Antihistamines in late-phase clinical development for allergic disease

Antiallergic Effects of Phenolic Compounds Isolated From Stellera chamaejasme on RBL-2H3 Cells

The current study was undertaken to isolate and identify anti-inflammatory and antiallergic active compounds in the ethyl acetate and butanol fractions of an ethanolic extract of the aerial parts of Stellera chamaejasme (SCAE). A new maltol glucoside, maltol 3-(6″-(2-( E)-butenoyl)-glucoside) and benzoic acid, daphnoretin (a coumarin), 6 flavonoids (apigenin, genkwanin, taxifolin, apigenin 7- O-glucoside, luteolin 7- O-sambubioside, genkwanin 5- O-glucoside), and 2 lignans (matairesinoside and lariciresinol) were isolated from SCAE by chromatographic separation. Their chemical structures were elucidated by analyzing spectroscopic data, including 1-dimensional and 2-dimensional nuclear magnetic resonance (Fig1). Maltol 3-(6″-(2-( E)-butenoyl)-glucoside) significantly inhibited β-hexosaminidase release by 85.5% in immunoglobulin E and dinitrophenyl/bovine serum albumin (DNP/BSA)-induced RBL-2H3 cells. Benzoic acid from S. chamaejasme inhibited β-hexosaminidase release (by 80.2%) in IgE and DNP/BSA-induced RBL-2H3 cells and interleukin-4 messenger ribonucleic acid expression (by 21.9% inhibition) in propidium iodide-induced RBL-2H3 cells.

Comparison of Efficacy, Safety and Cost-effectiveness of Rupatadine and Olopatadine in Patients of Chronic Spontaneous Urticaria: A Randomized, Double-blind, Comparative, Parallel Group Trial

Objective:

To compare efficacy, safety and cost-effectiveness of rupatadine and olopatadine in patients of chronic spontaneous urticaria.

Materials and Methods:

A 6-week, single-centered, randomized, double blind, parallel group comparative clinical study was conducted on patients with chronic spontaneous urticaria. Following inclusion and exclusion criteria, 60 patients were recruited and were randomized to two treatment groups and received the respective drugs for 6 weeks. At follow-up, parameters assessed were mean total symptom score (MTSS) calculated by adding the mean number of wheals (MNW) and the mean pruritus score (MPS), number of wheals, size of wheal, scale for interference of wheals with sleep (SIWS).

Results:

Both the drugs significantly reduced the MTSS, number of wheals, size of wheal, scale for interference of wheals with sleep, but olopatadine was found to be superior. In olopatadine group, there was significantly higher reduction in MTSS (p = 0.01), Number of wheals (P < 0.05), Size of wheals (p < 0.05), Scale for intensity of erythema (p < 0.05) and change in eosinopils count (p = 0.015) than that of rupatadine. Incidence of adverse effects was found to be less in olopatadine group when compared with rupatadine group. Cost effectiveness ratio was less in olopatadine group as compared to rupatadine group throughout the treatment.

Conclusions:

Olopatadine is a better choice in chronic spontaneous urticaria in comparison to rupatadine due to its better efficacy, safety and cost effectiveness profile.

International Union of Basic and Clinical Pharmacology. XCVIII. Histamine Receptors

Histamine is a developmentally highly conserved autacoid found in most vertebrate tissues. Its physiological functions are mediated by four 7-transmembrane G protein-coupled receptors (H1R, H2R, H3R, H4R) that are all targets of pharmacological intervention. The receptors display molecular heterogeneity and constitutive activity. H1R antagonists are long known antiallergic and sedating drugs, whereas the H2R was identified in the 1970s and led to the development of H2R-antagonists that revolutionized stomach ulcer treatment. The crystal structure of ligand-bound H1R has rendered it possible to design new ligands with novel properties. The H3R is an autoreceptor and heteroreceptor providing negative feedback on histaminergic and inhibition on other neurons. A block of these actions promotes waking. The H4R occurs on immuncompetent cells and the development of anti-inflammatory drugs is anticipated.

