK. The temperature was raised to 75-80°C and the mixture was kept at this temperature. After 45 min was added 11 g sodium chloracetate; after 1.5 hour was added 5.2 g tert-BuOK; after 2 hours was added 5.64 g sodium chloracetate; after 2.5 hours was added 1.9 g tert-BuOK; after 3 hours was added 1.9 g sodium chloracetate; after 3.5 hours was added 0.8 g tert-BuOK; and after 4 hours was added 1.13 g sodium chloracetate. Then about 150 ml tert-butanol was distilled of, 190 ml of water was added and the distillation of tert-butanol was continued until the temperature of the vapour reaches 100°C. To the reaction mixture was added 60 ml of water and 8 ml concentrated hydrochloric acid to pH 8. Unreacted 2-[4-[(4-chlorophenyl) phenylmethyl]-1-piperazinyl]-ethanol was extracted with diethyl ether. The aqueous phase was acidified to pH 5 by addition of hydrochloric acid and extracted with dichloromethane (200 ml x 3). The extract was dried over MgSO4, filtered and concentrated in a rotary evaporator. An obtained oil was allowed to crystallize by addition of 150 ml of 2-butanone, yields of 2-[4-[(4- chlorophenyl)phenylmethyl]-1-piperazinyl]-ethoxy]acetic acid 55.5%, M.P. 146-148°C.
32.7 g 2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]-ethoxy]acetic acid was suspended in a mixture of 125 ml of water and 13.8 ml 37% aqueous hydrochloric acid. The mixture was concentrated in a rotary evaporator. An obtained oil was allowed to crystallize by addition of 245 ml of 2-butanone, yields of 2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]-ethoxy]acetic acid dihydrochloride 88%, M.P. 228.22°C.

Zyrtec (Pfizer).

Antihistaminic; Antiallergic

Cetirizine hydrochloride, a second generation antihistaminic drug, is one of the carboxylated metabolites of hydroxyzine that can typically bind to histamine H₁ receptor. It is effective against diseases such as urticaria, angioedema, allergies and hay fever.

Histamine H 1 receptor antagonist that displays selectivity over other receptors at concentrations up to 10 μ M. A non-sedating antihistamine that inhibits histamine release and eosinophil chemotaxis during secondary phase allergic response. Inhibits activation of eosinophils, neutrophils and monocytes in vivo .

Cetirizine hydrochloride is an orally active and selective H1-receptor antagonist. Antihistaminic; Piperazines. Non-sedating type histamine H1-receptor antagonist; major metabolite of hydroxyzine. Pharmacological activity resides primarily in the (R)-isomer.

There are many side effects of Cetirizine hydrochloride which can be classified into five levels including common side effects (10%), more common side effects (1%), rare side effects (0.1%), very rare side effects (0.01%) and other side effects.
Common side effects include: drowsiness, dizziness, headache, pharyngitis, rhinitis (children), diarrhoea (children), nausea, dry mouth, fatigue. More common side effects include: restlessness, paresthesia (tingling or numbness in the hands and feet), diarrhoea, stomach pain, pruritus (itching), rash, asthenia (unusual weakness), weakness.
Rare side effects include: hypersensitivity, aggression, confusion, depression, hallucinations, insomnia, convulsions, tachycardia (fast heartbeat), abnormal liver function, hives, oedema (swelling), weight gain. Very rare side effects: Thrombocytopenia (low platelet count), anaphylaxis, convulsions (uncontrolled body movements), gustatory disturbances (disturbances in taste or loss of taste), dyskinesia (dyskinesia (uncontrolled movements), dystonia (uncontrolled muscle spasms), syncope (fainting), ophthalmoplegia (uncontrolled circular movements of the eyes), angioedema (severe). allergic reaction that causes swelling of the face or throat), dysuria (pain when urinating), incontinence (bedwetting).
Other side effects include: increased appetite, suicidal thoughts, nightmares, amnesia, memory problems, dizziness (spinning sensation), inflammation of the liver, urinary retention (difficulty in urinating), pain in the joints, rash with pus-containing blisters, and severe itching after stopping the drug (pruritus).

Cetirizine is a H1 receptor blocking antihistamine agent that may be useful for the adjunctive treatment of histamine-mediated pruritic conditions in dogs or cats.

Potentially hazardous interactions with other drugs
Antivirals: concentration possibly increased by ritonavir.

Cetirizine does not undergo extensive first pass metabolism.
About two thirds of the dose is excreted unchanged in urine.

5 to 10mg daily.