خواص دارویی و گیاهی
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(Cetirizine hydrochloride)
Read all of this leaflet carefully because it contains important information for you.
This medicine is available without prescription. However, you still need to use Cetirizine 10 mg
Tablets carefully to get the best results from it.
In this leaflet:
قرص cetirizine 10
Cetirizine hydrochloride is the active ingredient
of Cetirizine 10 mg Tablets.
Cetirizine 10 mg Tablets is an antiallergic
medication.
In adults and children aged 6 year and above,
Cetirizine 10 mg Tablets are indicated
Do not take Cetirizine 10 mg Tablets
You should not take Cetirizine 10 mg Tablets:
Take special care with Cetirizine 10 mg Tablets
If you have kidney problems, please ask your
doctor for advice; if necessary, you may have to
take a lower dose. The new dose will be
determined by your doctor.
If you are an epileptic patient or a patient at risk
of convulsions, you should ask your doctor for
advice.
Taking other medicines
Please tell your doctor or pharmacist if you are
taking or have recently taken any other medicines,
including medicines obtained without a
prescription.
Due to the profile of cetirizine, no interactions with
other drugs are expected.
Taking Cetirizine 10 mg Tablets with food and
drink
Food does not noticeably affect the absorption of
cetirizine.
No interactions having a noticeable impact have
been observed between alcohol (at the blood
level of 0.5 per millilitre corresponding to one
glass of wine) and cetirizine used at the normal
doses. However, as it is the case with all
antihistamines, it is recommended to avoid
consumption of alcohol while taking this medicine.
Pregnancy and breast-feeding
Ask your doctor for advice before taking any
medicine.
As with other drugs, use of Cetirizine 10 mg
Tablets should be avoided by pregnant women.
Accidental use of the drug by a pregnant woman
should not produce any harmful effects on the
foetus. Nevertheless, the administration of the
medicine should be discontinued.
You should not take Cetirizine 10 mg Tablets
during breast-feeding because cetirizine passes
into breast milk.
Driving and using machines
Clinical studies have produced no evidence of
impaired attention, alertness and driving
capabilities after taking Cetirizine 10 mg Tablets
at the recommended dose.
If you intend to drive, operate machinery, or
perform other tasks that need your full attention,
you should not exceed the recommended dose
and you should closely observe your response
to the drug.If you are a sensitive patient, you may
find that the simultaneous use of alcohol or other
nervous depressant agents may additionally affect
your attention and ability to react.
Important information about some of the
ingredients of Cetirizine 10 mg Tablets
Cetirizine 10 mg Tablets contain lactose; if you
have been told by your doctor that you have an
intolerance to some sugars, please contact your
doctor before taking this medicinal product.
Allergy skin test
If you are going to have an allergy skin test stop
taking Cetirizine 10 mg Tablets for three days
before the test.
How and when should you take Cetirizine 10
mg Tablets?
These guidelines apply unless your doctor has
given you different instructions on how to use
Cetirizine 10 mg Tablets.
Please follow these instructions, otherwise Cetirizine
10 mg Tablets may not be fully effective.
Tablets need to be swallowed with a glass of
liquid.
Adults and adolescents above 12 years old:
10 mg once daily as one tablet.
Children between 6 and 12 years old:
5 mg twice daily as half a tablet.
Patients with kidney problems:
Patients with moderate renal impairment are
recommended to take 5 mg once daily as a half
tablet.
قرص cetirizine 10
If you feel that the effect of Cetirizine 10 mg
Tablets is too weak or too strong, please consult
your doctor.
If you take more Cetirizine 10 mg Tablets than
you should
If you think you have taken an overdose of
Cetirizine 10 mg Tablets, please inform your doctor.
Your doctor will then decide what measures, if any,
should be taken.
After an overdose, the side effects described
below may occur with increased intensity. Adverse
effects such as confusion, diarrhoea, dizziness,
tiredness, headache, ailing, dilating (widening)
of the pupil, itching, restlessness, sedation,
somnolence, stupor, abnormal rapid heart rate,
tremors and urinary retention have been reported.
If you forget to take Cetirizine 10 mg Tablets
If you forget to take a tablet, take it as soon as
you remember, but wait at least 24 hours before
taking the next tablet. Do not take a double dose
to make up for a forgotten dose.
If you stop taking Cetirizine 10 mg Tablets
If you have any further questions on the use of
this product, ask your doctor or pharmacist.
Like all medicines, Cetirizine 10 mg Tablets can
cause side effects, although not everybody gets
them.
