Cardiovascular safety of fexofenadine HCl

Twenty-five years: The fexofenadine clinical experience

Allergic rhinitis (AR) and urticaria affect a sizable portion of the population worldwide, resulting in reduced quality-of-life and productivity and increased healthcare costs. Fexofenadine (FEX) is a non-sedating second-generation H1 antihistamine with pronounced efficacy and a very good safety profile, used for the treatment of allergic diseases. In addition to its antihistaminic properties, FEX also has anti-inflammatory effects. FEX has a wide therapeutic window and is not associated with any sedative effects, even at higher than recommended doses. There is a need for an integrated management system for AR and urticaria which includes safe and effective treatment options. An ideal anti-allergic formulation should provide fast relief of symptoms and long-lasting effect without drowsiness. Data from randomized clinical trials show that FEX meets these criteria and is an effective treatment option with a favourable safety profile, improving the quality of life of patients suffering from AR and urticaria.

Insights into urticaria in pediatric and adult populations and its management with fexofenadine hydrochloride

OBJECTIVE

The present narrative review provides a comprehensive update of the current knowledge on urticaria, both in adult and pediatric populations, and on the safety and efficacy of fexofenadine hydrochloride (HCl) as a treatment option.

DATA SOURCE

A literature search was conducted on Embase and Medline.

STUDY SELECTION

Clinical studies published in English and published between 1999 and 2020 were selected.

RESULTS

Although the exact pathogenesis of urticaria is not fully understood, multiple pathways of mast cell activation are discussed to explain the existence of phenotypically different clinical manifestations of urticaria. An overview of the worldwide prevalence of chronic urticaria, including disease burden and patient's quality of life is provided. The impact of urticaria on patient's life differs on the basis of whether its form is acute or chronic, but pharmacological approaches are most often needed to control the disabling symptoms. A summary of the current management of urticaria recommended by different guidelines across countries (Global; European; American; Australian; Asian; Japanese) is presented. Non-sedating, second-generation H₁-antihistamines are the preferred choice of treatment across several guidelines worldwide. Herein, the efficacy and safety of fexofenadine HCl, a representative second-generation H₁-antihistamine approved for the treatment of urticaria, is discussed. The occurrence of urticaria manifestations in COVID-19 patients is also briefly presented.

CONCLUSION

The burden of acute and chronic urticaria is high for patients. Second generation anti-histamines such as fexofenadine HCl can help managing the symptoms.

Fexofenadine: review of safety, efficacy and unmet needs in children with allergic rhinitis

Allergic rhinitis (AR) is the most common undiagnosed chronic condition in children. Moderate/severe AR symptoms significantly impair quality of life, and cause sleep disruption, absenteeism and decreased productivity. Additionally, untreated AR predisposes children to asthma and other chronic conditions. Although intranasal corticosteroids are the most effective pharmacologic treatment for AR, oral antihistamines are often preferred. First-generation antihistamines may be chosen to relieve AR symptoms as they are inexpensive and widely available; however, they cause sedative and cardiovascular negative effects due to poor receptor selectivity. Therefore, second-generation antihistamines were developed to reduce adverse effects while retaining efficacy. There are fewer clinical trials in children than adults, therefore, efficacy and safety data is limited, particularly in children under 6 years, highlighting the need to generate these data in young children with AR. Fexofenadine, a highly selective second-generation antihistamine, effectively alleviates symptoms of AR, is non-sedating due to decreased blood-brain barrier permeability, and is devoid of cardiovascular side effects. Importantly, fexofenadine relieves the ocular symptoms of allergic conjunctivitis, which occur concomitantly with AR, improving quality of life. Overall, fexofenadine displays a favorable safety profile and results in greater treatment satisfaction in children compared with other second-generation antihistamines. This review aimed to evaluate and compare the safety and efficacy of fexofenadine with other available first- and second-generation antihistamines in children with AR.

Management of anaphylaxis and allergies in patients with long QT syndrome: A review of the current evidence

OBJECTIVE

To develop a treatment algorithm for patients with long QT syndrome (LQTS) in case they need antiallergic medications for allergic reactions, including asthma and anaphylaxis.

DATA SOURCES

A literature review was performed to assess safety and to develop antiallergic treatment strategies for patients with LQTS.

