In vitro data indicate that levocetirizine is unlikely to produce pharmacokinetic interactions through inhibition or induction of liver drug-metabolizing enzymes. No in vivo drug-drug interaction studies have been performed with levocetirizine. Drug interaction studies have been performed with racemic cetirizine.
7.1 Antipyrine, Azithromycin, Cimetidine, Erythromycin, Ketoconazole, Theophylline, and Pseudoephedrine
Pharmacokinetic interaction studies performed with racemic cetirizine demonstrated that cetirizine did not interact with antipyrine, pseudoephedrine, erythromycin, azithromycin, ketoconazole, and cimetidine. There was a small decrease (~16%) in the clearance of cetirizine caused by a 400 mg dose of theophylline. It is possible that higher theophylline doses could have a greater effect.
Ritonavir increased the plasma AUC of cetirizine by about 42% accompanied by an increase in half-life (53%) and a decrease in clearance (29%) of cetirizine. The disposition of ritonavir was not altered by concomitant cetirizine administration.
Available data from published literature and postmarketing experience with levocetirizine use in pregnant women are insufficient to identify any drug-associated risks of miscarriage, birth defects, or adverse maternal or fetal outcomes. In animal reproduction studies, there was no evidence of fetal harm with administration of levocetirizine by the oral route to pregnant rats and rabbits, during the period of organogenesis, at doses up to 390 times and 470 times, respectively, the maximum recommended human dose (MRHD) in adults. In rats treated during late gestation and the lactation period, cetirizine had no effects on pup development at oral doses up to approximately 60 times the MRHD in adults. In mice treated during late gestation and the lactation period, cetirizine administered by the oral route to the dams had no effects on pup development at a dose that was approximately 25 times the MRHD in adults; however, lower pup weight gain during lactation was observed at a dose that was 95 times the MRHD in adults [see Data].
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risks of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
In embryo-fetal development studies, pregnant rats received daily doses of levocetirizine up to 200 mg/kg/day from gestation days 6 to 15 and pregnant rabbits received daily doses of levocetirizine up to 120 mg/kg/day from gestation days 6 to 18. Levocetirizine produced no evidence of fetal harm in rats and rabbits at doses up to 390 and 470 times the MRHD, respectively (on a mg/m2 basis with maternal oral doses of 200 and 120 mg/kg/day in rats and rabbits, respectively). No prenatal and postnatal development (PPND) studies in animals have been conducted with levocetirizine. In a PPND study conducted in mice, cetirizine was administered at oral doses up to 96 mg/kg/day from gestation day 15 through lactation day 21. Cetirizine lowered pup body weight gain during lactation at an oral dose in dams that was approximately 95 times the MRHD (on a mg/m2 basis with a maternal oral dose of 96 mg/kg/day); however, there were no effects on pup weight gain at an oral dose in dams that was approximately 25 times the MRHD (on a mg/m2 basis with a maternal oral dose of 24 mg/kg/day). In a PPND study conducted in rats, cetirizine was administered at oral doses up to 180 mg/kg/day from gestation day 17 to lactation day 22. Cetirizine did not have any adverse effects on rat dams or offspring development at doses up to approximately 60 times the MRHD (on a mg/m2 basis with a maternal oral dose of 30 mg/kg/day). Cetirizine caused excessive maternal toxicity at an oral dose in dams that was approximately 350 times the MRHD (on a mg/m2 basis with a maternal oral dose of 180 mg/kg/day).
There are no data on the presence of levocetirizine in human milk, the effects on the breastfed infant, or the effects on milk production. However, cetirizine has been reported to be present in human breast milk. In mice and beagle dogs, studies indicated that cetirizine was excreted in milk [see Data]. When a drug is present in animal milk, it is likely the drug will be present in human milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for levocetirizine and any potential adverse effects on the breastfed child from levocetirizine or from the underlying maternal condition.
Cetirizine was detected in the milk of mice. No adverse developmental effects on pups were seen when cetirizine was administered orally to dams during lactation at a dose that was approximately 25 times the MRHD in adults [see Use in Specific Populations (8.1) ]. Studies in beagle dogs indicated that approximately 3% of the dose of cetirizine was excreted in milk. The concentration of drug in animal milk does not necessarily predict the concentration of drug in human milk.