The following side effects have been reported in
post marketing experience. The frequencies are
defined as such: (common: 1 patient out of 100
to less than 1 out of 10, uncommon: 1 out of
1,000 to less than 1 out of 100, rare: 1 out of
10,000 to less than 1 out of 1,000, very rare: less
than 1 out of 10,000, not known: cannot be
estimated from the available data).
If you develop one of the side effects
described above, please inform your doctor.
At the first signs of an allergic
(hypersensitivity) reaction, stop taking
Cetirizine 10 mg Tablets and contact your
doctor immediately. Symptoms of an allergic
(hypersensitivity) reaction include difficulty
breathing, swelling of the face, neck, tongue
or throat. Your doctor will then assess the
severity and decide on any further measures
that may be necessary.
If you think you have any side effects not
mentioned in this leaflet, please inform your
doctor or pharmacist.
Keep out of the reach and sight of children.
Do not use Cetirizine 10 mg Tablets after the
expiry date which is stated on the box and blister.
This medicine does not require any special
storage conditions.
What Cetirizine 10 mg Tablets contain
What Cetirizine 10 mg Tablets look like and
contents of the pack
White, capsule shaped film-coated tablets with
a score on one side.
There are 7, 10 or 30 tablets in a pack.
Not all pack sizes may be marketed.
Marketing Authorization Holder and
Manufacturer:
Dexcel®-Pharma Ltd., 7 Sopwith Way, Drayton
Fields, Daventry, Northamptonshire, NN11 8PB,
UK.
This leaflet was last revised in May 2012.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Medical Disclaimer
Use these dosage charts for infants and children under 12 years old:
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Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. Data sources include IBM Watson Micromedex (updated 1 July 2019), Cerner Multum™ (updated 1 July 2019), Wolters Kluwer™ (updated 29 June 2019) and others.
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Generic Name: cetirizine (se TIR a zeen)Brand Names: Zyrtec
Medically reviewed by Drugs.com. Last updated on Dec 12, 2018.
Cetirizine is an antihistamine that reduces the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. It is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose.
Cetirizine is also used to treat itching and swelling caused by hives.
Cetirizine may also be used for other purposes not listed in this medication guide.
قرص cetirizine 10
Before taking cetirizine, tell your doctor about all of your medical conditions.
Older adults may need to take a lower than normal dose. Follow your doctor’s instructions.
Take cetirizine exactly as directed on the label, or as prescribed by your doctor. Do not use it in larger amounts or for longer than recommended.
You may take cetirizine with or without food.
The chewable tablet must be chewed before you swallow it.
Measure liquid medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.
Cetirizine dosage information (in more detail)
Take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose. Do not take extra medicine to make up the missed dose.
Overdose symptoms may include feeling restless or nervous, and then feeling drowsy.
fast, pounding, or uneven heartbeat;
weakness, tremors (uncontrolled shaking), or sleep problems (insomnia);
severe restless feeling, hyperactivity;
confusion;
problems with vision; or
urinating less than usual or not at all.
Less serious side effects may include:
dizziness, drowsiness;
tired feeling;
dry mouth;
sore throat, cough;
nausea, constipation; or
headache.
This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.
Cetirizine side effects (in more detail)
There may be other drugs that can interact with cetirizine. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.
Cetirizine drug interactions (in more detail)
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use cetirizine only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Medical Disclaimer
Other brands: Zyrtec
Use these dosage charts for infants and children under 12 years old:
prednisone, loratadine, montelukast, Zyrtec, Benadryl, promethazine, diphenhydramine, Xolair
Cetirizine reviews
The easiest way to lookup drug information, identify pills, check interactions and set up your own personal medication records. Available for Android and iOS devices.
Subscribe to Drugs.com newsletters for the latest medication news, alerts, new drug approvals and more.
قرص cetirizine 10
Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. Data sources include IBM Watson Micromedex (updated 1 July 2019), Cerner Multum™ (updated 1 July 2019), Wolters Kluwer™ (updated 29 June 2019) and others.
Third Party Advertising
We comply with the HONcode standard for trustworthy health information – verify here
Copyright © 2000-2019 Drugs.com. All rights reserved.
Cetirizine, also commonly known as Zyrtec, is an orally active second-generation histamine H1 antagonist proven effective in the treatment of various allergic symptoms, such as sneezing, coughing, nasal congestion, hives, and other symptoms 1, 2.
