Levocetirizine: pharmacokinetics and pharmacodynamics in children age 6 to 11 years

Is Gender an Important Factor in the Precision Medicine Approach to Levocetirizine?

Currently, there is insufficient information on the variability in levocetirizine pharmacometrics among individuals, a crucial aspect for establishing its clinical use. The gender differences in pharmacokinetics and the extent of variation in pharmacodynamics have not been definitively identified. The primary goal of this study was to investigate gender differences in levocetirizine pharmacokinetics and quantitatively predict and compare how these gender-related pharmacokinetic differences impact pharmacodynamics, using population pharmacokinetic-pharmacodynamic modeling. Bioequivalence results for levocetirizine (only from the control formulation) were obtained from both healthy Korean men and women. Physiological and biochemical parameters for each individual were utilized as pharmacokinetic comparison and modeling data between genders. Pharmacodynamic modeling was performed using reported data on antihistamine responses following levocetirizine exposure. Gender, weight, body surface area, peripheral distribution volume, albumin, central-peripheral inter-compartmental clearance, and the fifth sequential absorption rate constant were explored as effective covariates. A comparison of the model simulation results showed a higher maximum concentration and faster plasma loss in females than in males, resulting in a faster recovery to baseline of the antihistamine effect; however, the absolute differences between genders in the mean values were not large within 10 ng/mL (for plasma concentrations) or % (wheal and flare size changes). Regarding the pharmacokinetics and pharmacodynamics of levocetirizine, the gender effect may not be significant when applying the usual dosage (5 mg/day). This study will be useful for bridging the knowledge gap in scientific precision medicine by introducing previously unconfirmed information regarding gender differences in levocetirizine pharmacometrics.

Biowaiver Monograph for Immediate-Release Solid Oral Dosage Forms: Levocetirizine Dihydrochloride

Levocetirizine, a histamine H1-receptor antagonist, is prescribed to treat uncomplicated skin rashes associated with chronic idiopathic urticaria as well as the symptoms of both seasonal and continual allergic rhinitis. In this monograph, the practicality of using Biopharmaceutics Classification System (BCS) based methodologies as a substitute for pharmacokinetic studies in human volunteers to appraise the bioequivalence of immediate-release (IR) oral, solid dosage forms containing levocetirizine dihydrochloride was investigated, using data from the literature and in-house testing. Levocetirizine's solubility and permeability properties, as well as its dissolution from commercial products, its therapeutic uses, therapeutic index, pharmacokinetics and pharmacodynamic traits, were reviewed in accordance with the BCS, along with any reports in the literature about failure to meet bioequivalence (BE) requirements, bioavailability issues, drug-excipient interactions as well as other relevant information. The data presented in this monograph unequivocally point to classification of levocetirizine in BCS Class 1. For products that are somewhat supra-equivalent or somewhat sub-equivalent, clinical risks are expected to be insignificant in light of levocetirizine's wide therapeutic index and unlikelihood of severe adverse effects. After careful consideration of all the information available, it was concluded that the BCS-based biowaiver can be implemented for products which contain levocetirizine dihydrochloride, provided (a) the test product comprises excipients that are typically found in IR oral, solid drug products that have been approved by a country belonging to or associated with ICH and are used in quantities that are typical for such products, (b) data supporting the BCS-based biowaiver are gathered using ICH-recommended methods, and (c) all in vitro dissolution requirements specified in the ICH guidance are met by both the test and comparator products (in this case, the comparator is the innovator product).

Rupatadine Oral Solution Titration by Body Weight in Paediatric Patients Suffering from Allergic Rhinitis: A Population Pharmacokinetic Study

Background

Allergic rhinitis (AR) and chronic urticaria, both are treated in children with doses of second generation of antihistamines that have been mostly based on extrapolation of data obtained in adults. The objectives of this work were to develop a model to explain the pharmacokinetics (PK) of rupatadine, a second generation antihistamine, administered to children 2−11 years old and to calculate the non-compartmental PK parameters for two groups of age (2–5 and 6–11 years old) based on the individual Bayesian estimates from the selected model.

Methods

Data from two PK studies with rupatadine oral solution (1 mg/mL) were pooled: Study A, an extensive blood sampling study performed in 11 children (6–11 years old) who received a single oral dose of rupatadine; and Study B, a sparse blood sampling study in 40 children (2–5 years old) receiving multiple oral doses. A simultaneous population PK model was developed using data available for all children. Using individual Bayesian estimates from the selected model, steady-state plasma concentrations for both studies were simulated and the non-parametric PK parameters were calculated for two age groups: 2–5 years (subgroup I) and 6–11 years (subgroup II).