Desloratadine citrate disodium injection, a potent histamine H(1) receptor antagonist, inhibits chemokine production in ovalbumin-induced allergic rhinitis guinea pig model and histamine-induced human nasal epithelial cells via inhibiting the ERK1/2 and NF-kappa B signal cascades

Chemokines have chemotactic properties on leukocyte subsets whose modulation plays a pivotal role in allergic inflammatory processes. Our present study was designed to investigate the anti-allergic and anti-inflammatory properties of desloratadine citrate disodium injection (DLC) and elucidate the molecular mechanisms of its anti-inflammatory properties. The anti-allergic effects of DLC were evaluated based on allergic symptoms, serological marker production and histological changes of the nasal mucosa in guinea pigs model of allergic rhinitis. The anti-inflammatory properties and molecular mechanisms of DLC were explored by studying the regulation of a set of chemokines and extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) pathways, after DLC treatment in guinea pigs model of allergic rhinitis in vivo and histamine-activated human nasal epithelial cells (HNECs) in vitro. In vivo model in guinea pigs, DLC alleviated the rhinitis symptoms, inhibited inflammatory cells infiltration in nasal lavage fluid (NLF) and histamine, monocyte chemotactic protein (MCP)-1, regulated on activation normal T cell expressed, and presumably secreted (RANTEs) and interleukin (IL)-8 release in sera and P-ERK1/2 and NF-κB activation in nasal mucosa. In vitro, DLC markedly inhibited histamine-induced production of MCP-1, RANTEs and IL-8 and suppressed c-Raf, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) and ERK1/2 activation in HNECs. These results provide evidence that DLC possesses potent anti-allergic and anti-inflammatory properties. The mechanism of action underlying DLC in allergic inflammation appears to be inhibition of the phosphorylation of ERK1/2, in addition to blocking of the NF-κB pathway.

Anti-allergic and anti-inflammatory properties of a potent histamine H1 receptor antagonist, desloratadine citrate disodium injection, and its anti-inflammatory mechanism on EA.hy926 endothelial cells

The present study, demonstrates that, desloratadine citrate disodium injection (DLC) possesses antihistaminic, anti-allergic and anti-inflammatory properties and elucidates its molecular mechanisms of anti-inflammatory properties. In vitro antihistamine activity of DLC was determined in guinea pig isolated tissues. In vivo antihistamine effects were evaluated after following intravenous administration of DLC in mice with histamine- induced paw edema and in rats with increased capillary permeability. Anti-allergic effects were assessed through passive cutaneous anaphylactic (PCA) reactions in sensitized rodents and ovalbumin-induced allergic rhinitis in rats. Anti-inflammatory properties and molecular mechanisms of DLC were determined on histamine- and lipopolysaccharide (LPS)-induced EA.hy926 endothelial cells. DLC exhibited significant and reversible inhibition of histamine-induced contractions of isolated guinea pig ileum with pA2 value of 8.88. Histamine-induced paw edema and increased capillary permeability were notably inhibited by DLC intravenous administration. In the model of PCA reactions, DLC showed significant activity in a dose-dependent nd potently inhibited both the early-phase and late-phase allergic reaction of ovalbumin-induced allergic rhinitis in rats. DLC alleviated the rhinitis symptoms and inhibited inflammatory cell infiltration, IL-4 and protein leakage in nasal lavage fluid (NLF). In EA.hy926 cells, DLC significantly inhibited the histamine- and LPS- induced IL-6 and IL-8 production and P-selectin and intercellular cell adhesion molecule-1 (ICAM-1) expression. Moreover, DLC reduced translocation of nuclear factor-kappaB (NF-κB) to the nucleus in activated EA.hy926 cells. These results provide evidence that DLC possesses potent antihistaminic, anti-allergic and, anti-inflammatory properties via suppressing IL-6, IL-8, P-selectin and ICAM-1 expression.

Rupatadine for the treatment of urticaria

INTRODUCTION

Rupatadine fumarate is a second-generation antihistamine provided with a potent, long-lasting and balanced in vivo dual platelet-activating factor (PAF) and histamine antagonist activity and it uniquely combines both activities at a high level of potency. Rupatadine has a rapid onset of action and a long-lasting effect, so a once-daily dosing is permitted, moreover is well tolerated by young adults and the elders. Rupatadine does not present the side effects of first-generation H1-antihistamines, such as somnolence, fatigue, headache, impaired memory and learning, sedation, increased appetite, dry mouth, dry eyes, visual disturbances, constipation, urinary retention and erectile dysfunction.

AREAS COVERED

This study evaluates the effectiveness and safety of rupatadine in chronic urticaria (CU) and acquired cold urticaria (ACU), through a systematic review of the literature.

EXPERT OPINION

Patients affected by urticaria are often discouraged because frequently their disease does not recognize a cause and it is unresponsive to treatments. Patients can control their symptoms assuming second-generation H1-antihistamines, such as rupatadine. Several randomized, double-blind, placebo-controlled trials testify effectiveness and safety of rupatadine in CU and ACU. However, further clinical trials to evaluate the efficacy of rupatadine in different urticaria subtypes and to test the safety of doses higher than 20 mg are encouraged.

