Effects of H1 antihistamines on adhesion molecules: a possible rationale for long-term treatment

An opinion on H1-antihistamines as a potential avenue for endometriosis management

Endometriosis is a chronic inflammatory gynecologic condition among women of reproductive age causing a plethora of symptoms that significantly affect their quality of life and mental health. Recent literature reports mounting evidence for several inflammation-mediated pathways for endometriosis pathogenesis, where elevated levels of proinflammatory factors, such as intercellular adhesion molecule 1, tumor necrosis factor-alpha, and nuclear factor kappa B have been established. Simultaneously, the prevalent clinical use of H1-antihistamines for other pathologies along with active research into its action pathways has led to our current understanding that H1-antihistamines counteract several inflammation mediators, including intercellular adhesion molecule 1, tumor necrosis factor-alpha, and nuclear factor kappa B. Although a wide range of existing drug-based endometriosis managements act via the estrogen-dependent pathways, along with some newer ones attempting to use antagonists of targeted inflammation-modulating factors, investigations into the direct use of H1-antihistamines in the context of endometriosis are currently lacking. In this brief perspective opinion essay, correlative evidence has been placed forward that points toward a potential avenue of H1-antihistamines for endometriosis management, and some ideas have been highlighted for future research considerations.

Turbinate Hypertrophy, Allergic Rhinitis, and Otitis Media

PURPOSE OF REVIEW

Otitis media (OM) is a disease with high prevalence in infancy; it has a substantial burden on healthcare resources, and a relevant impact on the quality of life of families. The link between OM and allergic rhinitis (AR) is still debated. However, there is agreement about the relevance of type 2 inflammation on turbinate hypertrophy (TH) generation. There is also evidence that TH is associated with middle ear dysventilation: a pathogenic factor promoting OM. Therefore, a vicious circle among AR, TH, and OM may occur.

RECENT FINDINGS

There are some recent studies exploring this issue through different approaches, such as epidemiological, mechanistic, and therapeutic. Identifying allergy as a pathogenic factor for OM could improve the management of OM patients. Vice versa, suspecting AR in OM patients, could be reasonable in selected patients. The current narrative review provides an overview of the evidence concerning the potential role of AR, and associated TH, in OM patients.

Turbinate Hypertrophy, Allergic Rhinitis, and Otitis Media

PURPOSE OF REVIEW

Otitis media (OM) is a disease with high prevalence in infancy; it has a substantial burden on healthcare resources and a relevant impact on the quality of life of families. The link between OM and allergic rhinitis (AR) is still debated. However, there is agreement about the relevance of type 2 inflammation on turbinate hypertrophy (TH) generation. There is also evidence that TH is associated with middle ear dysventilation: a pathogenic factor promoting OM. Therefore, a vicious circle among AR, TH, and OM may occur.

RECENT FINDINGS

There are some recent studies exploring this issue through different approaches, such as epidemiological, mechanistic, and therapeutic. Identifying allergy as a pathogenic factor for OM could improve the management of OM patients. Vice versa, suspecting AR in OM patients could be reasonable in selected patients. The current narrative review provides an overview of the evidence concerning the potential role of AR, and associated TH, in OM patients.

Antihistamine therapy in allergic rhinitis

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

The pathophysiology, clinical impact, and management of nasal congestion in allergic rhinitis

BACKGROUND

Nasal congestion is a cardinal symptom of allergic rhinitis (AR). It is difficult to treat and is associated with decreased quality of life.

OBJECTIVE

This article reviews the clinical features of nasal congestion, its complex pathophysiology in the context of AR, its clinical impact, and the strengths and weaknesses of available treatments.

METHODS

Primary studies and reviews in the peer-reviewed, English-language literature were identified through searches of MEDLINE (1966-2008) and the Cochrane Library (1996-2008) using the terms nasal congestion, allergic rhinitis, pathophysiology, quality of life, and burden. Additional references were obtained by searching the reference lists of the identified articles. Abstracts from the 2006 and 2007 meetings of the American Academy of Allergy, Asthma, and Immunology were also searched. Pertinent articles were included in the review if they were recently published and patient-focused, and if their authors were recognized leaders in the field.