Results

A two-compartment model with first-order absorption and elimination with clearance depending on body weight, better described the PK of rupatadine for 2–11 year old children. The plasma clearance dependence on weight was linear. The mean (SD) non-compartment PK parameters calculated using simulated plasma profiles at steady state were: C_max, 2.54 (1.26) vs 1.96 (0.52) ng/mL; AUC_0-24h, 10.74 (3.09) vs 10.38 (4.31) ng/mL/h; and t_1/2, 12.28 (3.09) vs 15.94 (4.09) h, for children 6–11 and 2–5 years old, respectively.

Conclusions

The PK of rupatadine depends on the weight of paediatric patients but not on their age. The dosage strategy adjusted by body weight in children 2–11 years old (2.5 mL if weight 10–25 kg, and 5 mL if ≥ 25 kg) provides similar exposure between the two groups of age, and to that obtained in adults with the 10 mg dose tablet formulation.

The Reliability of Histamine Pharmacodynamic Response Phenotype Classification in Children With Allergic Disease

We have identified distinct histamine pharmacodynamic response phenotypes in children with allergic disease utilizing histamine iontophoresis with laser Doppler (HILD). These response phenotypes may be relevant in guiding therapeutic decision making for agents targeting the allergic response pathways. However, the reliability of these response phenotypes has not been assessed. Therefore, we performed HILD in children with allergic rhinitis and/or asthma on two to three separate occasions. HILD response-time data were analyzed in NONMEM using a linked effect PKPD model. Examination of observed vs. classified response phenotypes predicted response plots and the sum of residuals. The intraclass correlation coefficient (ICC) was used to determine the reliability of phenotype classification. Eighty-two percent of children exhibited a reliable histamine response phenotype [intraclass correlation coefficient 0.77 (95% CI 0.44–0.93]. These preliminary results suggest moderate reliability of HILD response phenotype in children. Further exploration is needed to determine contributions to phenotype variability.

Model-informed pediatric development applied to bilastine: Analysis of the clinical PK data and confirmation of the dose selected for the target population

Bilastine is a non-sedating second-generation H₁ antihistamine approved for treatment of allergic rhinoconjunctivitis (AR) and urticaria (U) in adults at the oral (p.o.) dose of 20 mg once daily (OD). Optimal attributes can be anticipated for its clinical use in pediatrics due to its favorable safety and tolerability and age-independent PD profile. The aim of this work was to characterize bilastine PK in children through population modeling of data from a limited sampling confirmatory clinical trial in children with AR or U. The objective was also to ascertain whether the proposed dose (10 mg/day) in the target pediatric subset aged 2-<12 years matches the systemic exposure seen in adults at the 20 mg/day dose. A popPK model characterizing bilastine PK behavior in children aged from 4 to <12 years treated with 10 mg oral bilastine daily was successfully developed and qualified. No relationship was found between bilastine PK and age or weight; stopping rules pre-stablished to finalize the trial, i.e., model completeness and no dependence of exposure on decreasing age, were thus fulfilled. On a second step, the popPK model in children was linked to the PD model in adults assuming the same PD as described in adults and used to compare the PD outcome between both populations. Finally, an allometric scaling method and a physiological approximation were used to evaluate the suitability of the selected dose in the youngest children, showing that children from 2 years were deemed to belong to the same population as well. The achievement of comparable PK (i.e., within the range) to that observed in adults after the therapeutic dose of 20 mg, together with the achievement of similar PD and additional integrative analysis, served to confirm the validity of the 10 mg daily dose for the target pediatric subset (2 to <12 years).

Model Informed Pediatric Development Applied to Bilastine: Ontogenic PK Model Development, Dose Selection for First Time in Children and PK Study Design

PURPOSE

Bilastine is an H₁ antagonist whose pharmacokinetics (PK) and pharmacodynamics (PD) have been resolved in adults with a therapeutic oral dose of 20 mg/day. Bilastine has favorable characteristics for use in pediatrics but the PK/PD and the optimal dose in children had yet to be clinically explored. The purpose is to: (1) Develop an ontogenic predictive model of bilastine PK linked to the PD in adults by integrating current knowledge; (2) Use the model to design a PK study in children; (3) Confirm the selected dose and the study design through the evaluation of model predictability in the first recruited children; (4) Consider for inclusion the group of younger children (< 6 years).