The recommended dose of levocetirizine dihydrochloride for the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria in patients 6 months to 17 years of age is based on extrapolation of efficacy from adults 18 years of age and older [see Clinical Studies (14)].
The recommended dose of levocetirizine dihydrochloride in patients 6 years to 11 years of age with chronic idiopathic urticaria is based on cross-study comparisons of the systemic exposure of levocetirizine dihydrochloride in adults and pediatric patients and on the safety profile of levocetirizine dihydrochloride in both adult and pediatric patients at doses equal to or higher than the recommended dose for patients 6 months to 11 years of age.
The safety of levocetirizine dihydrochloride 5 mg once daily was evaluated in 243 pediatric patients 6 to 12 years of age in two placebo-controlled clinical trials lasting 4 and 6 weeks. The safety of levocetirizine dihydrochloride 1.25 mg twice daily was evaluated in one 2-week clinical trial in 114 pediatric patients 1 to 5 years of age and the safety of levocetirizine dihydrochloride 1.25 mg once daily was evaluated in one 2-week clinical trial in 45 pediatric patients 6 to 11 months of age [see Adverse Reactions (6.1)].
The effectiveness of levocetirizine dihydrochloride 2.5 mg once daily (6 to 11 years of age) for the treatment of the symptoms of chronic idiopathic urticaria is supported by the extrapolation of demonstrated efficacy of levocetirizine dihydrochloride 5 mg once daily in patients 12 years of age and older based on the pharmacokinetic comparison between adults and children.
Cross-study comparisons indicate that administration of a 5 mg dose of levocetirizine dihydrochloride to 6 to 12 year old pediatric patients resulted in about 2-fold the systemic exposure (AUC) observed when 5 mg of levocetirizine dihydrochloride was administered to healthy adults. Therefore, in children 6 to 11 years of age the recommended dose of 2.5 mg once daily should not be exceeded. In a population pharmacokinetics study the administration of 1.25 mg once daily in children 6 months to 5 years of age resulted in systemic exposure comparable to 5 mg once daily in adults [see Dosage and Administration (2.2), Clinical Studies (14), and Clinical Pharmacology (12.3)].
Clinical studies of levocetirizine dihydrochloride for each approved indication did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently than younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.
Levocetirizine dihydrochloride is known to be substantially excreted by the kidneys and the risk of adverse 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 Dosage and Administration (2) and Clinical Pharmacology (12.3) ].
As levocetirizine is mainly excreted unchanged by the kidneys, it is unlikely that the clearance of levocetirizine is significantly decreased in patients with solely hepatic impairment [see Clinical Pharmacology (12.3) ].
Overdosage has been reported with levocetirizine dihydrochloride.
Symptoms of overdose may include drowsiness in adults. In children agitation and restlessness may initially occur, followed by drowsiness. There is no known specific antidote to levocetirizine dihydrochloride. Should overdose occur, symptomatic or supportive treatment is recommended. Levocetirizine dihydrochloride is not effectively removed by dialysis, and dialysis will be ineffective unless a dialyzable agent has been concomitantly ingested.
The acute maximal non-lethal oral dose of levocetirizine was 240 mg/kg in mice (approximately 190 times the maximum recommended daily oral dose in adults, approximately 230 times the maximum recommended daily oral dose in children 6 to 11 years of age, and approximately 180 times the maximum recommended daily oral dose in children 6 months to 5 years of age on a mg/m2 basis). In rats the maximal non-lethal oral dose was 240 mg/kg (approximately 390 times the maximum recommended daily oral dose in adults, approximately 460 times the maximum recommended daily oral dose in children 6 to 11 years of age, and approximately 370 times the maximum recommended daily oral dose in children 6 months to 5 years of age on a mg/m2 basis).
Levocetirizine dihydrochloride, USP the active component of levocetirizine dihydrochloride tablets USP is an orally active H1-receptor antagonist. The chemical name is (R)-[2-[4-[(4-chlorophenyl) phenylmethyl]-1-piperazinyl] ethoxy] acetic acid dihydrochloride. Levocetirizine dihydrochloride USP is the R enantiomer of cetirizine hydrochloride, a racemic compound with antihistaminic properties. The molecularl formula of levocetirizine dihydrochloride USP is C21 H25 ClN2 O3 •2HCl. The molecular weight is 461.82 and the chemical structure is shown below:
Levocetirizine dihydrochloride USP is a white, crystalline powder and is water soluble.
