Dextur

Uses

Cetirizine is used for the treatment of seasonal allergic rhinitis and conjunctivitis, perennial allergic rhinitis, pruritus and urticaria. It is also used in allergen induced asthma.

Dextromethorphan is used for Chronic dry cough or unproductive cough; Acute dry cough which is interfering with normal function or sleep.

Dextur is also used to associated treatment for these conditions: Chronic Idiopathic Urticaria, Flu caused by Influenza, Perennial Allergic Rhinitis (PAR), Pollen Allergy, Respiratory Allergy, Seasonal Allergic RhinitisAllergic cough, Common Cold, Common Cold/Flu, Cough, Cough caused by Common Cold, Coughing caused by Allergies, Coughing caused by Bronchitis, Coughing caused by Flu caused by Influenza, Fever, Flu caused by Influenza, Headache, Irritative cough, Itching of the nose, Itching of the throat, Nasal Congestion, Pseudobulbar affect, Rhinorrhoea, Sneezing, Upper respiratory symptoms, Watery itchy eyes, Airway secretion clearance therapy, Bronchodilation, Oropharyngeal antisepsis

How Dextur works

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 .

Dextromethorphan is an agonist of NMDA and sigma-1 receptors. It is also an antagonist of α3/β4 nicotinic receptors.[A10589] However, the mechanism by which dextromethorphan's receptor agonism and antagonism translates to a clinical effect is not well understood.

Dosage

Dextur dosage

Tablet:

• Adults and children over 6 years: 1 tablet (10 mg) once daily or ½ tablet twice daily.
• Children 2-6 years: ½ tablet once daily.

Syrup:

• Adults and children over 6 years: 2 teaspoonful (10 mg) once daily or 1 teaspoon (5 mg) twice daily.
• Children 2-6 years: 1 teaspoonful once daily or ½ teaspoon twice daily.

Adults and Children over 12 years: 15 to 30 mg three to four times per day. However, 60 mg doses up to four times per day have been used without increased side effects.

Children between 6 and 12 years: 5-15 mg up to four times per day.

Children between 2 and 6 years: 2.5-5 mg up to four times per day.

Side Effects

Cetirizine dihydrochloride is well tolerated. Lower incidence of sedation, headache, dry mouth, and gastrointestinal disturbances may occur. It does not produce anticholinergic effects.

Adverse effects with Dextromethorphan are rare, but nausea and dizziness sometimes occur. The drug produces no analgesia or addiction and little or no CNS depression. Excitation, confusion and respiratory depression may occur after overdosage.

Toxicity

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 .

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 .

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 .

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) .

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 .

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 .

A dextromethorphan overdose may present as nausea, vomiting, stupor, coma, respiratory depression, seizures, tachycardia, hyperexcitability, toxic psychosis, ataxia, nystagmus, dystonia, blurred vision, changes in muscle reflexes, and serotonin syndrome. Overdose should be managed through symptomatic and supportive measures.

Precaution

Caution should be exercised when driving a car or operating a heavy machinery. Concurrent use of cetirizine with alcohol or other CNS depressants should be avoided because additional reduction in alertness and CNS performance may occur.

Do not use Dextromethorphan to control a cough that is associated with smoking, asthma, or emphysema, or a cough that is productive (produces sputum or phlegm).

Interaction

No clinically significant drug interactions have been found with theophylline, azithromycin, pseudoephedrine, ketoconazole or erythromycin and with some other drugs.

The following medicines should be taken carefully while concomitantly use with Dextromethorphan: Amiodarone, Fluoexetine, Quinidine, CNS depressants and Monoamine oxidase (MAO) inhibitors.

Volume of Distribution

Apparent volume of distribution: 0.44 +/- 0.19 L/kg .

The volume of distribution of dextromethorphan is 5-6.7L/kg.

Elimination Route

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 . 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 .

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 .

A 30mg oral dose of dextromethorphan reaches a C_max of 2.9 ng/mL, with a T_max of 2.86 h, and an AUC of 17.8 ng*h/mL.

Half Life

Plasma elimination half-life is 8.3 hours .

Dextromethorphan has a half life of 3-30 hours.

Clearance

Apparent total body clearance: approximately 53 mL/min .

Cetirizine is mainly eliminated by the kidneys , . Dose adjustment is required for patients with moderate to severe renal impairment and in patients on hemodialysis .

Elimination Route

Mainly eliminated in the urine , .

Between 70 – 85% of an orally administered dose can be found in the urine and 10 – 13% in the feces .

Pregnancy & Breastfeeding use

Pregnancy category B. There are no adequate and well controlled studies in pregnant women. Cetirizine should be used during pregnancy only if clearly needed. Cetirizine has been reported to be excreted in human breast milk. As large amount of drugs are excreted in human milk, use of Cetirizine in nursing mother is not recommended.

Pregnancy: Adequate and well-controlled studies in human have not been done. However, Dextromethorphan has not been reported to cause birth defects.

Lactation: It is not known whether dextromethorphan passes into breast milk. However, Dextromethorphan has not been reported to cause problems in nursing babies.

Contraindication

Cetirizine Dihydrochloride is contraindicated in those patients with a known hypersensitivity to it or any of its ingredients or hydroxyzine.

Hypersensitivity to Dextromethorphan or any other component.

Acute Overdose

Symptoms: Confusion, dizziness, fatigue, headache, malaise, restlessness, sedation, somnolence, diarrhoea, mydriasis, pruritus, stupor, tachycardia, tremor, and urinary retention.

Management: Symptomatic and supportive treatment. Gastric lavage may be done shortly following ingestion.

Symptoms: In mild overdose, tachycardia, hypertension, vomiting, mydriasis, diaphoresis, nystagmus, euphoria, loss of motor coordination, and giggling; in moderate intoxication, in addition to those listed above, hallucinations and a plodding ataxic gait; in severely intoxication, agitation or somnolence.

Management: treatment is symptomatic and supportive. Naloxone may be useful in reversing toxicity.

Storage Condition

Store between 20-25°C. Syrup: Store between 2-8°C.

Store at 15-30° C

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