STUDY SELECTIONS

LQTS is a heterogeneous group of myocardial repolarization disorders characterized by prolongation of the QT interval that potentially results in life-threatening torsades de pointes tachycardia. Data on pharmacologic treatment in case of anaphylaxis in LQTS are sparse. For this narrative review, all currently available articles on the use of antiallergic drugs for allergic reactions, anaphylaxis, and asthma in patients with LQTS were used.

RESULTS

Local allergic symptoms can be safely treated primarily with fexofenadine, levocetirizine, desloratadine, or cetirizine and, if needed, a short course of corticosteroids. In case of systemic symptoms, epinephrine should be administered. It may be less effective in patients with LQTS treated with β-blockers, necessitating the use of glucagon as add-on treatment. In case of lower airway obstruction, ipratropium bromide should be used, but if not effective, inhaled β₂-adrenergic agents may be used. Continuous cardiac monitoring is indicated with the use of epinephrine and inhaled β₂-adrenergic agents. The use of the latter also warrants intense monitoring of serum potassium levels. Clemastine and dimetindene should be avoided in patients with LQTS.

CONCLUSION

Patients with LQTS have a higher risk of life-threatening complications during the treatment of their allergic reactions because of the underlying disease and concomitant treatment with β-blockers. Treatment algorithms will certainly decrease these complications.

Pharmacotherapy of mast cell disorders

PURPOSE OF REVIEW

Mast cell disorders (MCDs) comprise mastocytosis and disorders referred to as mast cell activation syndrome and are caused by abnormal accumulation and/or activation of mast cells in tissues. Clinical signs and symptoms are protean; therefore, finding suitable treatment options for individual patients entails a challenge for clinicians. The purpose of this manuscript is to review the literature on the available therapeutic interventions in patients with MCD.

RECENT FINDINGS

Pharmacotherapy is mainly directed against the effects of mast cells and their mediators. The current recommendations are exclusively based on expert opinions due to the lack of controlled clinical trials. The targeted therapies aiming at blocking mutant KIT variants and/or downstream signaling pathways are currently being developed and may be considered in severely affected, therapy-refractory patients.

SUMMARY

There is currently no method for predicting the best available approach to control symptoms in individual patients with MCD. Therefore, a stepwise, individual-based approach in pharmacotherapy options appears to be most successful strategy and is recommended in all patients. The core component of the treatment in most patients is to control symptoms caused by mast cell mediator release, whereas cytoreductive therapies are mainly reserved for patients with advanced/aggressive systemic mastocytosis.

Consensus Statement for the Diagnosis and Treatment of Urticaria: A 2017 Update

This article is developed by the Skin Allergy Research Society of India for an updated evidence-based consensus statement for the management of urticaria, with a special reference to the Indian context. This guideline includes updated definition, causes, classification, and management of urticaria. Urticaria has a profound impact on the quality of life and causes immense distress to patients, necessitating effective treatment. One approach to manage urticaria is by identification and elimination of the underlying cause(s) and/or eliciting trigger(s) while the second one is by treatment for providing symptomatic relief. This guideline recommends the use of second-generation nonsedating H1-antihistamines as the first-line treatment. The dose can be increased up to four times to meet the expected results. In case patients still do not respond, appropriate treatment options can be selected depending on the associated medical condition, severity of the symptoms, affordability of the drugs, and accessibility of modern biologics such as omalizumab.

Prolonged Qt Interval after Fexofenadine Overdose in the Presence of Hypokalemia and Hypocalcaemia

A 23-year-old healthy woman was admitted to our emergency department because of syncope and unconsciousness. She had taken 20 tablets of fexofenadine (total 2400 mg) and 9 tablets of furosemide (total 360 mg) for suicide. The electrocardiogram demonstrated bradycardia (48/min) and markedly prolonged QTc interval (684 msec). Endotracheal intubation and nasogastric tube insertion were performed. Gastric lavage was implemented and activated charcoal was given. A transient pacemaker was implanted. Hypokalemia and hypocalcaemia were also present and the electrolyte disturbances were corrected. The heart rate and QTc interval returned to normal limits after treatment. She stayed in our hospital for seven days. She recovered completely and ventricular arrhythmia was not seen during the hospitalization period.

Optimal Duration of Allergic Rhinitis Clinical Trials

OBJECTIVE: Guidelines have been published by the Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products (EMEA) for the conduct of seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR) studies. These guidelines have differences regarding the duration of such trials: the FDA suggests 2 weeks for SAR and 4 weeks for PAR but the EMEA suggests 2 to 4 weeks for SAR and 6 to 12 weeks for PAR trials. In the interest of global harmonization, it would be desirable to have a uniform duration of such trials so that investigators, internationally, would be able to readily compare results for various types of treatments based on a single standard. Therefore, we performed an evidence-based review to answer the clinical question, What is the optimal duration for SAR and PAR clinical trials?