METHODS

A semi-mechanistic approach was applied to predict bilastine PK in children assuming the same PD as described in adults. The model was used to simulate the time evolution of plasma levels and wheal and flare effects after several doses and design an adaptive PK trial in children that was then confirmed using data from the first recruits by comparing observations with model predictions.

RESULTS

PK/PD simulations supported the selection of 10 mg/day in 2 to <12 year olds. Results from the first interim analysis confirmed the model predictions and design hence trial continuation.

CONCLUSION

The model successfully predicted bilastine PK in pediatrics and optimally assisted the selection of the dose and sampling scheme for the trial in children. The selected dose was considered suitable for younger children and the forthcoming safety study in children aged 2 to <12 years.

Population pharmacokinetic modelling of rupatadine solution in 6-11 year olds and optimisation of the experimental design in younger children

AIMS

To optimise a pharmacokinetic (PK) study design of rupatadine for 2-5 year olds by using a population PK model developed with data from a study in 6-11 year olds. The design optimisation was driven by the need to avoid children's discomfort in the study.

METHODS

PK data from 6-11 year olds with allergic rhinitis available from a previous study were used to construct a population PK model which we used in simulations to assess the dose to administer in a study in 2-5 year olds. In addition, an optimal design approach was used to determine the most appropriate number of sampling groups, sampling days, total samples and sampling times.

RESULTS

A two-compartmental model with first-order absorption and elimination, with clearance dependent on weight adequately described the PK of rupatadine for 6-11 year olds. The dose selected for a trial in 2-5 year olds was 2.5 mg, as it provided a Cmax below the 3 ng/ml threshold. The optimal study design consisted of four groups of children (10 children each), a maximum sampling window of 2 hours in two clinic visits for drawing three samples on day 14 and one on day 28 coinciding with the final examination of the study.

CONCLUSIONS

A PK study design was optimised in order to prioritise avoidance of discomfort for enrolled 2-5 year olds by taking only four blood samples from each child and minimising the length of hospital stays.

Population pharmacokinetic/pharmacodynamic modeling of histamine response measured by histamine iontophoresis laser Doppler

The epicutaneous histamine (EH) test is the current gold standard method for the clinical evaluation of allergic conditions. However, the EH method is limited in providing an objective and qualitative assessment of histamine pharmacodynamic response. The histamine iontophoresis with laser Doppler (HILD) monitoring method, an alternative method, allows a fixed dose of histamine to be delivered and provides an objective, continuous, and dynamic measurement of histamine epicutaneous response in children and adults. However, due to the high sampling frequency (up to 40 Hz), the output files are usually too cumbersome to be directly used for further analysis. In this study, we developed an averaging algorithm that efficiently reduces the HILD data in size. The reduced data was further analyzed and a population linked effect pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the local histamine response. The model consisted of a one-compartment PK model and a direct-response fractional maximum effect (Emax) model. The parameter estimates were obtained as follows: absorption rate constant (ka), 0.094/min; absorption lag time (Tlag), 2.72 min; partitioning clearance from local depot to systemic circulation (CLpar), 0.0006 L/min; baseline effect (E0), 13.1 flux unit; Emax, 13.4; concentration at half maximum effect (EC50) 31.1 mg/L. Covariate analysis indicated that age and race had significant influence on Tlag and EC50, respectively.

An overview of the pediatric medications for the symptomatic treatment of allergic rhinitis, cough, and cold

Upper respiratory infections and allergic rhinitis are common diseases in children. In recent years, U.S. Food and Drug Administration has been promoting pediatric drug development with marketing exclusivity incentives and requirements. The assessment of clinical pharmacology, efficacy, and safety data has facilitated pediatric drug development and provided appropriate labeling for pediatric use. Regulatory decision making involves multiple evaluation processes, including drug exposure comparison between adult and pediatric population, formulation bridging, dose selection, and evaluation of efficacy and safety in pediatric patients. This article reviews the pediatric drugs indicated for cough, cold, and allergic rhinitis, focusing on the utility of clinical pharmacology, safety, and efficacy data in determining the pediatric dosing regimen and the approaches taken for regulatory decision making.

Pharmacology of antihistamines

H1-antihistamines, the mainstay of treatment for urticaria, were developed from anticholinergic drugs more than 70 years ago. They act as inverse agonists rather than antagonists of histamine H1-receptors which are members of the G-protein family. The older first generation H1-antihistamines penetrate readily into the brain to cause sedation, drowsiness, fatigue and impaired concentration and memory causing detrimental effects on learning and examination performance in children and on impairment of the ability of adults to work and drive. Their use should be discouraged. The newer second-generation H1-antihistamines are safer, cause less sedation and are more efficacious. Three drugs widely used for symptomatic relief in urticaria, desloratadine, levocetirizine and fexofenadine are highlighted in this review. Of these levocetirizine and fexofenadine are the most potent in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals, whereas fexofenadine has a relatively short duration of action and may be required to be given twice daily for all round daily protection. Although desloratadine is less potent, it has the advantages of rarely causing somnolence and having a long duration of action.