RESULTS

A survey of 2355 patients with AR or their guardians found that almost half of respondents rated nasal congestion the most bothersome symptom; in a survey of 2500 adults with AR, 78% rated nasal congestion either extremely or moderately bothersome. Histamine and leukotrienes are major mediators of the allergic inflammation associated with nasal congestion, as indicated by reductions in nasal cross-sectional area in response to histamine challenge (P<0.001) and increases in nasal airway resistance in response to leukotriene challenge (P<0.05).Therapy for nasal congestion in AR is often hampered by limitations associated with the individual agents; for example, decongestants are effective in the control of nasal congestion, but their use is restricted by their adverse-event profiles. A meta-analysis of 16 controlled studies involving 2267 patients with AR found that intranasal corticosteroids provided significantly greater relief of nasal congestion than oral antihistamines (95% CI for combined standardized mean difference, -0.73 to -0.53). The results of several clinical trials have suggested that leukotriene-receptor antagonists may be associated with reduced nasal congestion; however, no agents in this class are currently approved for the treatment of nasal congestion in AR.

CONCLUSION

There is a need for therapies that are well tolerated and effective in relieving nasal congestion in AR.

Effect of tecastemizole on pulmonary and cutaneous allergic inflammatory responses

BACKGROUND

Tecastemizole, a major metabolite of astemizole, is a potent and selective H1 receptor antagonist. Evidence suggests that this and certain other H1 receptor antagonists may possess anti-inflammatory effects that are, in some cases, independent of H1 receptor antagonism. Objective The aim of this study was to investigate the anti-inflammatory effects of tectastemizole in models of allergic inflammation.

METHODS

Effects of tecastemizole were assessed in a murine model of allergic lung inflammation, in passive cutaneous anaphylaxis (PCA) responses in guinea-pig skin and in in vitro assays measuring endothelial adhesion molecule expression and leucocyte-endothelial adhesion.

RESULTS

Tecastemizole inhibited antigen-induced eosinophil recruitment to the lungs of allergic mice in a dose-dependent manner. Furthermore, combination of a sub-effective dose of tecastemizole, combined with a sub-effective dose of dexamethasone inhibited eosinophil accumulation in this model. Plasma extravasation in PCA reactions was inhibited by tecastemizole, although by a mechanism that would appear to be H1 receptor-dependent. Cytokine-induced endothelial intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression, as well as mononuclear cell adhesion to human umbilical vein endothelial cells was inhibited by tecastemazole in a manner independent of H1 receptor antagonism.

CONCLUSION

These data suggest that tecastemizole may have H1 receptor-independent effects in inhibiting late-phase inflammatory responses, while acute responses appear to be inhibited in a H1 receptor-dependent manner. Furthermore, our data suggest an important potential steroid-sparing role for such drugs in the treatment of allergic inflammatory conditions.

Emerging anti-inflammatory agents for allergic rhinitis

Allergic rhinitis (AR) is a high-prevalence disease, affecting 10-15% of the general population. AR is sustained by an IgE-mediated reaction, and by a complex inflammatory network of cells, mediators and cytokines that becomes chronic when exposure to allergen persists. A T helper 2 (TH2)-biased immune response is the basis for the allergic inflammation. The current therapeutic strategy is mainly based on drugs (antihistamines, nasal corticosteroids, cromones, decongestants) and allergen immunotherapy. Drugs are overall effective in controlling symptoms, but do not modify the immune background that leads to allergic inflammation, and safety concerns may be present especially for prolonged treatments. Immunotherapy can modify the allergic response, but there is still space for improvement. Nowadays, several approaches are under investigation to optimise the management of AR. On one hand, new drugs and antimediators are being developed; on the other hand, attempts are made to selectively block relevant signal pathways of allergic reaction. Finally, one of the major goals is to modify the TH2-biased immune response by improving the characteristics and modes of action of allergen immunotherapy.

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.

