Use of second generation H1 antihistamines in special situations

Antihistamine drugs are one of the therapeutic classes most used at world level, at all ages and in multiple situations. Although in general they have a good safety profile, only the more recent drugs (second generation antihistamines) have been studied specifically with regard to the more important safety aspects. Given the variety of antihistamine drugs, they cannot all be considered equivalent in application to various special clinical situations, so that the documented clinical experience must be assessed in each case or, in the absence of such, the particular pharmacological characteristics of each molecule for the purpose of recommendation in these special situations. In general, there are few clinical studies published for groups of patients with kidney or liver failure, with concomitant multiple pathologies (such as cardiac pathology), in extremes of age (paediatrics or geriatrics) and in natural stages such as pregnancy or lactation, but these are normal situations and it is more and more frequent (among the elderly) for antihistamine drugs to be recommended. This review sets out the more relevant details compiled on the use of antihistamines in these special situations.

Antihistamines in drivers, aircrew and occupations of risk

The most commonly occurring allergic diseases can involve a daytime drowsiness associated with the condition itself. The antihistamines used in their treatment can also have central effects and affect certain occupations concerned with risk, road safety and maritime and air navigation. Cognitive tests, experimental studies and epidemiological data recommend avoiding 1st generation antihistamines for people who must drive regularly and/or professions concerned with safety. Although there are no comparative studies on real driving between 1st and 2nd generation antihistamines, in this type of patients there should be a preference for prescribing those with least possible central effect, especially those which are a good substrate for transmembrane transporter pumps such as P-glycoprotein and therefore have a low capacity for crossing the hematoencephalic barrier, thus allowing a broader window for therapy. In this sense, bilastine is a good P-glycoprotein substrate and shows good tolerance at CNS level, in both psychometric trials and real driving test protocols, even at double the dose recommended in the technical file.

H1 antihistamines and benzodiazepines. Pharmacological interactions and their impact on cerebral function

Antihistamines (AH) have been classified into first and second generation according to their pharmacokinetic properties, structural characteristics and adverse effects. The effects on the central nervous system (CNS) are determined basically by their capacity to cross the hematoencephalic barrier and attach to central H1 receptors. Benzodiazepines (BZD) are drugs with effects on the CNS following their union to the specific location of GABA receptors type A. At low doses, the BZD have sedative and anticonvulsive effects, and as the dose increases it leads to sedation, amnesia and finally unconsciousness. Various studies have been made on the possible interaction between the BZD and the AH H1 with special attention to their effect on the CNS. In some cases these were studies to assess the safety of this association and in others, the aim was different: to see if their joint administration gives a better therapeutic result in pathology related with anxiety syndrome or insomnia. In general it can be said that first generation AH interact with the BZD increasing the sedative effects of the latter. However, second generation AH do not increase these sedative effects, which makes them the chosen drugs to treat allergic rhinitis/rhino-conjunctivitis and urticaria in patients also receiving BZD.

Validation of the modified allergic rhinitis and its impact on asthma (ARIA) severity classification in allergic rhinitis children: the PEDRIAL study

BACKGROUND

A modified allergic rhinitis and its impact on asthma (ARIA) (m-ARIA) criterion to classify the severity of allergic rhinitis (AR) has recently been validated in both treated and untreated adult patients; however, such information in children is lacking. The aim of this study was to validate this m-ARIA severity criterion, which allows for discrimination between moderate and severe AR, in a large pediatric patient sample population.

METHODS

The m-ARIA classification categorizes AR severity into mild (no affected items), moderate (1-3 affected items), and severe (all four affected items). We applied this modified criterion to untreated AR pediatric patients aged 6-12 years, through an observational, cross-sectional, and multicenter study. AR symptoms were assessed using the Total Four Symptom Score (T4SS), and the severity was evaluated by both ARIA severity items and visual analogue scale (VAS).