Levocetirizine dihydrochloride 5 mg tablets are formulated as immediate release, white to off-white, biconvex, film-coated, oval-shaped scored tablets for oral administration. The tablets are debossed on one side with ‘M 17’. Inactive ingredients are: microcrystalline cellulose, croscarmellose sodium, lactose monohydrate, colloidal anhydrous silica, and magnesium stearate. The film coating contains hypromellose, titanium dioxide, and macrogol 400.
Levocetirizine, the active enantiomer of cetirizine, is an antihistamine; its principal effects are mediated via selective inhibition of H1 receptors. The antihistaminic activity of levocetirizine has been documented in a variety of animal and human models. In vitro binding studies revealed that levocetirizine has an affinity for the human H1 -receptor 2-fold higher than that of cetirizine (Ki = 3 nmol/L vs. 6 nmol/L, respectively). The clinical relevance of this finding is unknown.
Studies in adult healthy subjects showed that levocetirizine at doses of 2.5 mg and 5 mg inhibited the skin wheal and flare caused by the intradermal injection of histamine. In contrast, dextrocetirizine exhibited no clear change in the inhibition of the wheal and flare reaction. Levocetirizine at a dose of 5 mg inhibited the wheal and flare caused by intradermal injection of histamine in 14 pediatric subjects (aged 6 to 11 years) and the activity persisted for at least 24 hours. The clinical relevance of histamine wheal skin testing is unknown.
A QT/QTc study using a single dose of 30 mg of levocetirizine did not demonstrate an effect on the QTc interval. While a single dose of levocetirizine had no effect, the effects of levocetirizine may not be at steady state following single dose. The effect of levocetirizine on the QTc interval following multiple dose administration is unknown. Levocetirizine is not expected to have QT/QTc effects because of the results of QTc studies with cetirizine and the long post-marketing history of cetirizine without reports of QT prolongation.
Levocetirizine exhibited linear pharmacokinetics over the therapeutic dose range in adult healthy subjects.
Levocetirizine is rapidly and extensively absorbed following oral administration. In adults, peak plasma concentrations are achieved 0.9 hour after administration of the oral tablet. The accumulation ratio following daily oral administration is 1.12 with steady state achieved after 2 days. Peak concentrations are typically 270 ng/mL and 308 ng/mL following a single and a repeated 5 mg once daily dose, respectively. Food had no effect on the extent of exposure (AUC) of the levocetirizine tablet, but Tmax was delayed by about 1.25 hours and Cmax was decreased by about 36% after administration with a high fat meal; therefore, levocetirizine can be administered with or without food.
The mean plasma protein binding of levocetirizine in vitro ranged from 91 to 92%, independent of concentration in the range of 90-5000 ng/mL, which includes the therapeutic plasma levels observed. Following oral dosing, the average apparent volume of distribution is approximately 0.4 L/kg, representative of distribution in total body water.
The extent of metabolism of levocetirizine in humans is less than 14% of the dose and therefore differences resulting from genetic polymorphism or concomitant intake of hepatic drug metabolizing enzyme inhibitors are expected to be negligible. Metabolic pathways include aromatic oxidation, N- and O-dealkylation, and taurine conjugation. Dealkylation pathways are primarily mediated by CYP 3A4 while aromatic oxidation involves multiple and/or unidentified CYP isoforms.
The plasma half-life in adult healthy subjects was about 8 to 9 hours after administration of oral tablets and oral solution, and the mean oral total body clearance for levocetirizine was approximately 0.63 mL/kg/min. The major route of excretion of levocetirizine and its metabolites is via urine, accounting for a mean of 85.4% of the dose. Excretion via feces accounts for only 12.9% of the dose. Levocetirizine is excreted both by glomerular filtration and active tubular secretion. Renal clearance of levocetirizine correlates with that of creatinine clearance. In patients with renal impairment the clearance of levocetirizine is reduced [see Dosage and Administration (2.2) ].