Safety evaluation of desloratadine in allergic rhinitis

INTRODUCTION

Desloratadine is a biologically active metabolite of second-generation antihistamine loratadine. It is also indicated for the treatment of allergic diseases, including allergic rhinitis.

AREAS COVERED

A Medline search was conducted to identify preclinical and clinical studies of desloratadine. This was supplemented with additional articles obtained from online sources. The focus of this review is on the safety profile of desloratadine.

EXPERT OPINION

The review of these data indicates that the safety profile of desloratadine is similar to other second-generation antihistamines. Desloratadine is highly selective for histamine H₁-receptors, does not cross the blood-brain barrier (BBB), and has minimal adverse events (very low sedation rate), with a better safety and tolerability than first-generation antihistamines. Desloratadine is safe and well tolerated without having central nervous system (CNS) or cardiovascular effects and with low drug interaction.

Assessment of the efficacy of antihistamine drugs in complex treatment of chronic itchingdermatoses

The authors give a review of current concepts of mechanisms of skin itching development for different types of chronic dermatoses. The authors also present the results of a study aimed at assessing the efficacy of different 2nd generation antihistamine drugs used for complex treatment of 83 patients aged 14-73 suffering from different chronic itching dermatoses (atopic dermatitis, eczema, pruritus, chronic urticaria, progressing psoriasis, lichen acuminatus, contact allergic dermatitis). The authors conclude that Glencet (levocetirizine) used in a complex therapy of dermatoses accompanied with itching can efficiently arrest both subjective itching sensations and objective clinical symptoms of the diseases as well as reliably (р < 0.001) reduce the term of inpatient care by 4.8 ± 2.3 on average. Glencet (levocetirizine) is a drug of choice among the 2nd generation antihistamine drugs used for treatment of chronic skin diseases accompanied with itching.

Early activation of mucosal mast cells during the primary immune response in a rodent model of neonatal asthma

During an allergic inflammatory response in the airway, if a failure of the epithelial cell barrier occurs before the systemic immune response is triggered by allergens, more allergens can invade. Using a rat model of asthma, we previously found that mucosal mast cells, which localise to the epithelial layer of the airways, are activated to promote a pro-asthmatic immune response. In this study, we developed a neonatal rat model of allergic airway hypersensitivity that mimics some features of childhood asthma. Airway hypersensitivity was measured using unrestrained whole-body plethysmography after analysis of the serum IgE titre. Inflammatory cells and inflammatory mediators in bronchoalveolar lavage fluid samples were examined. Two mast cell-specific proteases were detected using PCR. In addition, we analysed the phenotype and the number of mast cells in the airways by immunohistochemistry, and we found that the number of mucosal mast cells and the expression level of the proteases increased 2 weeks after sensitisation. Changes in the IgE titre, airway hypersensitivity and the activation of other inflammatory cells were delayed, appearing during the 4 weeks after sensitisation. Our results indicate that the activation of mucosal mast cells contributes to the pro-asthmatic immune response. This activation may be a biomarker allowing early intervention that could help prevent allergic airway inflammation.

Safety and efficacy of desloratadine in subjects with seasonal allergic rhinitis or chronic urticaria: results of four postmarketing surveillance studies

BACKGROUND AND OBJECTIVE

Allergic rhinitis (AR) and chronic urticaria (CU) are common diseases with symptoms that impair quality of life. Second-generation antihistamines (e.g. cetirizine, desloratadine, fexofenadine, loratadine and mizolastine) are recommended first-line treatment for both conditions; however, studies of clinically relevant differences among these agents are lacking. The aim of this investigation was to evaluate the safety, tolerability and efficacy of desloratadine 5 mg once daily in four postmarketing surveillance studies in subjects with seasonal AR (SAR) or chronic idiopathic urticaria (CIU) in real-world clinical practice settings.

METHODS

This programme of prospective surveillance studies was conducted in Germany between February 2001 and March 2002 in allergy; dermatology; ear, nose and throat; or general practice settings. Subjects (total number 77 880) were aged > or =12 years and met the requirements for treatment of SAR or CIU with desloratadine as outlined in the package insert. All subjects received oral desloratadine 5 mg once daily for a mean duration of up to 40.4 days. Adverse events (AEs) were reported throughout the studies; serious AEs were recorded for up to 30 days after treatment. Investigators and subjects both rated tolerability at the end of treatment. Symptom severity and sleep and daily activity impairment were evaluated at baseline and after treatment using 4-point scales (0 = none; 1 = mild; 2 = moderate; 3 = severe). A post hoc subanalysis assessed desloratadine efficacy and onset of symptom relief in subjects who had received monotherapy with another second-generation antihistamine.