Histamine in allergic inflammation and immune modulation

Histamine, originally considered as a mediator of acute inflammatory and immediate hypersensitivity responses has also been demonstrated to affect chronic inflammation and regulate several essential events in the immune response. On the other hand, various cytokines control histamine synthesis, release and expression of histamine receptors (HRs). The cells involved in the regulation of immune response and hematopoiesis express HRs and also secrete histamine, which can selectively recruit the major effector cells into tissue sites and affect their maturation, activation, polarization and effector functions leading to chronic inflammation. Histamine, acting through its receptor type 2, positively interferes with the peripheral antigen tolerance induced by T regulatory cells in several pathways. Histamine also regulates antigen-specific Th1 and Th2 cells, as well as related antibody isotype responses. The diverse effects of histamine on immune regulation are due to differential expression and regulation of four HRs and their distinct intracellular signals. In addition, differences in affinities of these receptors are highly decisive on the biological effects of histamine and agents that target HRs. This article highlights the findings leading to a change of perspective in histamine immunobiology.

The effect of ketotifen on inflammatory markers in allergic conjunctivitis: an open, uncontrolled study

BACKGROUND

The efficacy and safety of ketotifen eye drop treatment in allergic conjunctivitis (AC) management is perfectly known by several studies, but the mechanism of action at the biochemical levels is poorly understood so we decided to perform an open, uncontrolled study in order to investigate the effect of the topical administration of ketotifen fumarate 0.05% on biochemical markers of inflammation on conjunctival cells in patients with AC.

METHODS

Nineteen patients with symptoms and signs of AC (itching, discharge, burning, redness, increase in the watery discharge, swelling and follicles) and with a history of allergy were prescribed with two daily instillation of one drop of eyewash ketotifen fumarate 0,05% in both eyes during thirty days. They were studied by measuring clinical and immunologic parameters.

RESULTS

Ketotifen fumarate treatment significantly reduced the total symptoms and signs score for each patient as well as each symptoms and signs at all time points compared with day 0 (p < 0.0001 and p < 0.016, respectively). Although the percentage of HLA-DR+ epithelial cells diminished only in 58% of patients, the numbers of CD29+ and eotaxin+ epithelial cells dropped significantly in 68% and 73 % of them (p < 0.0062 and <0.0082, respectively) as a consequence of the treatment. In 9 out of 19 patients a simultaneous decrease in the percentage of epithelial cells positive for CD29 and eotaxin was observed.

CONCLUSION

Ketotifen besides the well-known effect in reducing signs and symptoms of AC significantly diminished production of eotaxin and expression of CD29 by epithelial cells in patients with seasonal AC.

Atopy: a patient-specific risk factor for diffuse lamellar keratitis

OBJECTIVE

To identify whether atopy is a patient-specific risk factor for the development of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

DESIGN

Retrospective survey study.

PARTICIPANTS

Three hundred sixty consecutive patients who underwent same-day bilateral myopic astigmatic primary LASIK procedures during March 1, 2000, through July 31, 2000.

METHODS

We collected data for 360 consecutive patients undergoing LASIK during a 4-month period. On preoperative medical history questionnaires, patients self-identified whether they were atopic. All patients also indicated whether they were taking antiallergy medications or were untreated for allergy.

MAIN OUTCOME MEASURES

The incidence of DLK after LASIK surgery.

RESULTS

The risk of DLK in untreated atopic patients was much greater than the risk of DLK among nonatopics (odds ratio, 5.85; 95% confidence interval, 2.89-11.85; P = 0.001). However, the risk of DLK among atopic patients taking an oral systemic nonsedating histamine receptor 1 antagonist and among nonatopic patients did not differ significantly (odds ratio, 0.54; 95% confidence interval, 0.12-2.46; P = 0.43).

CONCLUSIONS

Atopy is a patient-specific risk factor for the development of DLK after primary bilateral LASIK for either myopia or myopic astigmatism. Atopic individuals benefit from preoperative treatment to minimize the incidence of DLK and the potential for visual loss.

Comparative pharmacology of H1 antihistamines: clinical relevance

H1 antihistamines have similar efficacy in the treatment of allergic disorders; however, they differ in terms of their chemical structure, clinical pharmacology, and safety. This review focuses on the clinical pharmacology (pharmacokinetics and pharmacodynamics) of the newer oral H1 antihistamines (acrivastine, cetirizine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, and mizolastine). Understanding the pharmacokinetics and pharmacodynamics of these H1 antihistamines provides an objective basis for selection of appropriate dosages and dose intervals. Pharmacokinetic and pharmacodynamic studies provide a rationale for the modified dosage regimens that may be required in special populations, such as the very young, the elderly, those with hepatic or renal dysfunction, or those taking other medications concurrently. Many H1 antihistamines are currently available for use. Clinical pharmacology studies help physicians to select the best H1 antihistamines for their patients.