H(1)-antihistamines and urticaria: how can we predict the best drug for our patient?

Urticaria, and especially chronic spontaneous urticaria (CSU), is a difficult condition to treat. Consequently, clinicians need to use the best H(1)-antihistamines currently available and the pharmaceutical industries need to keep developing H(1)-antihistamines that are more effective than the ones we have today. To do this we need to be able to compare the clinical efficacy of both established and new drugs. Obviously, the ideal way to do this is to use head-to-head studies in CSU. However, such studies are extremely expensive and, in the case of novel molecules, have ethical and logistical problems. Consequently, we need to have predictive models. Although determination of Ki, an indicator of the in vitro potency of an H(1)-antihistamine, may help in the initial selection of candidate molecules, the large differences in volume of distribution and tissue accumulation in humans, precludes this from being a good predictor of clinical efficacy in CSU. From the data reviewed in this article, especially the direct comparative data of desloratadine and levocetirizine in weal and flare studies and CSU, weal and flare response would appear to be the best indicator we have of effectiveness of H(1)-antihistamines in clinical practice. However, it must be pointed out that the conclusion is, essentially, based on detailed comparisons of two drugs in studies sponsored by pharmaceutical companies. Consequently, to confirm the conclusions of this review, a multicentre study independent from the influence of pharmaceutical companies should be commissioned to compare the speed of onset and effectiveness of desloratadine, fexofenadine and levocetirizine in chronic spontaneous urticaria and against histamine-induced weal and flare responses in the same patients so that we have a clear understanding of the predictive value of our models.

Antihistamine therapy in allergic rhinitis

Antihistamines have long been a mainstay in the therapy for allergic rhinitis. Many different oral antihistamines are available for use, and they are classified as first generation or second generation based on their pharmacologic properties and side-effect profiles. The recent introduction of intranasal antihistamines has further expanded the role of antihistamines in the treatment of allergic rhinitis. Certain patient populations, such as children and pregnant or lactating women, require special consideration regarding antihistamine choice and dosing as part of rhinitis therapy.

Levocetirizine for the treatment of allergic rhinitis and chronic idiopathic urticaria in adults and children

BACKGROUND

Levocetirizine (LCZ) is a second-generation antihistamine that was approved in January 2008 for the relief of symptoms of seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR), and chronic idiopathic urticaria (CIU) in adults and children aged > or = 6 years.

OBJECTIVES

This article reviews the available literature on the pharmacokinetics and pharmacodynamics, clinical efficacy and tolerability, and effect on quality of life (QoL) of LCZ.

METHODS

A search of the English-language literature was performed using the following databases: MEDLINE (1966-February 2009), International Pharmaceutical Abstracts (19 70-February 2009), Database of Abstracts of Reviews of Effectiveness, Cochrane Database of Systematic Reviews, EMBASE Drugs & Pharmacology (1991-February 2009), Blackwell Synergy, CINAHL Plus with Full Text, EBSCOhost, ScienceDirect, and Wiley Interscience. The search terms were levocetirizine, allergic rhinitis, chronic idiopathic urticaria, antihistamine, pharmacokinetics, quality of life, drug interactions, case reports, and cost. Publications describing studies of > or = 2 weeks' duration that concerned the efficacy, tolerability, pharmacoeconomics, and/or QoL effects of LCZ were included in the review.