RESULTS

Allergic rhinitis pediatric patients (N = 1269) from 271 centers were included. Among them, 59.5% had intermittent and 40.5% persistent disease; 89.9% had moderate/severe AR using the original ARIA (o-ARIA) classification and 59.5% had moderate, while 30.5% had severe AR using the m-ARIA criterion. Using the m-ARIA, significantly higher T4SS and VAS scores were obtained when comparing severe with moderate AR.

CONCLUSIONS

The m-ARIA severity classification is a useful clinical tool to discriminate moderate from severe AR among untreated pediatric patients.

Effect of antihistamine up-dosing in chronic urticaria

Chronic urticaria has an important impact upon patient quality of life, and no treatment has yet been developed capable of effectively controlling the disease. The most recent guidelines recommend the use of non-sedating antihistamines at high doses as second-step therapy before resorting to other treatments. The present review examines the studies published to date on the use of H1 antihistamines at doses higher than those indicated as therapeutic doses in chronic urticaria. Most of the studies report no significant differences among the studied doses-only a tendency towards increased response on elevating the dose. There are no clinically well designed, randomized double-blind trials comparing efficacy between therapeutic doses and doses higher than those indicated in the corresponding Summary of Product Characteristics. Likewise, there are insufficient data to conduct a meta-analysis and thus classify the degree of evidence of the few available studies, which moreover present contradictory results. At present, the prescription of high-dose H1 antihistamines is based only on experts opinion. However, considering the high safety profile of these drugs, it would be a good option to evaluate their efficacy at high doses, before moving on to other therapeutic steps.

Effect of bilastine upon the ocular symptoms of allergic rhinoconjunctivitis

Ocular symptoms often accompany allergic rhinitis and can be as or even more bothersome for the patient than the actual nasal symptoms. Ocular manifestations of allergic rhinoconjunctivitis may result from both direct allergen-mediated mast cell stimulation on the surface of the eye and naso-ocular reflexes--histamine being one of the mediators of symptoms onset. An H1 antihistamine would be the first line treatment for allergic conjunctivitis. Since allergic conjunctivitis is always (or almost always) accompanied by nasal symptoms, a second-generation H1 antihistamine administered via oral route is the drug of choice for jointly managing both the nasal and the ocular symptoms--minimizing the impact of the effects inherent to first-generation H, antihistamine, including particularly drowsiness. Bilastine is a new H1 antihistamine with an excellent safety profile, developed for the treatment of allergic rhinoconjunctivitis and urticaria, with potency similar to that of cetirizine and desloratadine, and superior to that of fexofenadine. This new drug has been shown to be effective in controlling the ocular symptoms of allergic rhinoconjunctivitis.

Allergen-specific nasal provocation testing: review by the rhinoconjunctivitis committee of the Spanish Society of Allergy and Clinical Immunology

Specific nasal provocation testing (NPT) consists of eliciting a response from the nasal mucosa by controlled exposure to allergens. It is indicated in the diagnostic confirmation of allergic rhinitis and when discrepancies arise or difficulties exist in the assessment of a patient's medical history and the results of skin and/or serological tests. The technique is also applied to evaluate sensitivity to the allergen, the efficacy and safety profile of treatment, and in research on the pathophysiological mechanisms of nasal response to allergens. NPT also provides information on the etiology of occupational respiratory diseases of allergic origin. Although there have been many studies and publications on the use and standardization of bronchial provocation tests with allergen, few analyze specific NPT. In this review, the Rhinoconjunctivitis Committee of the Spanish Society of Allergy and Clinical Immunology discuss the methodology, monitoring, and assessment of allergen-specific NPT in order to provide a practical and up-to-date review of the technique.

