• Zyrex indications
• Uses of Zyrex in details
• Zyrex description
• Zyrex dosage
• Zyrex interactions
• Zyrex side effects
• Zyrex contraindications

What is Zyrex?

Zyrex is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Zyrex is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose.

Zyrex is also used to treat itching and swelling caused by chronic urticaria (hives).

Zyrex may also be used for purposes not listed in this medication guide.

Zyrex indications

Perennial Allergic Rhinitis: Zyrex syrup is indicated for the relief of symptoms associated with perennial allergic rhinitis due to allergens such as dust mites, animal dander and molds in children 6 to 23 months of age. Symptoms treated effectively include sneezing, rhinorrhea, postnasal discharge, nasal pruritus, ocular pruritus, and tearing.

Chronic Urticaria: Zyrex syrup is indicated for the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria in children 6 months to 5 years of age. It significantly reduces the occurrence, severity, and duration of hives and significantly reduces pruritus.

How should I use Zyrex?

Use Zyrex as directed by your doctor. Check the label on the medicine for exact dosing instructions.

• Do not remove the blister unit from the carton until you are ready to take Zyrex. Make sure that your hands are dry when you open the blister unit. Do not push the tablet through the foil. Peel back the foil on the blister unit and place the tablet on your tongue. The tablet dissolves quickly and can be swallowed with saliva. Zyrex may be taken with or without water. Take the tablet immediately after opening the blister unit. Do not store the removed tablet for future use.
• If you miss a dose of Zyrex and you are taking it regularly, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use Zyrex.

Uses of Zyrex in details

Use: Labeled Indications

Oral:

Allergic rhinitis: Relief of symptoms associated with allergic rhinitis.

Urticaria, chronic spontaneous: Treatment of uncomplicated skin manifestations of chronic spontaneous urticaria.

Injection:

Urticaria, acute: Treatment of acute urticaria.

Off Label Uses

Anaphylaxis (adjunct to epinephrine for relief of cutaneous symptoms)

Based on joint guidelines from the American Academy of Allergy, Asthma & Immunology, American College of Allergy, Asthma & Immunology, and Joint Council of Allergy, Asthma and Immunology on the diagnosis and management of anaphylaxis and guidelines from the World Allergy Organization on anaphylaxis, Zyrex may be used as adjunctive treatment, although should not be used as monotherapy or as first-line therapy of anaphylaxis.

Angioedema, acute allergic or recurrent idiopathic

Clinical experience suggests the utility of second-generation H receptor antagonists (eg, Zyrex) for the treatment of acute allergic or recurrent idiopathic angioedema.

Zyrex description

Zyrex HCl is a piperazine derivative and a metabolite of hydroxyzine. It competes reversibly with histamine to block the histamine (H₁) receptor sites. Zyrex HCl is considered a long-acting nonsedating antihistamine and has some mast-cell stabilizing activity.

Zyrex dosage

Zyrex Dosage

Applies to the following strength(s): 10 mg; 5 mg; 1 mg/mL

The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.

Usual Adult Dose for:

• Allergic Rhinitis
• Urticaria

Usual Pediatric Dose for:

• Allergic Rhinitis
• Urticaria

Additional dosage information:

• Renal Dose Adjustments
• Liver Dose Adjustments
• Precautions
• Dialysis

Usual Adult Dose for Allergic Rhinitis

5 to 10 mg orally or chewed once a day

Usual Adult Dose for Urticaria

5 to 10 mg orally or chewed once a day

Usual Pediatric Dose for Allergic Rhinitis

6 months to 2 years: 2.5 mg orally once a day, 12 months and older may be increased to 2.5 mg orally twice a day.

2 to 5 years: 2.5 mg orally once a day, may be increased to 5 mg/day in 1 to 2 divided doses.

6 years or older: 5 to 10 mg orally or chewed once a day.

Usual Pediatric Dose for Urticaria

6 months to 2 years: 2.5 mg orally once a day, 12 months and older may be increased to 2.5 mg orally twice a day.

2 to 5 years: 2.5 mg orally once a day, may be increased to 5 mg/day in 1 to 2 divided doses.

6 years or older: 5 to 10 mg orally or chewed once a day.

Renal Dose Adjustments

CrCl less than 30 mL/min: 5 mg orally or chewed once a day.

Use of Zyrex is not recommended in children under 6 years of age with renal impairment due to the difficulty in reliably administering doses less than 2.5 mg (1/2 teaspoonful) and the lack of pharmacokinetic and safety information of Zyrex in such patients.

Liver Dose Adjustments

5 mg orally or chewed once a day

Use of Zyrex is not recommended in children under 6 years of age with hepatic impairment due to the difficulty in reliably administering doses less than 2.5 mg (1/2 teaspoonful) and the lack of pharmacokinetic and safety information of Zyrex in such patients.