METHODS: We performed a MEDLINE search of the published literature from 1995 to the present. We used appropriate search terms, such as allergic rhinitis, seasonal allergic rhinitis, perennial allergic rhinitis, SAR, and PAR, to identify pertinent articles. These articles were reviewed and graded according to the evidence quality.

RESULTS: After an initial screening of more than 300 articles, 138 articles were analyzed thoroughly. No study specifically addressed the question of the optimal duration of SAR or PAR clinical trials.

CONCLUSIONS: We conclude that the current FDA (draft) guidelines calling for a study length of 2 weeks for the assessment of drug efficacy for SAR and 4 weeks for the study of drug efficacy in PAR are appropriate and that longer study periods are not likely to add meaningfully to the assessment of drug efficacy.

Laminar ventricular myocardium on a microelectrode array-based chip

Pharmaceutical screening based on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and multi electrode arrays (MEAs) have been proposed as a complementary method for electrophysiological safety and efficacy assessment in drug discovery and development. Contrary to animal models, these cells offer a human genetic background but, at present, fail to recapitulate the mechanical and structural properties of the native human myocardium. Here, we report that topographical cues on soft micromolded gelatin can coax hiPSC-CMs to form laminar cardiac tissues that resemble the native architecture of the heart. Importantly, using this method we were able to record tissue-level electrophysiological responses with a commercially available MEA setup. To validate this platform, we recorded cardiac field potentials at baseline and after pharmacological interventions with a β-adrenergic agonist (isoproterenol). Further, we tested the ability of our system to predict the response of laminar human cardiac tissues to a cardiotoxic pro-drug (terfenadine) and its non-cardiotoxic metabolite (fexofenadine). Finally, we integrated our platform with microfluidic components to build a heart-on-a-chip system that can be fluidically linked with other organs-on-chips in the future.

Cardiovascular safety of antihistamines

Histamine is a mediator, which increases the permeability of capillaries during the early phase of allergic reaction, causes smooth muscle contraction of bronchi and stimulates mucous glands in the nasal cavity. Antihistamines are the basis of symptomatic treatment in the majority of allergic diseases, especially allergic rhinitis, allergic conjunctivitis, urticaria and anaphylaxis. The cardiotoxic effects of the two withdrawn drugs, terfenadine and astemizole, were manifested by prolonged QT intervals and triggering torsades de pointes (TdP) caused by blockade of the ‘rapid’ I_Kr potassium channels. These phenomena, however, are not a class effect. This review deals with a new generation of antihistamine drugs in the context of QT interval prolongation risk.

QTc interval prolongation by fexofenadine in healthy human volunteers and its correlation with plasma levels of fexofenadine: A demonstration of anticlockwise hysteresis

Aim:

The study was designed to establish relationship between the plasma concentration and QTc interval prolonging effect of fexofenadine and demonstrate the phenomenon of anticlockwise hysteresis.

Materials and Methods:

Six subjects were given fexofenadine 60 mg tablet orally under stable conditions, and their drug concentrations were measured at regular intervals. At predetermined time, their ECGs were recorded. Data were analyzed and plotted graphically.

Design and Setting:

Randomized parallel design, single group study conducted at clinical research organization of Ahmadabad.

Results:

In all subjects time taken for maximum plasma concentration of fexofenadine (T_max) was around 3 h and the value of average maximum plasma concentration was 460.63 ng/mL, the effect of fexofenadine on the heart (measured as QTc interval prolongation) was maximum (E_max) after 6 h and average QTc interval was 469.75 ms. Thus, the time to maximum concentration of fexofenadine did not match with the maximum effect on the heart as measured by QTc interval.

Conclusion:

The relationship between the drug concentration and drug effect on the heart are at two different time scales. It can be understood by two-compartment model of pharmacokinetics, and this retardation or lagging of an effect behind the concentration is known as hysteresis. The increase of QTc was not beyond 500 ms and not sustained, demonstrating overall cardiac safety of fexofenadine.