RESULTS

A total of 386 AEs were reported by 287 subjects (0.37%) in the four studies. The most commonly reported treatment-related AEs were fatigue (0.07%), headache (0.07%), dry mouth (0.04%) and nausea (0.03%). Tolerability was rated as excellent/good by 99.1% of investigators and 98.5% of subjects. Desloratadine therapy significantly reduced nasal and ocular symptom severity, itching and wheals, and sleep and activity disruption (p < 0.0001), as indicated by a reduction in mean total and individual symptom scores, and reported impairment of sleep and daily activities. The efficacy of desloratadine was rated as significantly greater by 59.4-88.0% of subjects who had previously received monotherapy with cetirizine, fexofenadine, loratadine or mizolastine (p < 0.01 for all). The percentage of subjects who rated onset of symptom relief with desloratadine as faster than previous treatment ranged from 51.6% to 82.4%.

CONCLUSION

Desloratadine was safe, well tolerated and efficacious in this series of surveillance studies. A post hoc analysis of subjects who had received previous monotherapy with a second-generation antihistamine found that most subjects rated efficacy as higher than their previous treatment, with a faster onset of symptom relief.

Minimal persistent inflammation in allergic rhinitis: implications for current treatment strategies

Patients with allergic rhinitis have traditionally been placed into 'seasonal' and 'perennial' categories, which do not account for the subclinical inflammatory state that exists in many patients. In subjects with seasonal and perennial allergic rhinitis, even subthreshold doses of allergen have been found to cause inflammatory cell infiltration in the nasal mucosa, including increases in expression of cellular adhesion molecules, nasal and conjunctival eosinophilia, and other markers of inflammation, which do not result in overt allergy symptoms. This state - which has been termed 'minimal persistent inflammation'- may contribute to hyperreactivity and increased susceptibility to development of clinical symptoms as well as common co-morbidities of allergic rhinitis, such as asthma. Treating overt allergy symptoms as well as this underlying inflammatory state requires agents that have well-established clinical efficacy, convenient administration, potent anti-inflammatory effects and proven long-term safety, so that long-term continuous administration is feasible. Of the three major classes of commonly used allergic rhinitis medications - intranasal corticosteroids, anti-histamines, and anti-leukotrienes - intranasal corticosteroids appear to represent the most reasonable therapeutic option in patients who would benefit from continuous inhibition of persistent inflammation.

FUTURA STUDY-Evaluation of efficacy and safety of rupatadine fumarate in the treatment of persistent allergic rhinitis

Allergic rhinitis affects 10-30% of the population, negatively impacting one's quality of life and productivity. It has been associated with sinusitis, otitis media, sleep disorders, and asthma. Rupatadine is a second generation antihistamine with increased affinity to histamine receptor H1; it is also a potent PAF (platelet-activating factor) antagonist. It starts acting quite quickly, offers long lasting effect, and reduces the chronic effects of rhinitis.

Aim

this study aims to assess the efficacy and safety of rupatadine in the treatment of persistent allergic rhinitis.

Materials and method

this is a multi-centric open prospective study. This study included 241 patients from 13 centers in Brazil and was held between October of 2004 and August of 2005. Signs and symptoms of rhinitis and tolerance to medication were analyzed after one and two weeks of treatment.

Results

reduction on general scores from 8.65 to 3.21 on week 2 (p<0.001). All signs and symptoms improved significantly in the first day of treatment (p<0.001), except for nasal congestion and secretion, which improved from the second day of treatment (p<0.001). Adverse events occurred in 19.9% of the cases, 27.7% on week 1.

Conclusion

rupatadine effectively controls persistent allergic rhinitis; it is safe and presents low incidence of side effects.