One of the most common uses for this drug is for a condition called allergic rhinitis. The prevalence of allergic rhinitis in the United States is about 15% according to physician diagnoses, and up to 30%, according to self-reported nasal symptoms. Allergic rhinitis is associated with multiple missed or unproductive days at work and school, problems with sleep, and other difficulties with day to day activities for many individuals 3. Furthermore, some antihistamine agents that are used to treat this condition cause undesirable, sedating effects 4.
Cetirizine is one of the first second-generation H1 antihistamines (SGAHs)formulated to selectively inhibit the H1 receptor without sedating effects 2.
A unique ID assigned by the FDA when a product is submitted for approval by the labeller.
A governmentally-recognized ID which uniquely identifies the product within its regulatory market.
قرص cetirizine 10
A unique ID assigned by the FDA when a product is submitted for approval by the labeller.
A governmentally-recognized ID which uniquely identifies the product within its regulatory market.
A unique ID assigned by the FDA when a product is submitted for approval by the labeller.
A governmentally-recognized ID which uniquely identifies the product within its regulatory market.
Seasonal Allergic Rhinitis: Indicated for the relief of symptoms associated with seasonal allergic rhinitis caused by allergens such as ragweed, grass and tree pollens in adults and children 2 years of age and above. Symptoms treated effectively include sneezing, rhinorrhea, nasal pruritus, ocular pruritus, tearing, and redness of the eyes Label.
Perennial allergic rhinitis: This drug is indicated for the relief of symptoms associated with perennial allergic rhinitis due to allergens including dust mites, animal dander, and molds in adults and children 6 months of age and older. Symptoms treated effectively include sneezing, rhinorrhea, postnasal discharge, nasal pruritus, ocular pruritus, and tearing Label.
Chronic urticaria: Cetirizine is indicated for the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria in adults and children 6 months of age and older. It markedly reduces the occurrence, severity, and duration of hives and significantly reduces pruritus Label.
General effects and respiratory effects
Cetirizine, the active metabolite of the piperazine H1-receptor antagonist hydroxyzine, minimizes or eliminates the symptoms of chronic idiopathic urticaria, perennial allergic rhinitis, seasonal allergic rhinitis, allergic asthma, physical urticaria, and atopic dermatitis.
The clinical efficacy of cetirizine for allergic respiratory diseases has been well established in numerous trials Label.
Effects on urticaria/anti-inflammatory effects
It has anti-inflammatory properties that may play a role in asthma management 1. There is evidence that cetirizine improves symptoms of urticaria. Marked clinical inhibition of a wheal and flare response occurs in infants, children as well as adults within 20 minutes of one oral dose and lasts for 24 h 1. Concomitant use of cetirizine reduces the duration and dose of topical anti-inflammatory formulas used for the treatment of atopic dermatitis 1.
Cetirizine, a metabolite of hydroxyzine, is an antihistamine drug. Its main effects are achieved through selective inhibition of peripheral H1 receptors. The antihistamine activity of cetirizine has been shown in a variety of animal and human models. In vivo and ex vivo animal models have shown insignificant anticholinergic and antiserotonergic effects. In clinical studies, however, dry mouth was found to be more frequent with cetirizine than with a placebo. In vitro receptor binding studies have demonstrated no detectable affinity of cetirizine for histamine receptors other than the H1 receptors. Studies with radiolabeled cetirizine administration in the rat have demonstrated insignificant penetration into the brain. Ex vivo studies in the mouse have shown that systemically administered cetirizine does not occupy cerebral H1 receptors significantly Label.
Comprehensive structured data on known drug adverse effects with statistical prevalence. MedDRA and ICD10 ids are provided for adverse effect conditions and symptoms.
Structured data covering drug contraindications. Each contraindication describes a scenario in which the drug is not to be used. Includes restrictions on co-administration, contraindicated populations, and more.
Structured data representing warnings from the black box section of drug labels. These warnings cover important and dangerous risks, contraindications, or adverse effects.
Cetirizine was rapidly absorbed with a time to maximum concentration (Tmax) of about 1 hour after oral administration of tablets or syrup formulation in adult volunteers Label. Bioavailability was found to be similar between the tablet and syrup dosage forms. When healthy study volunteers were given several doses of cetirizine (10 mg tablets once daily for 10 days), a mean peak plasma concentration (Cmax) of 311 ng/mL was measured Label.
Effect of food on absorption
Food had no effect on cetirizine exposure (AUC), however, Tmax was delayed by 1.7 hours and Cmax was decreased by 23% in the fed state Label.