Fexofenadine: biochemical, pharmacokinetic and pharmacodynamic properties and its unique role in allergic disorders

BACKGROUND

Fexofenadine is one of several second-generation H(1)-antihistamines approved for the treatment of various allergic disorders; however, it shows numerous unique properties that make it an optimal choice for many patients.

OBJECTIVE

To review the pharmacology, efficacy and safety of fexofenadine and the attributes differentiating it from other H(1)-antihistamines.

METHODS

We performed a literature search in PubMed/MEDLINE (1966 - March 2009) using the keywords fexofenadine, antihistamine, allergic rhinitis and chronic urticaria. We also reviewed data provided by the manufacturer in addition to reports from various governmental agencies.

RESULTS/CONCLUSIONS

Fexofenadine is devoid of sedative and anticholinergic effects and may offer equivalent or greater efficacy in treating allergic disorders compared with other currently available second-generation H(1)-antihistamines. In addition, fexofenadine may offer cost savings over other selected H(1)-antihistamines owing to its recent availability in generic form in the US.

QTc prolongation assessment in anticancer drug development: clinical and methodological issues

Cardiac safety assessments are commonly employed in the clinical development of investigational oncology medications. In anti-cancer drug development there has been increasing consideration for the potential of a compound to cause adverse electrocardiographic changes, especially QT interval prolongation, which can be associated with risk of torsades de pointes and sudden death. Irrespective of overt clinical toxicities, QTc assessment can potentially influence decision making at many levels during the conduct of clinical studies, including eligibility for protocol therapy, dose delivery or discontinuation, and analyses of optimal dose for subsequent development. Given the potential for serious and irreversible morbidity from cardiac adverse events, it is understandable that cardiac safety results can have broad impact on study conduct and patient management. The methodologies for risk management of QTc prolongation for non cardiac drugs have been developed out of experiences primarily from drugs used to treat non life-threatening illnesses in a chronic setting such as antibiotics or antihistamines. Extrapolating these approaches to drugs for treating cancer over an acute period may not be appropriate. Few specific guidelines are available for risk management of cardiac safety in the development and use of oncology drugs. In this manuscript, clinical and methodological issues related to QTc prolongation assessment will be reviewed. Discussions about limitations in phase-I design and oncology drug development will be highlighted. Efforts are needed to refine strategies for risk management, avoiding unintended consequences that negatively affect patient access and clinical development of promising new cancer treatments. A thoughtful risk management plan generated by an organized collaboration between oncologists, cardiologists, and regulatory agencies to support a development programme essential for oncology agents with cardiac safety concerns.

Molecular determinants of hERG channel block by terfenadine and cisapride

Block of cardiac hERG K+ channels by the antihistamine terfenadine and the prokinetic agent cisapride is associated with prolonged ventricular repolarization and an increased risk of ventricular arrhythmia. Here, we used a site-directed mutagenesis approach to determine the molecular determinants of hERG block by terfenadine and cisapride. Wild-type and mutant hERG channels were heterologously expressed in Xenopus laevis oocytes and characterized by measuring whole cell currents with two-microelectrode voltage clamp techniques. Mutation of T623, S624, Y652, or F656 to Ala reduced channel sensitivity to block by terfenadine. The same mutations reduced sensitivity to cisapride. These data confirm our previous findings that polar residues (T623, S624) located near the base of the pore helix and aromatic residues (Y652, F656) located in the S6 domain are key molecular determinants of the hERG drug binding site. Unlike methanesulfonanilides (dofetilide, MK-499, E-4031, ibutilide) or clofilium, mutation of V625, G648, or V659 did not alter the sensitivity of hERG channels to terfenadine or cisapride. As previously proposed by molecular modeling studies (Farid R, et al. Bioorg Med Chem. 2006;14:3160-3173), our findings suggest that different drugs can adopt distinct modes of binding to the central cavity of hERG.