Bilastine and the central nervous system

Antihistamines have been classifed as first or second generation drugs, according to their pharmacokinetic properties, chemical structure and adverse effects. The adverse effects of antihistamines upon the central nervous system (CNS) depend upon their capacity to cross the blood-brain barrier (BBB) and bind to the central H1 receptors (RH1). This in turn depends on the lipophilicity of the drug molecule, its molecular weight (MW), and affinity for P-glycoprotein (P-gp) (CNS xenobiotic substances extractor protein). First generation antihistamines show scant affinity for P-gp, unlike the second generation molecules which are regarded as P-gp substrates. Histamine in the brain is implicated in many functions (waking-sleep cycle, attention, memory and learning, and the regulation of appetite), with numerous and complex interactions with different types of receptors in different brain areas. Bilastine is a new H1 antihistamine that proves to be effective in treating allergic rhinoconjunctivitis (seasonal and perennial) and urticaria. The imaging studies made, as well as the objective psychomotor tests and subjective assessment of drowsiness, indicate the absence of bilastine action upon the CNS. This fact, and the lack of interaction with benzodiazepines and alcohol, define bilastine as a clinically promising drug with a good safety profile as regards adverse effects upon the CNS.

Effect of bilastine upon nasal obstruction

H1 antihistamines constitute one of the main references for the treatment of allergic rhinitis. Classically, these drugs have been considered effective in controlling sneezing, rhinorrhea and itching, though they have not been regarded as particularly effective in application to nasal obstruction. The most recent studies, involving second-generation H1 antihistamines (desloratadine, fexofenadine, levocetirizine, rupatadine), have shown these drugs to offer effects upon nasal obstruction significantly superior to those of placebo. The present review examines the effect of bilastine, a new, potent and highly specific H1 antihistamine without sedative effects or cardiac toxicity, upon nasal obstruction. The analysis of the data from the different clinical trials indicates that in patients with allergic rhinitis, the effect of bilastine upon nasal obstruction is superior to that of placebo and similar to that of other second-generation H1 antihistamines, manifesting within 24 hours after the start of treatment.

Placebo effect in clinical trials involving patients with allergic rhinitis

Interest in understanding the underlying mechanisms of the placebo effect has considerably grown during the last few decades. Studies made in this sense have led to a change in the conception of this peculiar phenomenon, and nowadays the placebo effect is viewed as a psychobiological event resulting from the interaction between individual patient factors and factors relating to the physician and the therapeutic environment. Investigation of the placebo effect in disease conditions such as pain or Parkinson's disease has improved our understanding of its underlying psychological and neurobiological mechanisms. Clinical studies directly designed to investigate the placebo effect have shown placebo to have a more beneficial effect upon diseases evaluated by means of physical or subjective parameters than by means of biochemical parameters. A strong placebo effect has been observed in allergic diseases, where the evaluating parameters tend to be physical or subjective. Biomedical research and the development of new drugs implies an important investment of human and economical resources for conducting clinical trials designed to evaluate the efficacy and safety of new medications. Knowledge of the mechanisms of the placebo effect and how the latter can influence the results of the different efficacy variables in these research studies appears essential in order to optimize the available resources in application to the development of new drugs.

Bilastine and quality of life

The evaluation of quality of life (QoL) and its modification through therapeutic interventions has become a prioritary concern in recent years and a requirement on the part of regulatory agencies for the authorization of new drugs. In clinical studies of allergic disorders, particularly allergic rhinitis and urticaria, different types of generic questionnaires have been used - especially disease specific instruments such as the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) or skin disease specific tools such as the Dermatology Life Quality Index (DLQI). Throughout its clinical development, bilastine has been shown to be more effective than placebo and at least as effective as cetirizine, levocetirizine, fexofenadine or desloratadine in controlling the symptoms of seasonal allergic rhinitis and chronic urticaria. QoL has been studied as a secondary objective in three allergic rhinitis clinical trials, using the RQLQ, in a total of 2335 patients. Likewise, in chronic urticaria, QoL has been evaluated using the DLQI in a total of 525 patients, versus levocetirizine and placebo. The improvement in the QoL parameters in these studies (RQLQ or DLQI domains) at all times proved proportional to the symptoms improvement. In general, the data obtained relating to changes in QoL are concordant with the mean global visual analog scale (VAS in mm) values and their changes, from the beginning until the end of the treatment period, for all of the trials, for bilastine and all its comparators.