Levocetirizine modulates lymphocyte activation in patients with allergic rhinitis

Levocetirizine, a second generation non-sedating antihistamine that blocks the H(1) histamine receptor, may exhibit immunoregulatory properties that augment its primary pharmacological mechanism. To investigate this possibility, 13 Kuwaiti seasonal allergic rhinitis (SAR) patients were treated with levocetirizine for four weeks in comparison with a 7-member placebo-treated control group, followed by clinical evaluation and flow cytometric analysis of peripheral venous blood for inflammatory cell and lymphocyte subpopulation profiles. Relative to the controls, levocetirizine-treated patients exhibited an expected reduction in early phase allergic symptoms, including sneezing (P<0.001), nasal itching (P<0.01), nasal congestion, and running nose (P<0.001); reduced percentages of eosinophils (P<0.05); and three subpopulations of activated T lymphocytes: CD4+CD29+, CD4+CD212+, and CD4+CD54+ (P<0.05). Levocetirizine treatment also correlated with a significant increase in the percentage of CD4+CD25+ T cells (P<0.001). The ability of levocetirizine to reduce percentage representation of cell phenotypes known to contribute to inflammatory tissue damage (eosinophils, CD4+CD29+, CD4+CD212+, and CD4+CD54+) and expand percentages of CD4+CD25+, which may include protective immunoregulatory (Treg) cells, indicates that the drug has pharmacological potential beyond the immediate effects of H(1) histamine-receptor inhibition. Although the present data does not define a therapeutic mechanism, the results reported here establish important trends that may be used to guide future mechanistic examination of immunoregulatory capacity of H(1) inhibitors.

Selective inhibition of Kir currents by antihistamines

In the present study, the effects of antihistamines on inwardly rectifying potassium (Kir) channels expressed in Xenopus oocyte were investigated using two-electrode voltage clamp technique. Firstly, effects of antihistamines on two members of Kir2.0 sub-family, Kir2.1 and Kir2.3 were compared. For antihistamines that selectively block histamine H(1) receptor, the first-generation antihistamines mepyramine and diphenhydramine inhibited Kir2.3 current by 25.0+/-2.9% and 17.3+/-0.7% at concentrations of 100 microM, respectively. In contrast, the second- and third-generation antihistamines astemizole and desloratadine were completely devoid of any inhibitory effect on Kir2.3 current. Histamine H(2) receptor antagonist cimetidine, at 100 microM, failed to inhibit Kir2.3 current. On the other hand, Kir2.1 current was not sensitive to any of these drugs. The mepyramine-induced inhibition of Kir2.3 current was significantly reduced by a single point mutation in Kir2.3 (Kir2.3(I213L)), which enhances Kir2.3-PIP(2) interaction. Secondly, the effect of mepyramine was also tested on Kir3.4*, another member of Kir family. 100 microM mepyramine produced a 30.3+/-4.6% inhibition on Kir3.4* current. These results suggest that the first-generation histamine H(1) receptor antagonists selectively inhibit Kir currents. The inhibitory effect of antihistamines on Kir currents may be involved in their neuronal and cardiac toxic effects caused by drug overdosing.

Rupatadine

Rupatadine (Rupafin, Rinialer, Rupax, Alergoliber) is a selective oral histamine H(1)-receptor antagonist that has also been shown to have platelet-activating factor (PAF) antagonist activity in vitro. It is indicated for use in seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU) in patients aged >/=12 years. Clinical trials show that rupatadine is an effective and generally well tolerated treatment for allergic rhinitis and CIU. It has a rapid onset of action and a prolonged duration of activity. Importantly, it has no significant effect on cognition, psychomotor function or the cardiovascular system. Once-daily rupatadine significantly improves allergic rhinitis symptoms in patients with SAR, PAR or persistent allergic rhinitis (PER) compared with placebo, and provides similar symptom control to that of loratadine, desloratadine, cetirizine or ebastine. In patients with CIU, longer-term use of rupatadine improves CIU symptoms to a greater extent than placebo. It is as well tolerated as other commonly used second-generation H(1)-receptor antagonists. Thus, the introduction of rupatadine extends the range of oral agents available for the treatment of allergic disorders, including allergic rhinitis and CIU.

Effects of rupatadine vs placebo on allergen-induced symptoms in patients exposed to aeroallergens in the Vienna Challenge Chamber

BACKGROUND

Rupatadine is a novel compound with potent dual antihistamine and platelet-activating factor antagonist activities and no sedative effects.

OBJECTIVE

To evaluate the efficacy of rupatadine, 10 mg once daily, and placebo on allergen-induced symptoms (including nasal congestion), nasal airflow, nasal secretion, and subjective tolerability in response to grass pollen in a controlled allergen-exposure chamber.