Fexofenadine hydrochloride in the treatment of allergic disease: a review

Fexofenadine is a selective, non-sedating H1 receptor antagonist, marketed in the United States since 2000. The FDA approved an oral suspension in 2006, for the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria in children. The tablet, capsule, and oral suspension are bioequivalent. Although fexofenadine does not use P450 CYP 3A4 it does interact with a number of drugs at P-glycoprotein and organic anion transporter polypeptides. The risk of toxicity from other drugs may increase with the administration of fexofenadine. Orange and grapefruit juices reduce the bioavailability of fexofenadine. Fexofenadine has been shown to have an impact on inflammatory mediators, other than histamine, such as decreasing the production of LTC₄, LTD₄, LTE₄, PGE₂, and PGF_2α; inhibiting cyclo-oxygenase 2, thromboxane; limiting iNOS generation of NO; decreasing cytokine levels (ICAM-1, ELAM-1, VCAM-1, RANTES, I-TAC, MDC, TARC, MMP-2, MMP-9, tryptase); and diminishing eosinophil adherence, chemotaxis, and opsonization of particles. These effects may provide benefit to some of the inflammatory responses of an acute allergic reaction and provide a basis for future development of H1 antagonists with stronger anti-inflammatory effects. These studies also support the contention that fexofenadine is effective for the treatment of allergic rhinits and chronic idiopathic urticaria.

Allergic rhinitis--current pharmacotherapy

The use of pharmacotherapy for allergic rhinitis remains a central strategy in the integrated treatment of the patient. The most appropriate medical therapy depends upon the nature of specific rhinitis symptoms, patient tolerance to and preference for certain classes of medications, and response to treatment. Through an appreciation of these various physiological mechanisms, the physician can select the treatment option or options that will be most likely to effectively manage symptoms.

Treatment for allergic rhinitis and chronic idiopathic urticaria: focus on oral antihistamines

OBJECTIVE

To review the efficacy and safety of first- and newer-generation antihistamines for the management of allergic rhinitis and chronic idiopathic urticaria (CIU), with a focus on management in the pharmacy.

DATA SOURCES

A literature review was performed using MEDLINE (1966-October 2005), with no time or language restrictions. Key words or phrases used were histamine, antihistamine(s), first- and second-generation, allergic rhinitis, chronic idiopathic urticaria, quality of life, impairment, sedation, cost-effectiveness, astemizole, cetirizine, desloratadine, diphenhydramine, fexofenadine, loratadine, hydroxyzine, ketotifen, and mizolastine. Additional references were found in the bibliographies of the articles cited.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials and other experimental studies of the use of antihistamines for the management of allergic rhinitis and CIU were selected. Review papers and guidelines were also included.

DATA SYNTHESIS

First-generation antihistamines are effective at ameliorating the symptoms of allergic rhinitis and CIU; however, they are associated with adverse effects due to a lack of selectivity for the histamine H(1)-receptor and an ability to bind to cerebral H(1)-receptors. Newer-generation agents, in general, possess high H(1)-receptor selectivity and a low tendency to cross the blood-brain barrier, while maintaining efficacy. In general, safety at elevated doses has been demonstrated for the newer antihistamines, although higher rates of sedation and impairment have been reported with increasing doses for some agents.

CONCLUSIONS

Pharmacists can play an important role in the management of allergic rhinitis and CIU by considering the relative advantages of newer-generation agents when reviewing treatment options.

Evaluation of the optimal oral antihistamine for patients with allergic rhinitis

Because of its bothersome symptoms, allergic rhinitis (AR) is 1 of the top 10 reasons for patient visits to primary care physicians. This highly prevalent disease also results in loss of productivity, both at work and in school. Oral antihistamines are one of the most frequently prescribed medications for the management of AR and, with several agents available, it is important to discern the specific benefits and detriments of each. To assess the differences in efficacy and safety factors among antihistamines, the Individual therapeutic window of each agent can be used as a comparative reference tool because it defines the dose range over which an antihistamine is efficacious and free of adverse effects. As such, the therapeutic window includes both undesired effects, such as sedation, and desired properties, such as rapid onset of action, long duration of efficacy, broad age range of applicability, and potential to Improve quality of life. Therefore, agents with broad therapeutic windows, based on both efficacy and safety, are expected to be more favorable; this therapeutic window should be understood by the primary care physician when prescribing a medication.