Rhinitis and its association with asthma in patients under 14 years of age treated in allergy departments in Spain

BACKGROUND

Allergic rhinitis is the most frequent chronic allergic disease in children, and may be an important risk factor for the subsequent development of asthma.

OBJECTIVE

To describe the characteristics of patients younger than 14 years of age presenting with rhinitis and the possible association with asthma.

METHODS

We carried out a prospective, observational, descriptive, cross-sectional epidemiologic study (Alergológica 2005) of 917 patients under the age of 14 consulting for the first time in allergy departments in Spain.

RESULTS

Rhinitis was diagnosed in 42.5% of the children. The association between asthma and rhinitis was significantly higher in children than in adults (44.9% vs 35.5%; P<.05). Time from onset of rhinitis was significantly associated with the development of asthma (2.97 vs 2.06 years; P<.0001). Allergy was the most frequent cause of rhinitis in children with and without asthma. Allergy to epithelia and fungi was more frequent in children with rhinitis and asthma than in children with rhinitis alone. We found no differences in the frequency of treatment with immunotherapy between children with and without asthma.

CONCLUSION

Rhinitis was frequently associated with asthma in children consulting for the first time at allergy departments. Time since onset of rhinitis and sensitivity to epithelia and fungi were associated with the development of asthma.

Antigens of the major histocompatibility system in ischemic heart disease and idiopathic dilated cardiomyopathy

BACKGROUND

Although dilated cardiomyopathy (DCM) is a disease of unknown and probably multifactorial etiology, a change in immune mechanisms is presumably significant, with many abnormalities in humoral and cellular responses having been reported. The heart thus becomes the target organ for an initial episode of myocardial damage that triggers an autoimmune response.

HYPOTHESIS

The purpose of this study was to analyze the frequency of different human leukocyte antigens in patients with a diagnosis of well-advanced DCM and ischemic heart failure, comparing them with a control group of presumably healthy subjects.

METHODS

The group with dilated cardiomyopathy consisted of 50 patients (7 women and 43 men), aged from 14 to 64 years. The group with ischemic heart disease included 76 patients (4 women and 72 men), with ages ranging from 34 to 64. The control group, consisting of 1,337 presumably healthy subjects from the Spanish Mediterranean area, was recruited based on paternity studies.

RESULTS

Compared with the control group, we found in DCM a greater incidence of B15 (20 vs. 6%) and DQ3 (83 vs. 50%) antigens. In ischemic heart disease we found a lower incidence of A1 (3 vs. 22%), B8 (5 vs. 12%), and DQ2 (16 vs. 50%) in comparison with the control group.

CONCLUSIONS

In the Spanish Mediterranean area, the presence of antigens B-15 and DQ3 would be associated with advanced DCM. The absence of antigens A1, B8, and DQ2 would be associated with the occurrence of severe ischemic heart disease.

Epidemiology of allergic rhinitis in allergy consultations in Spain: Alergológica-2005

BACKGROUND

Allergic rhinitis (AR) is considered to be the most frequent allergic disorder.

OBJECTIVE

To present the data from the Alergológica-2005 on the characteristics of patients with AR.

METHODS

An observational, descriptive, cross-sectional epidemiologic study was performed on 4991 patients consulting for the first time in Allergology services in Spain.

RESULTS

Fifty-five percent of patients consulting Allergology services for the first time were diagnosed with AR, of whom 65% also had conjunctivitis and 37% asthma. Two out of every three subjects with AR consulted their primary care physician twice in the previous 4 months. One third was treated by another specialist in the preceding year and one of every five required treatment in emergency departments. AR affected the quality of life (SF-12), in some cases causing time off work and school. The most frequently involved allergens were pollens (51%), followed by dust mites (42%). Polysensitization was found in 31% of cases. Antihistamines and nasal topical corticoids were the most widely used drugs. In 38% of patients, treatment with specific immunotherapy was begun.