METHODS

In a randomized, double-blind, placebo-controlled, crossover trial, 45 patients with a history of seasonal allergic rhinitis received rupatadine or placebo every morning for 8 days in 2 different periods separated by a 14-day washout interval. On day 8 of each crossover period, patients underwent a 6-hour allergen exposure in the Vienna Challenge Chamber, where a constant and homogeneous concentration of aeroallergens was maintained. Subjective and objective assessments were performed online during the exposure.

RESULTS

Subjective single and composite nasal and nonnasal symptoms were consistently less severe with rupatadine use than with placebo use starting from the first evaluation at 15 minutes to the end of the 6-hour Vienna Challenge Chamber challenge, with the most significant effects seen for nasal rhinorrhea, nasal itching, sneezing attacks, and total nasal symptoms (P < .001 for all). All the other symptoms (including nasal congestion, P < or = .005) were also significantly reduced with active treatment compared with placebo use. Mean secretion weights and overall feeling of complaint were significantly lower with rupatadine therapy than with placebo use (P < or = .001). Overall, rupatadine treatment was well tolerated.

CONCLUSION

Rupatadine treatment is effective and well tolerated in patients with allergen-induced symptoms exposed to aeroallergens in a controlled exposure chamber.

Activation of connective tissue-type and mucosal-type mast cells in compound 48/80-induced airway response

The pathology of non-immunological airway contraction is not well understood. To define the activation of different phenotypes of mast cells, a rat non-immunological asthmatic model was prepared. Airway contraction in rats was measured by an unrestrained whole-body plethysmographic system following a 10-min inhalation challenge with a 5% solution of compound 48/80. Histamine, leukotrein C(4) (LTC(4)) and tumor necrosis factor (TNF)-alpha levels in bronchoalveolar lavage fluid, as well as tissue histamine content were quantified. Mast cells and eosinophils were detected by histology. Both the early and late phase of airway responses were induced by inhalation of compound 48/80. Histamine and TNF-alpha levels increased significantly 30 min after challenge, but no increases were detected at either 8 or 24 h after challenge. A high LTC(4) level was detected in 30 min and 8 h after challenge. Tissue histamine content decreased at 30 min after challenge and returned to the unstimulated level by 8 h. Connective tissue mast cells in rat trachea showed a degranulation response. Along with the increase in numbers of mucosal mast cells, rat mast cell protease II at both mRNA and protein levels in the trachea epithelial layer was also increased significantly at 30 min after challenge. We conclude that compound 48/80 inhalation causes both the early and late phase of airway contraction in rats. Mast cell degranulation is responsible for the early phase of airway response, which subsequently triggers the late phase of airway response.

Levocetirizine in the treatment of chronic idiopathic urticaria: a randomized, double-blind, placebo-controlled study

BACKGROUND

Chronic urticaria is a common skin condition. It is frequently a disabling disease because of the persistence of clinical symptoms, the unpredictable course and its negative influence on the quality of life.

OBJECTIVES

To determine whether levocetirizine is efficacious in the treatment of chronic idiopathic urticaria.

METHODS

A randomized, double-blind, placebo-controlled study was conducted in 106 patients with a diagnosis of chronic idiopathic urticaria. A 1-week single blind placebo run-in period (baseline) was followed by a 6-week double blind active treatment period. The patients were randomized to receive one of the following treatments once daily: (a) oral levocetirizine 5 mg, or (b) oral placebo. The study ended after another 1-week single blind placebo washout period.

RESULTS

The evaluable population consisted of 100 patients. Levocetirizine administered once daily is effective and well tolerated in the treatment of the symptoms of chronic idiopathic urticaria and in improving the patient's quality of life. Levocetirizine was superior to placebo in reducing the mean total symptoms score as well as individual symptoms, the number of daily episodes and the number of weals, the overall severity of symptoms and the quality of life. The significant beneficial effects of levocetirizine lasted only during the active trial, while at follow-up there was a significant worsening of all the variables evaluated in this study, after the end of the active trial (week 7).

CONCLUSIONS

A global assessment indicates that levocetirizine 5 mg once daily is an effective agent in patients with chronic idiopathic urticaria, as its action provides a rapid and satisfactory control of the symptoms and measures of subjective disease, although this is limited to the duration of treatment.

