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Zyrtec-D (Cetirizine Hydrochloride / Pseudoephedrine Hydrochloride) - Warnings and Precautions

 
 



WARNINGS

Sympathomimetic amines should be used judiciously and sparingly in patients with hypertension, diabetes mellitus, ischemic heart disease, increased intraocular pressure, hyperthyroidism, renal impairment, or prostatic hypertrophy (see CONTRAINDICATIONS). Sympathomimetic amines may produce central nervous system stimulation with convulsions or cardiovascular collapse with accompanying hypotension. The elderly are more likely to have adverse reactions to sympathomimetic amines.

PRECAUTIONS

Due to its pseudoephedrine component, ZYRTEC-D 12 HOUR Extended Release Tablets should be used with caution in patients with hypertension, diabetes mellitus, ischemic heart disease, increased intraocular pressure, hyperthyroidism, renal impairment, or prostatic hypertrophy (see WARNINGS and CONTRAINDICATIONS). Patients with decreased renal function should be given a lower initial dose (one tablet per day) because they have reduced elimination of cetirizine and pseudoephedrine (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).

Activities Requiring Mental Alertness

In clinical trials, the occurrence of somnolence has been reported in some patients taking cetirizine or ZYRTEC -D 12 HOUR Extended Release Tablets; due caution should therefore be exercised when driving a car or operating potentially dangerous machinery after taking ZYRTEC-D 12 HOUR Extended Release Tablets. Concurrent use of ZYRTEC-D 12 HOUR Extended Release Tablets with alcohol or other CNS depressants should be avoided because additional reductions in alertness and additional impairment of CNS performance may occur.

Drug Interactions

Cetirizine hydrochloride and pseudoephedrine hydrochloride do not influence the pharmacokinetics of each other when administered concomitantly.

No clinically significant drug interactions have been found with cetirizine and theophylline at a low dose, azithromycin, ketoconazole, or erythromycin. There was a small decrease in the clearance of cetirizine caused by a 400 mg dose of theophylline; it is possible that larger theophylline doses could have a greater effect.

Due to the pseudoephedrine component, ZYRTEC-D 12 HOUR Extended Release Tablets are contraindicated in patients taking monoamine oxidase (MAO) inhibitors and for 14 days after stopping use of an MAO inhibitor. Concomitant use with antihypertensive drugs that interfere with sympathetic activity (e.g., methyldopa, mecamylamine, and reserpine) may reduce their antihypertensive effects. Increased ectopic pacemaker activity can occur when pseudoephedrine is used concomitantly with digitalis. Care should be taken in the administration of ZYRTEC-D 12 HOUR Extended Release Tablets concomitantly with other sympathomimetic amines because combined effects on the cardiovascular system may be harmful to the patient (see WARNINGS).

Carcinogenesis, Mutagenesis and Impairment of Fertility

There are no carcinogenicity trials of pseudoephedrine and cetirizine in combination.

Cetirizine

In a 2-year study in rats, cetirizine was not carcinogenic at dietary doses up to 20 mg/kg (approximately 15 times the maximum recommended daily dose in adults on a mg/m2 basis). In a 2-year study in mice, cetirizine caused an increased incidence of benign liver tumors in males at a dietary dose of 16 mg/kg (approximately 6 times the maximum recommended daily dose in adults on a mg/m2 basis). No increase in the incidence of liver tumors was observed in mice at a dietary dose of 4 mg/kg (approximately 2 times the maximum recommended daily dose in adults on a mg/m2 basis). The clinical significance of these findings during long-term use of ZYRTEC-D 12 HOUR Extended Release Tablets is not known.

Pseudoephedrine

Two-year studies in rats and mice conducted under the auspices of the National Toxicology Program (NTP) demonstrated no evidence of carcinogenic potential with ephedrine sulfate, a structurally related drug with pharmacological properties similar to pseudoephedrine, at dietary doses up to 10 and 27 mg/kg, respectively (approximately 1/3 and 1/2, respectively, the maximum recommended daily dose of pseudoephedrine in adults on a mg/m2 basis).

Cetirizine was not mutagenic in the Ames test or mouse lymphoma test and not clastogenic in the human lymphocyte assay or the in vivo rodent micronucleus test. Likewise, the combination of cetirizine and pseudoephedrine in a 1:24 ratio was not mutagenic or clastogenic in these tests. However, the Ames and mouse lymphoma assays did not strictly adhere to test standards.

In a reproductive toxicity study in rats, combination oral doses of cetirizine and pseudoephedrine up to 6/154 mg/kg (approximately 5 times the maximum recommended daily dose in adults on a mg/m2 basis) had no effect on fertility.

Pregnancy Category C

In rats, the combination of cetirizine and pseudoephedrine caused developmental toxicity when administered orally at 6/154 mg/kg (approximately 5 times the maximum recommended daily dose in adults on a mg/m2 basis). When rats were dosed throughout pregnancy with oral doses of cetirizine/pseudoephedrine, 6/154 mg/kg increased the number of fetal skeletal malformations (rib distortions) and variants (unossified sternebrae). When dosing was continued through lactation, 6/154 mg/kg also decreased the viability and weight gain of offspring. These effects were not observed at 1.6/38 mg/kg (approximately equivalent to the maximum recommended daily dose in adults on a mg/m2 basis). No embryofetal toxicity was observed when rabbits were dosed throughout organogenesis with oral doses of cetirizine/pseudoephedrine of up to 6/154 mg/kg (approximately 10 times the maximum recommended daily dose in adults on a mg/m2 basis). Because there are no adequate and well-controlled trials in pregnant women, ZYRTEC-D 12 HOUR Extended Release Tablets should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

In rats the combination of cetirizine/pseudoephedrine decreased the viability and weight gain of offspring when administered orally to dams throughout pregnancy and lactation at 6/154 mg/kg (approximately 5 times the maximum recommended daily dose in adults on a mg/m2 basis). This effect was not observed at 1.6/38 mg/kg (approximately equivalent to the maximum recommended daily dose in adults on a mg/m2 basis). For cetirizine administered alone, studies in dogs indicate that approximately 3% of the dose is excreted in milk, and cetirizine has been reported to be excreted in human breast milk. For pseudoephedrine administered alone, 0.4–0.7% of the dose has been reported to be excreted in human breast milk.

Because cetirizine and pseudoephedrine are excreted in milk, use of ZYRTEC-D 12 HOUR Extended Release Tablets in nursing mothers is not recommended.

Geriatric Use

Clinical trials of ZYRTEC-D 12 HOUR Extended Release Tablets did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, although the elderly are more likely to have adverse reactions to sympathomimetic amines. In general, dosing in an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

The cetirizine and pseudoephedrine components of ZYRTEC-D 12 HOUR Extended Release Tablets are known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function (see CLINICAL PHARMACOLOGY).

Cetirizine

Of the total number of subjects in clinical trials of cetirizine alone, 186 were 65 years and over, while 39 were 75 years and over. No overall differences in safety were observed between these subjects and younger subjects, and other reported experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. With regard to efficacy, clinical trials of cetirizine for each approved indication did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently than younger patients.

Pediatric Use

ZYRTEC-D 12 HOUR Extended Release Tablets contain 120 mg of pseudoephedrine hydrochloride in an extended release formulation. This dose of pseudoephedrine exceeds the recommended dose for pediatric patients under 12 years of age. Therefore, clinical trials of ZYRTEC-D 12 HOUR Extended Release Tablets have not been conducted in patients under 12 years of age.

Page last updated: 2006-02-06

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