RESULTS

In 4 studies in adult patients with moderate to severe PAR, LCZ 5 mg/d was associated with significant improvements in symptom scores for sneezing, rhinorrhea, and ocular/nasal pruritus at 4 to 6 weeks compared with placebo (P < or = 0.05). In 3 studies, nasal congestion scores were significantly improved within 4 to 6 weeks compared with placebo (P < 0.001). LCZ 5 mg/d was associated with improvements compared with placebo in scores for the ability to do housework, complete work activities, and engage in outdoor activities at 6 months (P < or = 0.011). In a 6-week study in children with moderate to severe SAR, LCZ 5 mg/d was associated with significant improvements compared with placebo in sneezing, rhin-orrhea, and itchy nose (P < 0.004); significant improvements in symptoms from baseline were also seen in a 4-week study in adults with SAR (P < 0.001). One study in patients with SAR reported no significant difference between LCZ and fluticasone compared with fluticasone monotherapy in terms of improvement in QoL, nasal airflow obstruction, sneezing, or pruritus. In a 6-week study in patients with moderate to severe CIU, LCZ 5 mg/d was significantly more effective than placebo in reducing overall CIU symptoms (P < 0.05). In two 4-week studies, one comparing LCZ 5 mg/d with placebo and the other comparing it with desloratadine (DSL), LCZ was significantly more effective than either comparator in terms of improvement in scores for pruritus severity (P < or = 0.001 vs placebo; P < 0.004 vs DSL) and duration (P < or = 0.001 vs placebo; P = 0.009 vs DSL). LCZ was significantly more effective than placebo (but not DSL) in reducing the number and size of wheals (both, P = 0.001). In a 12-week, open-label, crossover study, patients reported significantly longer symptom relief with cetirizine than LCZ (P < 0.005). The most commonly reported adverse events in two 6-month studies in adults with PAR treated with LCZ 5 mg/d included headache (23.8%), pharyngitis (19.4%), influenza (14.6%), fatigue (8.3%), and somnolence (8.3%). There is serious concern about the possibility of febrile seizures in infants treated with LCZ. Three pharmacoeconomic studies of LCZ 5 mg/d were identified, one comparing it with placebo in patients with PAR, one comparing it with placebo in patients with CIU, and another comparing it with second-generation antihistamines and montelukast in patients with PAR. Because of design limitations and differences in comparators in these studies, it was not possible to determine the cost-effectiveness of LCZ in the treatment of PAR or CIU.

CONCLUSIONS

In the studies reviewed, LCZ 5 mg/d was effective in reducing symptoms of PAR, SAR, and CIU and improving QoL, with an acceptable tolerabili-ty profile. There is a need for studies of longer durations, head-to-head comparisons against other anti-histamines, drug-interaction studies, safety studies in infants, and cost-effectiveness analyses.

Pharmacokinetics in special populations

Pharmacokinetics are typically dependent on a variety of physiological variables (e.g., age, ethnicity, or pregnancy) or pathological conditions (e.g., renal and hepatic insufficiency, cardiac dysfunction, obesity, etc.). The influence of some of these conditions has not always been thoroughly assessed in the clinical studies of antiallergic drugs. However, the knowledge of the physiological grounds of the pharmacokinetics can provide some insight for predicting the potential alterations and guiding the initial prescription strategies. It is important to recognize that both pharmacokinetic and pharmacodynamic differences between populations should be considered. The available information on drugs used for the therapy of allergic diseases is reviewed in this chapter.

Study on the interaction of levocetirizine dihydrochloride with human serum albumin by molecular spectroscopy

The interaction between cetirizine dihydrochloride and human serum albumin (HSA) has been examined by the spectroscopic techniques first. According to Stern-Volmer equation at different temperatures and the UV-vis spectra examination it was demonstrated that HSA fluorescence quenching initiated by levocetirizine was static. The values of binding constant (K(A)) and the number of binding sites (n) for levocetirizine and HSA were smaller than those for cetirizine and HSA, which meant that the transport of drug was regulated by the stereoselectivity of HSA to the enantiomer. The effect of the non-enzymatic glycosylation (NEG) on the interaction between levocetirizine and HSA signified that the administration of levocetirizine for diabetes should be different from the normal. The positive DeltaS(o) and negative DeltaH(o) indicated that ionic interaction played a major role between levocetirizine and HSA. Circular dichroism (CD) measurement showed that the secondary structure of HSA has changed in the presence of levocetirizine, and alpha-helical content decreased from 63.1% for free HSA to 54.9% for combined HSA, and accordingly the other secondary structure (beta-strand, beta-turns and others) contents increased to some extent. Finally, by the competitive binding experiments it was deduced that levocetirizine specifically bound to HSA in the region of site II, which meant the curative effect of levocetirizine should be reconsidered when it was administrated together with other site II drugs.

Effects of sedative and nonsedative antihistamines on prefrontal activity during verbal fluency task in young children: a near-infrared spectroscopy (NIRS) study

INTRODUCTION

Antagonists of histamine H(1) receptors (antihistamines) are widely used for the treatment of allergic disorders in children. These drugs' sedative effect on brain function, however, has been mostly examined in adults.

OBJECTIVE

The objective of this study was to examine the effects of anitihistamines on prefrontal cortex activity in young children using near-infrared spectroscopy (NIRS), a novel brain-imaging method.