Nasal congestion model in Brown Norway rats and the effects of some H1-antagonists

The aim of this study was to develop and characterize a new model for evaluating nasal congestion in rats by using whole body plethysmography (WBP)-free moving application. Brown Norway rats were sensitized with 10% toluene-2, 4-diisocyanate (TDI) solution, and nasal congestion was provoked with 5% TDI. An increase in the enhanced pause (Penh) was recognized after being challenged with TDI. In addition, a significant increase in the Penh was observed following the intranasal application of histamine in TDI sensitized rats. Histamine H1 antagonists, such as chlorpheniramine and ketotifen suppressed the increase of Penh during the early-phase response. On the other hand, epinastine suppressed the increase of Penh in both the early and late phase responses. In conclusion, we developed an allergic rhinitis model that includes nasal congestion symptoms in Brown Norway rats, and this model may be useful for evaluating the effects of drugs on nasal congestion.

Roles of histamine and its receptors in allergic and inflammatory bowel diseases

Mast cell has a long history of being recognized as an important mediator-secreting cell in allergic diseases, and has been discovered to be involved in IBD in last two decades. Histamine is a major mediator in allergic diseases, and has multiple effects that are mediated by specific surface receptors on target cells. Four types of histamine receptors have now been recognized pharmacologically and the first three are located in the gut. The ability of histamine receptor antagonists to inhibit mast cell degranulation suggests that they might be developed as a group of mast cell stabilizers. Recently, a series of experiments with dispersed colon mast cells suggested that there should be at least two pathways in man for mast cells to amplify their own activation-degranulation signals in an autocrine or paracrine manner. In a word, histamine is an important mediator in allergic diseases and IBD, its antagonists may be developed as a group of mast cell stabilizers to treat these diseases.

New strategies in the treatment and prevention of allergic diseases

Allergic diseases (AD) are more prevalent today than 30 years ago but over the same period, few novel efficacious drugs have been discovered to treat, control or even cure these disorders. Topical or systemic glucocorticosteroids combined with symptom-relieving medications, such as beta 2 -adrenoceptor agonists, leukotriene inhibitors or antihistamines, are still the mainstay of antiallergic treatment. Modified glucocorticosteroids with less adverse effects, better bronchodilators and new selective mediator inhibitors may improve symptom control in the future. Only specific immunotherapy has shown potential for long-lasting disease-modifying effects. Immunomodulation is a therapeutic goal, aiming to modify the dominant helper T cell Type 2 inflammation to a helper T cell Type 1 response using modified allergens, mycobacteria or CpG oligodeoxynucleotides. Humanised monoclonal anti-IgE antibodies are an exciting new immunomodulatory medication that are expected to reach the clinical practice and have recently been licensed in Australia and the US. Advances in molecular, cellular and genetic research of the immunopathophysiology of AD have led to the development of new antagonists for cytokines, chemokines, receptors, second messengers and transcription factors that may become available for clinical use in the next 10 years. Specific diets supplemented with antioxidants or probiotics need further study but offer promise as safe and cheap preventative medicine. The strong genetic component of AD and the Human Genome Project have opened a new field of research, and modification or replacement of target genes has a curative potential with exciting new therapeutic developments in the years ahead.

Levocetirizine: the allergist’s arsenal grows larger

Antihistamines are the cornerstone of treatment for many allergic diseases, such as allergic rhinitis and chronic urticaria. Since the discovery of their beneficial effects in the 1940s, scientists have found molecules with greater selectivity to block specific histamine receptors without some of the detrimental side effects that are seen if antihistamines cross the blood-brain barrier. Levocetirizine is the active enantiomer of cetirizine and a selective H(1)-histamine blocker. It exhibits many favourable characteristics of an ideal antihistamine, both pharmacodynamically and pharmacokinetically, including high bioavailability, rapid onset of action, limited distribution and low degree of metabolism. Furthermore, clinical trials indicate that it is safe and effective for the treatment of allergic rhinitis and chronic urticaria with a minimal amount of untoward effects.

Anti-inflammatory properties of desloratadine

BACKGROUND

Allergic rhinitis (AR) is associated with robust infiltration of immune cells and mediators that may contribute to clinical manifestations of the disease.

OBJECTIVE

To review the complex immune effector mechanisms involved in the allergic response and discuss their effects on the pathophysiological and clinical manifestations of AR. Desloratadine, a novel antihistamine, was used as a probe with the goal of attaining a better understanding of the inflammatory processes underlying the allergic response.

METHODS

Data were obtained from abstracts and peer-reviewed journals. The pathophysiology of the allergic response has been extensively studied. This paper presents only data from studies that used desloratadine at physiologically relevant concentrations.

RESULTS

Key mediators involved in the allergic response and in pathophysiological and clinical manifestations of the immune response were reviewed. Desloratadine was used as a probe to further elucidate the mechanisms involved during an allergic response.