Apparent volume of distribution: 0.44 +/- 0.19 L/kg 5.
The mean plasma protein binding of cetirizine is 93% Label.
A mass balance clinical trial comprised of 6 healthy male study volunteers showed that 70% of the administered radioactivity was measured in the urine and 10% in the feces after cetirizine administration. About 50% of the radioactivity was measured in the urine as unchanged cetirizine. Most of the rapid increase in peak plasma radioactivity was related to the parent drug, implying a low level of first pass metabolism. This prevents potential interactions of cetirizine with drugs interacting with hepatic cytochrome enzymes 1.
Cetirizine is metabolized partially by oxidative O-dealkylation to a metabolite with insignificant antihistaminic activity. The enzyme or enzymes responsible for this step in cetirizine metabolism have not yet been identified Label.
Mainly eliminated in the urine Label, 1.
Between 70 – 85% of an orally administered dose can be found in the urine and 10 – 13% in the feces 1.
Plasma elimination half-life is 8.3 hours Label.
Apparent total body clearance: approximately 53 mL/min Label.
Cetirizine is mainly eliminated by the kidneys 1, Label. Dose adjustment is required for patients with moderate to severe renal impairment and in patients on hemodialysis Label.
Oral LD50 (rat): 365 mg/kg; Intraperitoneal LDLO (mouse): 138 mg/kg; Oral TDLO (rat): 50 mg/kg; Oral TDLO (mouse): 0.1 mg/kg MSDS.
Carcinogenesis and mutagenesis: In a 2-year carcinogenicity study in rats, cetirizine was not shown to be carcinogenic at dietary doses up to 20 mg/kg (approximately 15 times the maximum recommended daily oral dose in adults). In a 2-year carcinogenicity study in mice, cetirizine administration lead to an incidence of benign liver tumors in males at a dietary dose of 16 mg/kg (approximately 6 times the maximum recommended daily oral dose in adults). The clinical significance of these findings during long-term use of cetirizine is unknown at this time Label.
Cetirizine was not mutagenic in the Ames test, and not clastogenic in the human lymphocyte assay, the mouse lymphoma assay, and in vivo micronucleus test in rats Label.
Impairment of fertility
In a fertility and reproduction study in mice, cetirizine did not negatively impact fertility at an oral dose of 64 mg/kg (approximately 25 times the maximum recommended daily oral dose in adults) Label.
Pregnancy Category B:
In mice, rats, and rabbits, cetirizine was not teratogenic at oral doses up to 96, 225, and 135 mg/kg, respectively (approximately 40, 180 and 220 times the maximum recommended daily oral dose in adults). There are no adequate and well-controlled studies in pregnant women. Because animal studies are not always predictive of human response, cetirizine should be used in pregnancy only if clearly needed Label.
قرص cetirizine 10
Use in breastfeeding/nursing
Cetirizine has been reported to be excreted in human breast milk. The use of cetirizine in nursing mothers is not recommended Label.
Extended description of the mechanism of action and particular properties of each drug interaction.
A severity rating for each drug interaction, from minor to major.
A rating for the strength of the evidence supporting each drug interaction.
An effect category for each drug interaction. Know how this interaction affects the subject drug.
Manne Reddy, “Polymorphic forms of dihydrochloride salts of cetirizine and processes for preparation thereof.” U.S. Patent US20040186112, issued September 23, 2004.
The date on which a patent was filed with the relevant government.
There is additional data available for commercial users including Adverse Effects, Contraindications, and Blackbox Warnings. Contact us to learn more about these and other features.
Drug created on June 13, 2005 07:24 / Updated on July 08, 2019 12:21
CETIRIZINE HYDROCHLORIDE- cetirizine hydrochloride tablet Kaiser Foundation Hospitals
———-
NDC 0179-8301-01 Original Prescription Strength
Cetirizine Hydrochloride 10 mg Tablets
قرص cetirizine 10
ANTIHISTAMINE / ALLERGY
24 Hour Relief of:
*Compare to Zyrtec ®
100 Tablets
Do not use if imprinted foil inner seal on bottle is broken or missing
Uses: Temporarily relieves these symptoms due to hay fever or other upper respiratory allergies:
Do Not Use if you have ever had an allergic reaction to this product or any of its ingredients or to an antihistamine containing hydroxyzine.
Ask a doctor before use if you have liver or kidney disease. Your doctor should determine if you need a different dose.
Ask a doctor or pharmacist before use if you are taking tranquilizers or sedatives.
Stop use and ask a doctor if an allergic reaction to this product occurs. Seek medical help right away.
Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away. (1-800-222-1222)
Hypromellose, lactose, magnesium stearate, maize starch, polyethylene glycol, povidone, titanium dioxide
Call 1-866-562-4597
قرص cetirizine 10
Original Prescription Strength NDC 0179-8301-01
Cetirizine Hydrochloride 10 mg Tablets
ANTIHISTAMINE I ALLERGY For indoor and outdoor allergies
24 hour relief of:
* Compare to Zyrtec ® 100 Tablets
Cetirizine, sold under the brand name Zyrtec among others, is a second generation antihistamine used to treat hay fever, dermatitis, and urticaria.[5] It is taken by mouth.[6] Effects generally begin within an hour and last for about a day.[6] The degree of benefit is similar to other antihistamines such as diphenhydramine.[6]
Common side effects include sleepiness, dry mouth, headache, and abdominal pain.[6] The degree of sleepiness that occurs is generally less than with first generation antihistamines.[5] Serious side effects may include aggression and angioedema.[5] Use in pregnancy appears safe, but use during breastfeeding is not recommended.[7] The medication works by blocking histamine H1 receptors, mostly outside the brain.[6]
It was patented in 1981 and came into medical use in 1987.[8] It is available as a generic medication.[5] A month’s supply in the United Kingdom costs the NHS about £0.70 as of 2019.[5] In the United States the wholesale cost of this amount is about US$2.50.[9] In 2016 it was the 74th most prescribed medication in the United States, with more than 10 million prescriptions.[10]
Cetirizine’s primary indication is for hay fever and other allergies. Because the symptoms of itching and redness in these conditions are caused by histamine acting on the H1 receptor, blocking those receptors temporarily relieves those symptoms.
قرص cetirizine 10
Cetirizine is also commonly prescribed to treat acute and (in particular cases) chronic urticaria, more efficiently than any other second-generation antihistamine[citation needed].
Cetirizine is available over-the-counter in the US in the form of 5 and 10 mg tablets. A 20 mg strength is available by prescription only.[1]
In the UK up to 30 tablets of 10mg are on the general sales list (of pharmaceuticals) and can be purchased without a prescription and without pharmacist supervision.
Commonly reported side effects of cetirizine include headache (16%), dry mouth (5.7%), drowsiness (5–20%), and fatigue (5.6%), while more serious but rare side effects include cardiac failure, tachycardia, and edema.[11]
Discontinuing cetirizine after prolonged use (typically, use beyond six months) may result in generalized itching.[12][13][14]
Cetirizine acts as a highly selective antagonist of the histamine H1 receptor.[1] 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.[1] 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.[1] 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.[15][16] It shows negligible inhibition of the hERG channel (IC50 > 30 µM)[17] and no cardiotoxicity has been observed with cetirizine at doses of up to 60 mg/day, six times the normal recommended dose[1] and the highest dose of cetirizine that has been studied in healthy subjects.[18]
Cetirizine crosses the blood–brain barrier only slightly, and for this reason, it produces minimal sedation compared to many other antihistamines.[19] A positron emission tomography (PET) study found that brain occupancy of the H1 receptor was 12.6% for 10 mg cetirizine, 25.2% for 20 mg cetirizine, and 67.6% for 30 mg hydroxyzine.[20] (A 10 mg dose of cetirizine equals about a 30 mg dose of hydroxyzine in terms of peripheral antihistamine effect.)[21] PET studies with antihistamines have found that brain H1 receptor occupancy of more than 50% is associated with a high prevalence of somnolence and cognitive decline, whereas brain H1 receptor occupancy of less than 20% is considered to be non-sedative.[22] In accordance, H1 receptor occupancy correlated well with subjective sleepiness for 30 mg hydroxyzine but there was no correlation for 10 or 20 mg cetirizine.[20] As such, brain penetration and brain H1 receptor occupancy by cetirizine are dose-dependent, and in accordance, while cetirizine at doses of 5 to 10 mg have been reported to be non-sedating or mildly sedating, a higher dose of 20 mg has been found to induce significant drowsiness in other studies.[20]
Cetirizine has been shown to inhibit eosinophil chemotaxis and LTB4 release.[23] At a dosage of 20 mg, Boone et al. found that it inhibited the expression of VCAM-1 in patients with atopic dermatitis.[23]