CONCLUSIONS

AR was the leading cause of consultations in Alergológica-2005. Rhinitis was frequently associated with other allergic disorders in 65% of patients with conjunctivitis and 37% with asthma. The illness led to a substantial use of healthcare resources and significantly affected the quality of life of the sufferers.

From pollinosis to digestive allergy

Pollinosis is defined as the appearance of respiratory symptoms (rhinoconjunctivitis and/or asthma) as a result of the inhalation of pollen to which the individual is sensitized. Pollen allergy becomes all the more relevant on taking into account that it may be responsible for the development of plant food allergy, or may even constitute the direct cause of esophageal, gastric and/or intestinal inflammation in the context of a digestive allergic process. Pollen can act as a source of allergens that induce primary sensitization in the host as a result of inhalation, with secondary allergy to plant foods containing shared allergens via a cross-reactivity mechanism. The observed pattern of plant food allergy depends on the dietary habits of the population in a given geographical setting, and on the pollination found in that setting. Pollinosis may account for the greater or lesser prevalence of allergy to certain plant foods, and for the severity of the associated reactions. Beyond the digestive tract inflammation that may result from allergy to a given food, pollinosis is also intrinsically able to generate a clinically relevant or irrelevant Th2-mediated inflammatory response at digestive level, and may even give rise to eosinophilic esophagitis. Inter-relation with the airway may also extend to the digestive tract as a consequence of the systemic response that characterizes allergic disease.

Allergic rhinitis and school performance

Allergic rhinitis is presently the most common chronic disorder in the pediatric population. It can affect sleep at night and cause daytime sleepiness, with school absenteeism, "presenteeism" or inattention, mood disturbances and psychosocial problems. All this in turn can contribute to reduce school performance. The correct treatment of allergic rhinitis can improve school performance, though the first generation antihistamines have unacceptable central and anticholinergic effects that can actually worsen the situation. The second generation antihistamines constitute the drug treatment of choice for allergic rhinitis in children. Vasoconstrictors should not be used in pediatric patients, due to their unpredictable pharmacokinetics and very narrow therapeutic margin. Intranasal corticoids could improve school performance in some patients, by reducing nose block or congestion, the nocturnal sleep disturbances, and daytime sleepiness. Concrete studies of the impact of chromones, anticholinergic agents, antileukotrienes and immunotherapy upon school performance are lacking.

Genetic aspects of allergic rhinitis

The development of allergic rhinitis entails a complex interaction between genetic predisposition and environmental exposure to different factors, of which the most important is the implicated allergen. There is a clear hereditary component in allergic rhinitis that has been well corroborated by segregation studies and investigations in twins. From the strictly genetic perspective, it is believed that the disease may be the result of the interaction of different genetic alterations, each of which would contribute a small defect. In recent years, considerable attention has focused on the genes that may be implicated in allergic rhinitis. A number of genomic searches have been made, yielding different chromosomal associations--the most repeated being those involving chromosomes 2, 3, 4 and 9. Single-nucleotide polymorphism studies involving genes encoding for molecules implicated in the pathogenesis of allergic rhinitis have also been made. Such molecules comprise chemokines and their receptors, interleukins and their receptors, eosinophil peroxidase and leukotrienes, among others.

Molecular diagnosis in allergology: application of the microarray technique

Recombinant and purified allergens are currently available for determining specific IgE targeted to different allergenic components. In this way it is possible to diagnose the sensitization profile of each individual patient. The microarray technique makes it possible to determine specific IgE against multiple allergens simultaneously in one same patient, with a minimum amount of serum, and even allows the determination of IgG and IgM against the same allergens in one same serum sample. Microarray procedures are being developed not only for the determination of antibodies but also for cell activation tests. In addition, microarray technology will help explain cross-reactions, and will facilitate the evaluation of subjects in which skin tests cannot be performed. These techniques will allow a great step forward in the development of immunotherapy specifically targeted to the sensitizations found in each individual patient, yielding especially hypoallergenic forms of great immunogenic capacity, and thus improving the safety and efficacy of immunotherapy. Lastly, microarrays will improve our understanding of the physiopathology of allergic diseases.