CONCLUSIONS

Some have proposed a link between the pathophysiology of AR and the clinical manifestation of symptoms. Desloratadine, a new-generation antihistamine, has demonstrated anti-inflammatory effects in vitro; indeed, desloratadine is capable of intervening at various points in the immune cascade. Although in vitro results do not necessarily correlate with clinical efficacy, the anti-inflammatory properties of desloratadine may contribute to its efficacy in patients with AR, allergy-induced asthma, and other related allergic conditions. Antihistamines that modulate in the immune system at various stages may optimize treatment of allergic disease.

Desloratadine: an update of its efficacy in the management of allergic disorders

Desloratadine (Clarinex, Neoclarityn, Aerius, Azomyr, Opulis, Allex), the principal metabolite of loratadine, is itself an orally active, nonsedating, peripheral histamine H(1)-receptor antagonist. It is indicated in the US and Europe for the treatment of seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU). It has a rapid onset of effect, efficacy throughout a 24-hour dosage interval, and sustained efficacy in these allergic conditions, as demonstrated in placebo-controlled trials of up to 6 weeks' duration in adult and adolescent patients. At present, there are no published direct comparisons of desloratadine and other H(1)-antihistamines; however, the principal, potential clinical advantages of desloratadine over late-generation H(1)-antihistamines are the drug's decongestant activity, which has been corroborated in several studies of patients with allergic rhinitis, and its anti-inflammatory effects. Indeed, the decongestant activity of desloratadine did not differ from that of pseudoephedrine in a trial in patients with SAR, and in patients with SAR and coexisting asthma, desloratadine reduced asthma symptoms and beta(2)-agonist use, and improved forced expiratory flow in 1 second. However, these issues warrant further study. Desloratadine is generally well tolerated. The overall incidence of adverse events in adults, adolescents and children was not significantly different to that with placebo, and similar proportions of desloratadine or placebo recipients reported events such as pharyngitis, dry mouth, myalgia, somnolence, dysmenorrhoea or fatigue. Desloratadine does not cause sedation or prolong the corrected QT (QTc) interval, can be administered without regard to concurrent intake of food and grapefruit juice, and appears to have negligible potential for drug interactions mediated by several metabolic systems.

CONCLUSION

Although comparative studies with second-generation and other recently developed H(1)-antihistamines are needed to define the drug's clinical profile more clearly, desloratadine can be expected to claim a prominent place in the management of allergic disorders in general, and in the amelioration of specific symptoms of allergy (e.g. nasal congestion) in patients with such disorders.

Treatment of allergic rhinitis

Allergic rhinitis, a common and often debilitating disease marked by rhinorrhea, nasal congestion, nasal itching, and sneezing, is on the increase worldwide. Treatment involves allergen avoidance, pharmacotherapy, and, in selected cases, immunotherapy. This overview describes the characteristics, pathogenesis, and diagnosis of allergic rhinitis. The major contributing allergens of seasonal and perennial allergic rhinitis are identified. Pharmacotherapy is described within the context of treatment guidelines developed by the major asthma and allergy professional organizations. Oral H1 antihistamines are first-line therapy for mild-to-moderate allergic rhinitis. The newer, nonsedating agents are recommended over first-generation antihistamines. Some of the newer oral antihistamines, such as cetirizine, desloratadine, and fexofenadine, have been shown to relieve the symptom of nasal congestion. Intranasal steroids are first-line therapy for patients with more severe symptoms.

Emerging safety issues regarding long-term usage of H(1)receptor antagonists

The second generation histamine H(1)-receptor antagonists are important therapeutic tools in the treatment of atopic disease and may also have a place as an adjunct therapy for those patients whose allergic asthma coexists with allergic rhinitis. They are amongst the most widely prescribed and safest drugs in the world. However, as second generation H(1)-receptor antagonists are used to treat non-life threatening conditions, the risk of adverse effects is of vital importance. For many, the potential for sedation by some of the newer antihistamines still remains an issue, while there have recently been widespread concerns regarding the potential for cardiotoxicity and the impact of drug-drug interactions associated with some second generation H(1)-receptor antagonists. Consequently, progress with this class of drugs should involve not only increased efficacy but also improvements in their safety and specificity. Moreover, there is a trend towards using second generation H(1)-receptor antagonists as long-term therapy rather than confining their use to treating the short-term manifestations of allergic disease. To this end, a number of novel, potent and safe antihistamines have been developed which are either metabolites of active drugs or enantiomers. This review will examine some of the safety issues associated with established and newer second generation drugs particularly in relation to their long-term usage in adults and children.