MATERIALS AND METHODS

In 15 healthy children (mean age, 7.7 years), we examined changes of oxygenated hemoglobin concentration in the prefrontal cortex while they performed a verbal fluency task 3 h after taking a sedating antihistamine (ketotifen), nonsedating antihistamine (epinastine), or placebo.

RESULTS

Ketotifen significantly impaired behavioral performance and cortical activation at the lateral prefrontal cortex compared with placebo. There were no sedative effects on neural response or behavioral performance after epinastine administration.

CONCLUSIONS

NIRS revealed that sedating and nonsedating antihistamines exert differential effects on brain hemodynamic response in young children.

The comparison of cetirizine, levocetirizine and placebo for the treatment of childhood perennial allergic rhinitis

Cetirizine (Zyrtec) is a potent and long-acting second-generation histamine H1- receptor antagonist for the treatment of allergic disease, such as allergic rhinitis and chronic idiopathic urticaria, in adult and child. It is a racemic mixture of levocetirizine (Xyzal) and dextrocetirizine. The purpose of this present study was to compare the efficacy of cetirizine, levocetirizine and placebo for the treatment of pediatric perennial allergic rhinitis. 74 perennial allergic rhinitis patients, aged 6 to 12 years old, assigned to 1 of 3 treatment groups for 12 weeks randomly. The effects of the three agents were compared with the Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ) and Total Symptom Score (TSS) by diary. Nasal peak expiratory flow rate (nPEFR) and laboratory examinations including serum immunoglobulin E level, eosinophil cationic protein (ECP), blood eosinophil counts and eosinophil percentage in a nasal smear were evaluated among the three groups. The results revealed that both cetirizine and levocetirizine improved TSS in comparison with the placebo group, and ceterizine appeared to be more efficacious than levocetirizine at week 8 and week 12. The PRQLQ score showed significant decreased both in cetirizine and levocetirizine group, but there was no statistic significant difference between both groups. The eosinophil proportion in a nasal smear significantly decreased among the cetirizine in comparison with the placebo group but there was no statistic significant in levocetirizine groups. Both cetirizine and levocetirizine showed significant improvement in nPEFR in comparison with the placebo group, and ceterizine appeared to be more efficacious than levocetirizine. The 12-week treatment program showed that cetirizine was more effectious than levocetirizine.

New oral H1 antihistamines in children: facts and unmeet needs

BACKGROUND

Second-generation antihistamines differ from first-generation ones because of their elevated specificity and affinity for peripheral H1-receptors and because of their lower penetration to the central nervous system, having fewer sedative effects as a result. Over the last few years, new compounds with different pharmacokinetic properties have been synthesized. More recent improvements of the molecules, generally in the form of active metabolites, led to the synthesis of new-generation antihistamines.

METHODS

Recommendations on the minimum criteria that would have to be met for compounds to be classified as new-generation antihistamines have been recently established by a consensus statement. In the past, the pharmacokinetics and pharmacodynamics of H1 antihistamines have not been optimally investigated in the pediatric population, especially in infants and young children.

RESULTS

The pharmacology of second-generation H1 antihistamines has been investigated relatively deeper than old antihistamines in children. In the pediatric population, clinical studies with new-generation antihistamines are still limited in number and, with rare exceptions, of brief duration. Comparative trials on the efficacy and safety between different compounds are also lacking.

CONCLUSIONS

Properly designed, long-term trials with new-generation H1 antihistamines need to be performed in single age groups, in order to better define the effects of these drugs in all pediatric population.

A review of the role of levocetirizine as an effective therapy for allergic disease

BACKGROUND

Levocetirizine is the R-enantiomer of cetirizine dihydrochloride with pharmacodynamically and pharmacokinetically favourable characteristics.

OBJECTIVE

To review the evidence that levocetirizine is an effective therapy for allergic disease.

METHODOLOGY

Relevant articles in English or with English abstracts were identified from systematic PubMed searches.

RESULTS

Levocetirizine has high bioavailability, high affinity for and occupancy of the H1 receptor, rapid onset of action, limited distribution and minimal hepatic metabolism. Clinical trials indicate that it is safe and effective for the treatment of allergic rhinitis and chronic idiopathic urticaria in adults and children with a minimal number of untoward effects. It is also becoming clearer that, in addition to its being a potent antihistamine, levocetirizine has several anti-inflammatory effects that are observed at clinically relevant concentrations that may enhance its therapeutic benefit. Furthermore, there appears to be a growing trend for the use of levocetirizine as long-term therapy in addition to it being used as a treatment for the immediate short-term manifestations of allergic disease.