Stress and allergy

In recent years it has been seen that the nervous and immune systems regulate each other reciprocally, thus giving rise to a new field of study known as psychoneuroimmunology. Stress is defined as a general body response to initially threatening external or internal demands, involving the mobilization of physiological and psychological resources to deal with them. In other words, stress is characterized by an imbalance between body demands and the capacity of the body to cope with them. The persistence of such a situation gives rise to chronic stress, which is the subject of the present study, considering its repercussions upon different organs and systems, with special emphasis on the immune system and--within the latter--upon the implications in relation to allergic disease. Activation of the neuroendocrine and sympathetic systems through catecholamine and cortisol secretion exerts an influence upon the immune system, modifying the balance between Th1/Th2 response in favor of Th2 action. It is not possible to affirm that chronic stress is intrinsically able to cause allergy, though the evidence of different studies suggests than in genetically susceptible individuals, such stress may favor the appearance of allergic disease on one hand, and complicate the control of existing allergy on the other.

Allergic conjunctivitis and H1 antihistamines

Allergic conjunctivitis is the most common form of ophthalmological allergy. Eye symptoms are one of the main and most frequent reasons for consultation among patients with allergic rhinoconjunctivitis, which in turn is the most common reason for visiting the allergologist, according to the Alergológica 2005 study. Itching is the key symptom of allergic conjunctivitis, and its relief is the principal objective of the broad range of treatment options available. Topical antihistamines with multiple actions (mast cell stabilization, and antiinflammatory and antihistaminic actions) are probably the best treatment option, thanks to their rapid action, safety and convenience of use. However, oral antihistamines (preferentially second generation drugs) can also play an important role, since they are of established efficacy and offer adequate treatment of the nasal symptoms that tend to accompany the ocular manifestations of allergic rhinoconjunctivitis. Models of allergic conjunctivitis are useful for investigational purposes and for advancing our knowledge of allergic reactions. Advances in the study of the physiopathology of ocular allergy allow us to introduce new therapeutic options for the management of such allergic reactions, thanks to the findings derived from models of this kind. The present review provides an update to the published data on allergic conjunctivitis and the current role of both topical and ocular antihistamines in treating the disorder.

Chronic urticaria: do urticaria nonexperts implement treatment guidelines? A survey of adherence to published guidelines by nonexperts

BACKGROUND

Guidelines including level of evidence and grade of recommendation were recently published for chronic urticaria (CU).

OBJECTIVES

To describe the therapeutic approach in patients with CU, and to depict how recent guidelines are implemented in the daily practice of management of CU.

METHODS

We performed a cross-sectional multicentre study through a questionnaire answered by 139 specialists. In total, 695 patients were evaluated, mean+/-SD age 42.3+/-15 years, 62.1% women. Of the patients, 168 were treated by an allergist, 473 by a dermatologist and in 54 cases the specialist was not stated. The drug prescribed was the main variable, and chi2 and Fisher's tests were utilized for the statistical analysis.

RESULTS

Nonsedating anti-H1 antihistamines taken regularly were the most common drugs prescribed, followed by nonsedating anti-H1 antihistamines taken as needed, corticosteroids, sedating antihistamines taken regularly, sedating antihistamines taken as needed, anti-H2 antihistamines, leukotriene antagonists, ciclosporin and doxepin. Nonsedating antihistamines plus corticosteroids was the most frequent drug combination prescribed. When comparing between allergists and dermatologists we found a positive and significant correlation only between prescription of cetirizine, dexchlorfeniramine, leukotriene antagonists and anti-H2 antihistamines and being treated by an allergist. A positive correlation was found with desloratadine and being seen by a dermatologist. We did not find any difference in CU management in the rest of the treatments studied.

CONCLUSIONS

It is surprising that a large amount of sedating antihistamines was prescribed. In many instances these were prescribed as needed. This fact could have a negative impact on urticaria control and patient satisfaction. It seems difficult for the nonexpert to differentiate between CU and any kind of physical urticaria.