Precautions

In clinical trials, the occurrence of somnolence has been reported. Due caution should therefore be exercised when driving a car or operating potential dangerous machinery. Concurrent use of alcohol or other CNS depressants should be avoided because additional reductions in alertness and additional impairment of CNS performance may occur.

Dialysis

Zyrex is not significantly removed by hemodialysis, thus supplementary dosing is not required following hemodialysis. The recommended dosage for patients on hemodialysis is 5 mg orally or chewed once a day.

More about Zyrex

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Consumer resources

• Zyrex
• Zyrex chewable tablets
• Zyrex
• Zyrex solution

• Other brands: Zyrtec, Children's Zyrtec, Zyrtec Hives, Zyrex, More (1) »

Professional resources

• Zyrex (AHFS Monograph)
• More (8) »

Related treatment guides

• Allergic Rhinitis
• Urticaria

Zyrex interactions

See also:
What other drugs will affect Zyrex?

Tablet: Concurrent use with alcohol may potentiate the CNS depressant effects of Zyrex; maprotiline or tricyclic antidepressants may potentiate the anticholinergic effects of either these medications or Zyrex.

Monoamine oxidase (MAO) inhibitors are not recommended because the use may prolong and intensify the anticholinergic and CNS depressant effects of Zyrex.

Concurrent use with ototoxic medications may mask the symptoms of ototoxicity eg, tinnitus, dizziness or vertigo; photosensitizing medications may cause additive photosensitizing effects.

Syrup: No interaction is observed for Zyrex with pseudoephedrine, cimetidine, ketoconazole, erythromycin and azithromycin. Small decrease in Zyrex clearance is observed when theophylline (400 mg once daily) is taken with Zyrex. However, disposition of theophylline was not altered by concomitant Zyrex administration. Concomitant administration of Zyrex and macrolides or ketoconazole has never resulted clinically relevant EGG changes. Extent of exposure to Zyrex was increased by 40% when ritonavir is taken with Zyrex. Disposition of ritonavir was slightly altered further to concomitant Zyrex administration.

Zyrex side effects

See also:
What are the possible side effects of Zyrex?

Pediatric studies were conducted with Zyrex. More than 1300 pediatric patients aged 6 to 11 years with more than 900 treated with Zyrex at doses of 1.25 to 10 mg per day were included in controlled and uncontrolled clinical trials conducted in the United States. The duration of treatment ranged from 2 to 12 weeks. Placebo-controlled trials up to 4 weeks duration included 168 pediatric patients aged 2 to 5 years who received Zyrex, the majority of whom received single daily doses of 5 mg. A placebo-controlled trial 18 months in duration included 399 patients aged 12 to 24 months treated with Zyrex (0.25 mg/kg bid), and another placebo-controlled trial of 7 days duration included 42 patients aged 6 to 11 months who were treated with Zyrex (0.25 mg/kg bid).

The majority of adverse reactions reported in pediatric patients aged 2 to 11 years with Zyrex were mild or moderate. In placebo-controlled trials, the incidence of discontinuations due to adverse reactions in pediatric patients receiving up to 10 mg of Zyrex was uncommon (0.4% on Zyrex vs. 1.0% on placebo).

Table 1 lists adverse experiences which were reported for Zyrex 5 and 10 mg in pediatric patients aged 6 to 11 years in placebo-controlled clinical trials in the United States and were more common with Zyrex than placebo. Of these, abdominal pain was considered treatment-related and somnolence appeared to be dose-related, 1.3% in placebo, 1.9% at 5 mg and 4.2% at 10 mg. The adverse experiences reported in pediatric patients aged 2 to 5 years in placebo-controlled trials were qualitatively similar in nature and generally similar in frequency to those reported in trials with children aged 6 to 11 years.

In the placebo-controlled trials of pediatric patients 6 to 24 months of age, the incidences of adverse experiences, were similar in the Zyrex and placebo treatment groups in each study. Somnolence occurred with essentially the same frequency in patients who received Zyrex and patients who received placebo. In a study of 1 week duration in children 6 to 11 months of age, patients who received Zyrex exhibited greater irritability/fussiness than patients on placebo. In a study of 18 months duration in patients 12 months and older, insomnia occurred more frequently in patients who received Zyrex compared to patients who received placebo (9.0% v. 5.3%). In those patients who received 5 mg or more per day of Zyrex as compared to patients who received placebo, fatigue (3.6% v. 1.3%) and malaise (3.6% v. 1.8%) occurred more frequently.

Table 1.