Antihistamines in Dermatology

Along with antibiotics, antihistamines are the most widely used systemic drugs in dermatology. This is attributable to the major role played by histamine in common diseases such as urticaria and atopic eczema. Of the currently recognised four subtypes of G protein-coupled histamine receptors, only the H1 and H2 subtypes have been positively identified in human skin. Traditionally believed to be competitive antagonists of histamine, H1 and H2 antihistamines are now considered to behave as inverse agonists. By consensus, H1 antihistamines are classified as 'first generation' (associated with troublesome side-effects including somnolence, anti-adrenergic and atropine-like actions) and 'second-generation' compounds (in which these side-effects are reduced or absent). The main indications for H1 antihistamines in skin are suppression of pruritus in urticaria and atopic eczema, both of which are associated with increased mast cell numbers and tissue histamine levels. However the evidence basis for use in atopic eczema is ambiguous and controversial, even though these drugs are widely used in practice. Currently, significant side-effects are mainly confined to the first-generation compounds and are especially troublesome in the elderly. Psychomotor impairment may persist throughout the day following administration. Anti-cholinergic and anti-alpha-adrenergic blockade and cardiotoxicity (torsade de pointes) may also occur with first-generation antihistamines. Two early low-sedation second-generation antihistamines caused arrhythmias in a small number of patients but these compounds have now been withdrawn. Generally, the second-generation H1 antihistamines are well tolerated.

Pediatric Allergic Rhinitis: Factors Affecting Treatment Choice

Allergic rhinitis is the most prevalent chronic allergic disease in children. Although it is not life-threatening, it can have a significantly detrimental effect on a child's quality of life, and it may exacerbate a number of common comorbidities, including asthma and sinusitis. The Allergic Rhinitis and its Impact on Asthma guidelines, an evidence-based algorithm for the treatment of allergic rhinitis, advocate the use of antihistamines for the treatment of the broad spectrum of the disease. However, first-generation antihistamines are associated with a number of adverse events, including central nervous system impairment and anticholinergic and cardiovascular effects. Moreover, these agents have not been rigorously tested in the pediatric population. Nevertheless, first-generation antihistamines remain the most frequently prescribed agents in this class of drugs. This is despite the fact that the second-generation antihistamines are largely free of the undesirable side effects associated with their predecessors and the fact that they have been shown to be effective in relieving allergic rhinitis symptoms in children in a number of large-scale clinical trials. Therefore, when selecting an antihistamine for a child, it would be prudent to consider the full range of antihistamines and to base the selection of a particular drug on its efficacy, onset and duration of action, and safety profile.

Safety and efficacy of oral fexofenadine in children with seasonal allergic rhinitis--a pooled analysis of three studies

Allergic rhinitis is one of the most common clinical conditions in children; however, data regarding the safety of antihistamines in children with seasonal allergic rhinitis are limiting. To evaluate the safety and efficacy of fexofenadine in children with seasonal allergic rhinitis, data were pooled from three, double-blind, randomized, placebo-controlled, parallel-group, 2-week trials in children (6-11 year) with seasonal allergic rhinitis. All studies assessed fexofenadine HCl 30 mg b.i.d.; two studies included fexofenadine HCl at 15 and 60 mg b.i.d. Patients (and investigators) reported any adverse events during the trial. Physical examinations, including measurements of vital signs and laboratory tests, were performed. Efficacy assessments (total symptom score and individual symptom scores) were evaluated. Exposure to fexofenadine HCl 30 mg b.i.d. and to any fexofenadine dose exceeded 10,000 and 17,000 patient days, respectively. Incidences of adverse events, and discontinuations because of adverse events, were low and similar across treatment groups. In the placebo group, 24.4% of subjects reported adverse events compared with 24.1% for fexofenadine HCl 30 mg b.i.d., and 28.4% for all fexofenadine-treated groups. The most common adverse event overall was headache (4.3% placebo; 5.8% fexofenadine HCl 30 mg b.i.d.; and 7.2% any fexofenadine doses). Treatment-related adverse events were similar across treatment groups with no sedative effects. Fexofenadine HCl 30 mg b.i.d. was significantly superior to placebo in reducing the total symptom score and all individual seasonal allergic rhinitis symptoms, including nasal congestion (p < 0.05). Fexofenadine, at doses of up to 60 mg b.i.d., is safe and non-sedating, and fexofenadine HCl 30 mg b.i.d. effectively reduces all seasonal allergic rhinitis symptoms in children aged 6-11 years.