Cetirizine is rapidly and extensively absorbed upon oral administration in tablet or syrup form.[1] The oral bioavailability of cetirizine is at least 70% and of levocetirizine is at least 85%.[3] The Tmax of cetirizine is approximately 1.0 hour regardless of formulation and its onset of action has been reported to be as early as 20 minutes.[2] The pharmacokinetics of cetirizine have been found to increase linearly with dose across a range of 5 to 60 mg.[1] Its Cmax following a single dose has been found to be 257 ng/mL for 10 mg and 580 ng/mL for 20 mg.[2] Food has no effect on the bioavailability of cetirizine but has been found to delay the Tmax by 1.7 hours (i.e., to approximately 2.7 hours) and to decrease the Cmax by 23%.[1][2][24] Similar findings were reported for levocetirizine, which had its Tmax delayed by 1.25 hours and its Cmax decreased by about 36% when administered with a high-fat meal.[24] Steady-state levels of cetirizine occur within 3 days and there is no accumulation of the drug with chronic administration.[2] Following once-daily administration of 10 mg cetirizine for 10 days, the mean Cmax was 311 ng/mL.[25]
The mean plasma protein binding of cetirizine has been found to be 93 to 96% across a range of 25 to 1,000 ng/mL independent of concentration.[2] Plasma protein binding of 88 to 96% has also been reported across multiple studies.[3] The drug is bound to albumin with high affinity, while α1-acid glycoprotein and lipoproteins contribute much less to total plasma protein binding.[3] The unbound or free fraction of levocetirizine has been reported to be 8%.[3] The true volume of distribution of cetirizine is unknown but is estimated to be 0.3 to 0.45 L/kg.[1][3] Cetirizine poorly and slowly crosses the blood–brain barrier, which is due mainly to its chemical properties but also to a minor extent to its activity as a P-glycoprotein substrate.[3]
Cetirizine does not undergo extensive metabolism.[1] It is notably not metabolized by the cytochrome P450 system.[26] Because of this, it does not interact significantly with drugs that inhibit or induce cytochrome P450 enzymes such as theophylline, erythromycin, clarithromycin, cimetidine, or alcohol.[1] While cetirizine does not undergo extensive metabolism or metabolism by the cytochrome P450 enzyme, it does undergo some metabolism by other means, the metabolic pathways of which include oxidation and conjugation.[1][2] Plasma radioactivity attributed to unchanged cetirizine is more than 90% at 2 hours, 80% at 10 hours, and 70% at 24 hours, indicating limited and slow metabolism.[2] The enzymes responsible for transformation of cetirizine have not been identified.[1]
Cetirizine is eliminated approximately 70 to 85% in the urine and 10 to 13% in the feces.[1] About 50 or 60% of cetirizine eliminated in the urine is unchanged.[1][2] It is eliminated in the urine via an active transport mechanism.[2] The elimination half-life of cetirizine ranges from 6.5 to 10 hours in healthy adults, with a mean across studies of approximately 8.3 hours.[1][2] Its duration of action is at least 24 hours.[2] The elimination half-life of cetirizine is increased in the elderly (to 12 hours), in hepatic impairment (to 14 hours), and in renal impairment (to 20 hours).[2]
Cetirizine contains L- and D-stereoisomers. Chemically, levocetirizine is the active L-enantiomer of cetirizine. The drug is a member of the diphenylmethylpiperazine group of antihistamines. Analogues include cyclizine and hydroxyzine.
The 1-[(4-chlorophenylmethyl]-piperazine is alkylated with methyl (2-chloroethoxy)-acetate in the presence of sodium carbonate and xylene solvent to produce the Sn2 substitution product in 28% yield. Saponification of the acetate ester is done by refluxing with potassium hydroxide in absolute ethanol to afford a 56% yield of the potassium salt intermediate. This is then hydrolyzed with aqueous HCl and extracted to give an 81% yield of the carboxylic acid product.
Cetirizine is marketed under the brand names Alatrol, Alerid, Alzene, Cetirin, Cetzine, Cezin, Cetgel, Histazine, Humex, Letizen, Reactine, Razene, Rigix, Triz, Zetop, Zirtec, Zirtek, Zodac, Zyllergy, Zynor, Zyrlek, and Zyrtec among others.
Formerly prescription-only in many countries, cetirizine is now available without prescription in most countries. In some countries it is available over-the-counter only in packages containing seven or ten 10 mg doses.
Like many other antihistamine medications, cetirizine is commonly prescribed in combination with pseudoephedrine, a decongestant. These combinations are often marketed using the same brand name as the cetirizine with a “-D” suffix (Zyrtec-D, Virlix-D, etc.)
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