Adverse Experiences Reported in Pediatric Patients Aged 6 to 11 Years in Placebo-Controlled United States Zyrex Trials (5 or 10 mg Dose) Which Occurred at a Frequency of ≥2% in Either the 5-mg or the 10-mg Zyrex Group, and More Frequently Than in the Placebo Group

The following events were observed infrequently (less than 2%), in either 3982 adults and children 12 years and older or in 659 pediatric patients aged 6 to 11 years who received Zyrex in U.S. trials, including an open adult study of six months duration. A causal relationship of these infrequent events with Zyrex administration has not been established.

Autonomic Nervous System: anorexia, flushing, increased salivation, urinary retention.

Cardiovascular: cardiac failure, hypertension, palpitation, tachycardia.

Central and Peripheral Nervous Systems: abnormal coordination, ataxia, confusion, dysphonia, hyperesthesia, hyperkinesia, hypertonia, hypoesthesia, leg cramps, migraine,

myelitis, paralysis, paresthesia, ptosis, syncope, tremor, twitching, vertigo, visual field defect.

Gastrointestinal: abnormal hepatic function, aggravated tooth caries, constipation, dyspepsia, eructation, flatulence, gastritis, hemorrhoids, increased appetite, melena, rectal hemorrhage, stomatitis including ulcerative stomatitis, tongue discoloration, tongue edema.

Genitourinary: cystitis, dysuria, hematuria, micturition frequency, polyuria, urinary incontinence, urinary tract infection.

Hearing and Vestibular: deafness, earache, ototoxicity, tinnitus.

Metabolic/Nutritional: dehydration, diabetes mellitus, thirst.

Musculoskeletal: arthralgia, arthritis, arthrosis, muscle weakness, myalgia.

Psychiatric: abnormal thinking, agitation, amnesia, anxiety, decreased libido, depersonalization, depression, emotional lability, euphoria, impaired concentration, insomnia, nervousness, paroniria, sleep disorder.

Respiratory System: bronchitis, dyspnea, hyperventilation, increased sputum, pneumonia, respiratory disorder, rhinitis, sinusitis, upper respiratory tract infection.

Reproductive: dysmenorrhea, female breast pain, intermenstrual bleeding, leukorrhea, menorrhagia, vaginitis.

Reticuloendothelial: lymphadenopathy.

Skin: acne, alopecia, angioedema, bullous eruption, dermatitis, dry skin, eczema, erythematous rash, furunculosis, hyperkeratosis, hypertrichosis, increased sweating, maculopapular rash, photosensitivity reaction, photosensitivity toxic reaction, pruritus, purpura, rash, seborrhea, skin disorder, skin nodule, urticaria.

Special Senses: parosmia, taste loss, taste perversion.

Vision: blindness, conjunctivitis, eye pain, glaucoma, loss of accommodation, ocular hemorrhage, xerophthalmia.

Body as a Whole: accidental injury, asthenia, back pain, chest pain, enlarged abdomen, face edema, fever, generalized edema, hot flashes, increased weight, leg edema, malaise, nasal polyp, pain, pallor, periorbital edema, peripheral edema, rigors.

Occasional instances of transient, reversible hepatic transaminase elevations have occurred during Zyrex therapy. Hepatitis with significant transaminase elevation and elevated bilirubin in association with the use of Zyrex has been reported.

Post-Marketing Experience

In the post-marketing experience period, the following additional rare, but potentially severe adverse events have been reported: aggressive reaction, anaphylaxis, cholestasis, convulsions, glomerulonephritis, hallucinations, hemolytic anemia, hepatitis, orofacial dyskinesia, severe hypotension, stillbirth, suicidal ideation, suicide and thrombocytopenia.

Zyrex contraindications

See also:
What is the most important information I should know about Zyrex?

Tablet: Zyrex should not be used except under special circumstances for patients with hepatic and renal function impairment.

The risk-benefit should be considered when medical problems eg, bladder neck obstruction, prostatic hypertrophy, urinary retention and glaucoma exists.

Syrup: Hypersensitivity to Zyrex dihydrochloride, hydroxyzine, any piperazine derivatives or to any of the excipients of Zyrex. Patients with severe renal impairment CrCl <10 mL/min. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take Zyrex.

Active ingredient matches for Zyrex:

Cetirizine in Thailand.

Ambroxol/Guaifenesin/Terbutaline

Cefuroxime Na in Philippines.

Cetirizine Hcl

Cetirizine hydrochloride in Thailand.

Ambroxol hydrochloride/guaiphenesin/menthol/terbutaline sulphate in India.

References

1. DailyMed. "TERBUTALINE SULFATE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
2. DailyMed. "GUAIFENESIN; HYDROCODONE BITARTRATE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
3. DailyMed. "CETIRIZINE HYDROCHLORIDE; PSEUDOEPHEDRINE HYDROCHLORIDE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).

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Information checked by Dr. Sachin Kumar, MD Pharmacology