Safety and Tolerability of Treatments for Allergic Rhinitis in Children

Allergic rhinitis is a common condition in adults and children and can have a large impact on patients' health and quality of life. The aim of current allergic rhinitis therapies is to treat the subjective symptoms and to improve objective measures of the disease. Of the available treatment options for paediatric allergic rhinitis, the newer oral antihistamines and intranasal corticosteroids are first-line treatments.First-generation antihistamines are associated with unwanted adverse effects such as cardiotoxicity, sedation and impairment of psychomotor function. Despite results from studies using first-generation antihistamines demonstrating impairment of cognitive and academic function in children, many of these agents are still commonly given to patients. The newer antihistamines, developed with the aim of being more specific for the histamine H(1) receptor and of overcoming these adverse effects, are the medication of choice in patients with mild intermittent allergic rhinitis. For children <12 years of age, three newer oral antihistamines are currently available: cetirizine, loratadine and fexofenadine. A lack of adverse effects with these antihistamines has been demonstrated in children using EEG and psychomotor performance tests, and in clinical studies. However, issues of receptor selectivity and the potential for CNS adverse effects still remain, and further studies are warranted.Intranasal corticosteroids are the most effective anti-inflammatory agents used for the treatment of paediatric allergic rhinitis; however, the safety of these compounds remains controversial. The safety implications associated with corticosteroids are long-term, dose-related systemic effects, such as suppression of adrenocortical function, growth and bone metabolism, and the extent of these effects is influenced by a number of factors including corticosteroid type, pharmacokinetic profile, mode of delivery and delivery device. Topical corticosteroids were introduced to reduce the systemic effects seen with the long-term use of oral agents. The intranasal corticosteroids currently available for the treatment of paediatric allergic rhinitis - beclometasone, budesonide, flunisolide, fluticasone propionate, mometasone and triamcinolone - have short half-lives and rapid first-pass hepatic metabolism; however, their pharmacokinetics vary in terms of systemic absorption, potency, binding affinity, lipophilicity, volume of distribution, and half-life. A number of studies - utilising hypothalamic-pituitary-adrenal axis function tests such as plasma cortisol levels, 24-hour urinary-free cortisol tests; stimulation tests with corticotropin (adrenocorticotropic hormone), lypressin, and corticotropin-releasing hormone; and growth assessment studies using knemometry and stadiometry - have indicated that these intranasal corticosteroids are well-tolerated in paediatric patients and do not significantly affect growth. The wealth of clinical data and the recommendations from evidence-based guidelines suggest that both antihistamines and intranasal corticosteroids have good safety profiles in children. Nevertheless, growth should be regularly monitored in children receiving intranasal corticosteroids. Other treatments such as immunotherapy, local chromones and decongestants can also be beneficial in managing paediatric allergic rhinitis, and therapies should be considered on an individual basis.

Evaluation of drug-induced QT interval prolongation: implications for drug approval and labelling

Assessment of proarrhythmic toxicity of newly developed drugs attracts significant attention from drug developers and regulatory agencies. Although no guidelines exist for such assessment, the present experience allows several key suggestions to be made and an appropriate technology to be proposed. Several different in vitro and in vitro preclinical models exist that, in many instances, correctly predict the clinical outcome. However, the correspondence between different preclinical models is not absolute. None of the available models has been demonstrated to be more predictive and/or superior to others. Generally, compounds that do not generate any adverse preclinical signal are less likely to lead to cardiac toxicity in humans. Nevertheless, differences in likelihood offer no guarantee compared with entities with a preclinical signal. Thus, the preclinical investigations lead to probabilistic answers with the possibility of both false positive and false negative findings. Clinical assessment of drug-induced QT interval prolongation is crucially dependent on the quality of electrocardiographic data and the appropriateness of electrocardiographic analyses. An integral part of this is a precise heart rate correction of QT interval, which has been shown to require the assessment of QT/RR relationship in each study individual. The numbers of electrocardiograms required for such an assessment are larger than usually obtained in pharmacokinetic studies. Thus, cardiac safety considerations need to be an integral part of early phase I/II studies. Once proarrhythmic safety has been established in phase I/II studies, large phase III studies and postmarketing surveillance can be limited to less strict designs. The incidence of torsade de pointes tachycardia varies from 1 to 5% with clearly proarrhythmic drugs (e.g. quinidine) to 1 in hundreds of thousands with drugs that are still considered unsafe (e.g. terfenadine, cisapride). Thus, not recording any torsade de pointes tachycardia during large phase III studies offers no guarantee, and the clinical premarketing evaluation has to rely on the assessment of QT interval changes. However, since QT interval prolongation is only an indirect surrogate of predisposition to the induction of torsade de pointes tachycardia, any conclusion that a drug is safe should be reserved until postmarketing surveillance data are reviewed. The area of drug-related cardiac proarrhythmic toxicity is fast evolving. The academic perspective includes identification of markers more focused compared with simple QT interval measurement, as well as identification of individuals with an increased risk of torsade de pointes. The regulatory perspective includes careful adaptation of new research findings.