Drug Interaction Studies
In vitro data on metabolite interaction indicate that levocetirizine is unlikely to produce, or be subject to metabolic interactions. Levocetirizine at concentrations well above Cmax level achieved within the therapeutic dose ranges is not an inhibitor of CYP isoenzymes 1A2, 2C9, 2C19, 2A1, 2D6, 2E1, and 3A4, and is not an inducer of UGT1A or CYP isoenzymes 1A2, 2C9 and 3A4.
No formal in vivo drug interaction studies have been performed with levocetirizine. Studies have been performed with the racemic cetirizine [see Drug Interactions (7) ].
Data from a pediatric pharmacokinetic study with oral administration of a single dose of 5 mg levocetirizine in 14 children age 6 to 11 years with body weight ranging between 20 and 40 kg show that Cmax and AUC values are about 2-fold greater than that reported in healthy adult subjects in a cross-study comparison. The mean Cmax was 450 ng/mL, occurring at a mean time of 1.2 hours, weight-normalized, total body clearance was 30% greater, and the elimination half-life 24% shorter in this pediatric population than in adults.
Dedicated pharmacokinetic studies have not been conducted in pediatric patients younger than 6 years of age. A retrospective population pharmacokinetic analysis was conducted in 323 subjects (181 children 1 to 5 years of age, 18 children 6 to 11 years of age, and 124 adults 18 to 55 years of age) who received single or multiple doses of levocetirizine ranging from 1.25 mg to 30 mg. Data generated from this analysis indicated that administration of 1.25 mg once daily to children 6 months to 5 years of age results in plasma concentrations similar to those of adults receiving 5 mg once daily.
Limited pharmacokinetic data are available in elderly subjects. Following once daily repeat oral administration of 30 mg levocetirizine for 6 days in 9 elderly subjects (65–74 years of age), the total body clearance was approximately 33% lower compared to that in younger adults. The disposition of racemic cetirizine has been shown to be dependent on renal function rather than on age. This finding would also be applicable for levocetirizine, as levocetirizine and cetirizine are both predominantly excreted in urine. Therefore, the levocetirizine dihydrochloride dose should be adjusted in accordance with renal function in elderly patients [seeDosage and Administration (2) ].
Pharmacokinetic results for 77 patients (40 men, 37 women) were evaluated for potential effect of gender. The half-life was slightly shorter in women (7.08 ± 1.72 hr) than in men (8.62 ± 1.84 hr); however, the body weight-adjusted oral clearance in women (0.67 ± 0.16 mL/min/kg) appears to be comparable to that in men (0.59 ± 0.12 mL/min/kg). The same daily doses and dosing intervals are applicable for men and women with normal renal function.
The effect of race on levocetirizine has not been studied. As levocetirizine is primarily renally excreted, and there are no important racial differences in creatinine clearance, pharmacokinetic characteristics of levocetirizine are not expected to be different across races. No race-related differences in the kinetics of racemic cetirizine have been observed.
Levocetirizine exposure (AUC) exhibited 1.8-, 3.2-, 4.3-, and 5.7-fold increase in mild, moderate, severe, renal impaired, and end-stage renal disease patients, respectively, compared to healthy subjects. The corresponding increases of half-life estimates were 1.4-, 2.0-, 2.9-, and 4-fold, respectively.
The total body clearance of levocetirizine after oral dosing was correlated to the creatinine clearance and was progressively reduced based on severity of renal impairment. Therefore, it is recommended to adjust the dose and dosing intervals of levocetirizine based on creatinine clearance in patients with mild, moderate, or severe renal impairment. In end-stage renal disease patients (CLCR < 10 mL/min) levocetirizine is contraindicated. The amount of levocetirizine removed during a standard 4-hour hemodialysis procedure was <10%.
The dosage of levocetirizine dihydrochloride should be reduced in patients with mild renal impairment. Both the dosage and frequency of administration should be reduced in patients with moderate or severe renal impairment [see Dosage and Administration (2.2) ].
Levocetirizine dihydrochloride has not been studied in patients with hepatic impairment. The non-renal clearance (indicative of hepatic contribution) was found to constitute about 28% of the total body clearance in healthy adult subjects after oral administration.
As levocetirizine is mainly excreted unchanged by the kidney, it is unlikely that the clearance of levocetirizine is significantly decreased in patients with solely hepatic impairment [see Dosage and Administration (2) ].
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