CONCLUSION

Levocetirizine is an effective and safe treatment for use in adults and children with allergic disease.

Evolving paradigm in the management of allergic rhinitis-associated ocular symptoms: role of intranasal corticosteroids

BACKGROUND

Along with nasal symptoms, ocular symptoms such as itching, tearing, and redness are common, bothersome components of the allergic rhinitis (AR) profile. Treatment of the patient with ocular allergy symptoms should take into account a variety of factors, including severity of symptoms, convenience/compliance issues, and patient preferences.

OBJECTIVES

To review from the primary care perspective the epidemiology, pathophysiology, and management of ocular symptoms associated with AR, and to evaluate the emerging role of intranasal corticosteroids (INSs).

FINDINGS

A search of the PubMed database identified clinical trials that assessed efficacy of agents in reducing ocular allergy symptoms. Internet searches identified further information including data on over-the-counter agents for treatment of ocular symptoms. Searches were conducted using search terms such as pathophysiology, epidemiology, ocular allergy, quality of life, drug class, and drug names. Primary care physicians are often the first point of contact for patients with seasonal AR (SAR) or perennial AR (PAR) symptoms. Ocular allergy associated with SAR and PAR (seasonal and perennial allergic conjunctivitis, respectively) is characterized by both early- and late-phase reactions, with symptoms often persisting long after allergen exposure. Non-pharmacologic measures such as allergen avoidance, use of artificial tears, and cool compresses are pertinent for all ocular allergy sufferers, but may not afford adequate symptom control. Pharmacotherapy options have traditionally included topical ophthalmic products for cases of isolated ocular symptoms, and oral antihistamines for patients with both nasal and ocular symptoms. However, this paradigm is changing with new evidence regarding the efficacy of INSs in reducing ocular symptoms. A number of meta-analyses and individual studies, most of which studied ocular symptoms as secondary variables, have demonstrated the ocular effects of INSs versus topical and oral antihistamines. Additional prospective studies on this topic are encouraged to provide further evidence for these findings.

CONCLUSIONS

In light of their well-established efficacy in reducing nasal allergy symptoms, INSs offer a comprehensive treatment option in patients with nasal and ocular symptoms. Oral antihistamines and/or topical eye drops may also be necessary depending on symptom control.

H1-antihistamine treatment in young atopic children: effect on urticaria

BACKGROUND

There are few published, randomized, double-masked, placebo-controlled, clinical trials of interventions for urticaria in the pediatric population.

OBJECTIVE

To study the effect of long-term treatment with the H1-antihistamine levocetirizine on urticaria in young atopic children.

METHODS

In the randomized, double-masked, parallel-group Early Prevention of Asthma in Atopic Children Study, children with atopic dermatitis aged 12 to 24 months at enrollment received levocetirizine, 0.125 mg/kg, or matching placebo twice daily for 18 months. On a diary card, the child's caregiver recorded the days on which urticaria was observed. This was validated by the study investigator and entered into the electronic case report form, along with any additional relevant information.

RESULTS

A total of 510 atopic children (mean +/- SEM age, 19.4 +/- 0.2 months) composed the intention-to-treat population. During the subsequent 18 months, 27.5% (70/255) of the children taking levocetirizine and 41.6% (106/255) of the children taking placebo experienced urticaria (P < .001). The mean +/- SEM number of urticaria episodes was 0.71 +/- 0.11 in those receiving levocetirizine and 1.71 +/- 0.25 in those receiving placebo (P < .001). The mean +/- SEM duration of urticaria episodes was 4.43 +/- 1.57 days in those receiving levocetirizine and 5.36 +/- 1.27 days in those receiving placebo (P < .001).

CONCLUSIONS

Urticaria is common in atopic toddlers and deserves recognition as an important disorder that occurs early in the atopic marathon. Regular long-term treatment with levocetirizine effectively prevents and treats urticaria in young children. The results of this study strengthen the evidence base for the use of relatively nonsedating, second-generation H1-antihistamines in the pediatric population.