Comparison of the efficacy, safety and quality of life provided by fexofenadine hydrochloride 120 mg, loratadine 10 mg and placebo administered once daily for the treatment of seasonal allergic rhinitis

BACKGROUND

As there have been no previously published studies, this multinational, double-blind, randomized, placebo-controlled, parallel group study compared the efficacy, safety and impact on quality of life (QoL) in seasonal allergic rhinitis patients (SAR) of fexofenadine and loratadine (with placebo), when administered once daily.

METHODS

Six hundred and eighty-eight SAR patients were randomized to receive fexofenadine HCl 120 mg, loratadine 10 mg or placebo, once daily for 2 weeks. The key parameters were the change from baseline in: mean 24-h reflective total symptom scores (TSS); sum of four individual symptom scores, excluding nasal congestion; instantaneous TSS; individual symptom scores including nasal congestion; and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ). Adverse events were recorded.

RESULTS

Mean 24-h reflective and instantaneous TSS were significantly reduced by both fexofenadine HCl (both P </= 0.0001) and loratadine (P </= 0.001 and P </= 0.005, respectively) compared with placebo (n = 639). Among individual symptom scores, fexofenadine HCl was significantly better than loratadine in improving 24-h reflective itchy, watery, red eyes, as well as relieving nasal congestion (P </= 0.05 for both). Fexofenadine HCl was also significantly better than loratadine (P </= 0.03) and placebo (P </= 0.005) in improving QoL, and the differences were of a magnitude considered to be clinically relevant. Loratadine had no statistically significant effect on QoL compared with placebo. The incidence of adverse events was low and similar across all treatment groups.

CONCLUSION

Fexofenadine HCl and loratadine administered once daily are effective and well tolerated in SAR. In this study, fexofenadine HCl was significantly more effective than loratadine in relieving eye symptoms and nasal congestion. Furthermore, fexofenadine was significantly better than loratadine in improving QoL.

Fexofenadine: a review of its use in the management of seasonal allergic rhinitis and chronic idiopathic urticaria

Fexofenadine, the active metabolite of terfenadine, is a selective histamine H1 receptor antagonist that does not cross the blood brain barrier and appears to display some anti-inflammatory properties. Fexofenadine is rapidly absorbed (onset of relief < or = 2 hours) and has a long duration of action, making it suitable for once daily administration. Clinical trials (< or = 2 weeks' duration) have shown fexofenadine 60 mg twice daily and 120 mg once daily to be as effective as loratadine 10 mg once daily, and fexofenadine 120 mg once daily to be as effective as cetirizine 10 mg once daily in the overall reduction of symptoms of seasonal allergic rhinitis. When given in combination, fexofenadine and extended release pseudoephedrine had complementary activity. Fexofenadine was effective in relieving the symptoms of sneezing, rhinorrhoea, itchy nose palate or throat, and itchy, watery, red eyes in patients with seasonal allergic rhinitis. There were often small improvements in nasal congestion that were further improved by pseudoephedrine. Fexofenadine produced greater improvements in quality of life than loratadine to an extent considered to be clinically meaningful, and enhanced patients' quality of life when added to pseudoephedrine treatment. Although no comparative data with other H1 antagonists exist, fexofenadine 180 mg once daily was effective in reducing the symptoms of chronic idiopathic urticaria for up to 6 weeks. Fexofenadine was well tolerated in clinical trials in adults and adolescents and the adverse event profile was similar to placebo in all studies. The most frequently reported adverse event during fexofenadine treatment was headache, which occurred with a similar incidence to that seen in placebo recipients. Fexofenadine does not inhibit cardiac K+ channels and is not associated with prolongation of the corrected QT interval. When given alone or in combination with erythromycin or ketoconazole, it was not associated with any adverse cardiac events in clinical trials. As it does not cross the blood brain barrier, fexofenadine is free of the sedative effects associated with first generation antihistamines, even at dosages of up to 240 mg/day.

CONCLUSIONS

fexofenadine is clinically effective in the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria for which it is a suitable option for first-line therapy. Comparative data suggest that fexofenadine is as effective as loratadine or cetirizine in the treatment of seasonal allergic rhinitis. In those with excessive nasal congestion the combination of fexofenadine plus pseudoephedrine may be useful. In clinical trials fexofenadine is not associated with adverse cardiac or cognitive/psychomotor effects.