Safety of levocetirizine treatment in young atopic children: An 18-month study

There are more than 40 H(1)-antihistamines available worldwide. Most of these medications have never been optimally studied in prospective, randomized, double-masked, placebo-controlled trials in children. The aim was to perform a long-term study of levocetirizine safety in young atopic children. In the randomized, double-masked Early Prevention of Asthma in Atopic Children Study, 510 atopic children who were age 12-24 months at entry received either levocetirizine 0.125 mg/kg or placebo twice daily for 18 months. Safety was assessed by: reporting of adverse events, numbers of children discontinuing the study because of adverse events, height and body mass measurements, assessment of developmental milestones, and hematology and biochemistry tests. The population evaluated for safety consisted of 255 children given levocetirizine and 255 children given placebo. The treatment groups were similar demographically, and with regard to number of children with: one or more adverse events (levocetirizine, 96.9%; placebo, 95.7%); serious adverse events (levocetirizine, 12.2%; placebo, 14.5%); medication-attributed adverse events (levocetirizine, 5.1%; placebo, 6.3%); and adverse events that led to permanent discontinuation of study medication (levocetirizine, 2.0%; placebo, 1.2%). The most frequent adverse events related to: upper respiratory tract infections, transient gastroenteritis symptoms, or exacerbations of allergic diseases. There were no significant differences between the treatment groups in height, mass, attainment of developmental milestones, and hematology and biochemistry tests. The long-term safety of levocetirizine has been confirmed in young atopic children.

Levocetirizine: a review of its use in the management of allergic rhinitis and skin allergies

Levocetirizine (Xyzal) is a selective, potent, oral histamine H(1) receptor antagonist of the latest generation that is licensed for the symptomatic treatment of allergic rhinitis (including persistent allergic rhinitis [PER]) and chronic idiopathic urticaria (CIU). Large, well designed trials indicate that levocetirizine is effective and generally well tolerated in the treatment of allergic rhinitis and CIU. Its pharmacological profile offers many positive aspects: a rapid onset and long duration of antihistaminic effect; rapid absorption and high bioavailability; a low potential for drug interactions; a low volume of distribution; and a lack of effect on cognition, psychomotor function and the cardiovascular system. Allergen challenge chamber studies suggest that levocetirizine has better efficacy than desloratadine, loratadine or fexofenadine. Well controlled, long-term studies with other later-generation H(1) receptor antagonists are required to fully define its clinical profile relative to other agents in this class. Overall, levocetirizine is a valuable addition to the oral H(1) receptor antagonists available for the treatment of allergic rhinitis and as first-line therapy in patients with CIU.

Advances in upper airway diseases and allergen immunotherapy

The purpose of this review is to highlight important articles on upper airway disease and immunotherapy that appeared in the Journal of Allergy and Clinical Immunology and elsewhere during 2005. In recent studies of tissue from patients with chronic hypertrophic eosinophilic sinusitis, increased leukotriene C4 synthase and 5-lipoxygenase activity and increased levels of cysteinyl leukotriene production were demonstrated that correlated with disease severity but not with whether the patient was aspirin sensitive. However, the cysteinyl leukotriene 1 receptor was increased in leukocytes in the sinus tissue only in those patients with aspirin sensitivity. Major basic protein, released by eosinophils into the mucus in the paranasal sinus lumen, was found to reach concentrations capable of damaging the sinus epithelium, predisposing to bacterial infections. Testing the hypothesis that chronic hypertrophic eosinophilic sinusitis represents a reaction to common fungi, a double-blind trial of intranasal instillation of amphotericin B was conducted. There were marginal but significant differences in favor of amphotericin B treatment for sinus mucosal thickening on the basis of computed tomography and the evidence of eosinophilic inflammation in the sinus mucus. The effectiveness of topical nasal corticosteroids for treatment of nasal polyps was confirmed in 2 large studies. Improvement in sleep quality and daytime drowsiness in patients with allergic rhinitis treated with nasal corticosteroids was reported to correlate with reduction in nasal obstruction. The statistical analysis behind studies that reported a decrease in asthma exacerbations with nasal corticosteroids or oral antihistamines has been questioned. It appears that the results of at least one of these studies are indeed too good to be true. Although caution is still indicated in administering immunotherapy to patients receiving beta-adrenergic blocking agents, the prohibition might not be absolute. A study in patients with Hymenoptera sensitivity given venom immunotherapy revealed no increase in serious adverse reactions to venom injections and no greater incidence of reactions to insect stings in those taking beta-blocking agents. Sublingual immunotherapy for 8 to 12 weeks in patients with hazelnut sensitivity significantly increased their tolerance to hazelnut in double-blind, placebo-controlled challenges while inducing increased IgG4 and IL-10 levels, indicating induction of regulatory T cells. There were a number of articles in the Journal of Allergy and Clinical Immunology in 2005 that addressed the entity of chronic hypertrophic eosinophilic sinusitis. In addition, an update of the "Practice parameters on sinusitis" was published. The major focus in allergen immunotherapy continues to be sublingual administration.