Fexofenadine in chronic idiopathic urticaria: a clinical and immunohistochemical evaluation

Fexofenadine is a non-sedating selective third-generation antihistamine, which also exerts an anti-inflammatory action. The aim of this study was to evaluate the influence on the expression of inflammatory skin mediators, together with the efficacy and tolerability, of fexofenadine in chronic idiopathic urticaria (CIU). Fexofenadine 180mg was administered once daily for 4 weeks after a placebo run-in phase of 3 to 7 days. Efficacy paramaters were obtained from patients' assessment of urticaria symptoms. Non-lesional skin of patients with active CIU was studied immunohistochemically before and after treatment. The expression of the following mediators was evaluated: adhesion molecules (ICAM-1, ELAM-1, VCAM-1); mast cell proteases (chymase and tryptase) and proinflammatory cytokines (IL-1beta, IL-3, IL-6 and TNF-alpha). Of the 20 subjects enrolled, 3 dropped out of the study. Treatment proved successful in most cases (88.2%) (p <0.01) and a significant improvement of all symptoms was registered. Treatment was well-tolerated by all patients; adverse events, neither serious nor drug-related, occurred in any case. Immunochemistry revealed at the baseline a significant expression of ELAM-1, VCAM-1, tryptase, chymase, and TNF-alpha (p= 0.05) in non-lesional skin of patients compared to normal controls. After treatment with fexofenadine, there was a significant decrease in the expression of ELAM-1 (p= 0.02), VCAM-1 (p= 0.04) and tryptase (p= 0.04), whereas no relevant change was observed for the other parameters examined. This work confirms the efficacy and tolerability of fexofenadine HCl 180mg in CIU. These preliminary data show a trend towards a decrease in the expression of tryptase and some adhesion molecules after treatment, suggesting an anti-inflammatory activity of fexofenadine.

Steroid and antihistamines modulate RANTES release in cultured peripheral blood mononuclear cells of atopic patients

RANTES plays a crucial role in cell recruitment in allergic inflammation. We investigated the pharmacological modulation of RANTES release in cultured peripheral blood mononuclear cells obtained from allergic patients with active asthma. Chemokine production was assessed before and after 15 day treatment with histamine-1 receptor antagonists (antihistamines) (Loratadine or Cetirizine) and a steroid (Deflazacort), both in unstimulated and PHA-stimulated cell cultures. Results were compared with those obtained from placebo-treated patients. During the treatment period, patients recorded morning and evening peak expiratory flow (PEF) by the mini-Wright procedure. PEF absolute values and diurnal variability significantly improved respect to the pre-treatment in steroid-treated patients, in comparison to the placebo and antihistamine-treated groups (p&#x003C;0.001 and 0.01, respectively). PEF diurnal variability in the antihistamine-treated group were lower than placebo-treated group without statistical significance (p=0.06). No differences could be found in RANTES levels in supernatants of all cultures between the two antihistamines. RANTES release significantly decreased in supernatants of all cell cultures from steroid (p&#x003C;0.01) and antihistamine (p=0.03 and 0.04) groups after treatments, compared to the basal values; whereas it increased slightly in controls. Co-variance analysis on RANTES levels, adjusting for pre-treatment values, showed a significant reduction of RANTES release by PHA-stimulated PBMCs from steroid (p=0.003) and anti-histamine (p=0.03) groups, with respect to the placebo group. The same statistical tool applied between the steroid and the antihistamine groups showed, after therapy, the lowest levels of RANTES to be associated with steroid treatment (p=0.005). The study shows that the steroid is the most effective drug in modulating RANTES release from PBMCs. However, antihistamines, which are able to reduce cell recruitment due to chemokine release, avoiding important side effects, may be useful in long term therapy in controlling and preventing allergic inflammation.

Drugs, inflammation and cell adhesion receptors

The cell adhesion receptors that participate in the extravasation and migration of leucocytes towards inflammatory foci mainly include the selectins and different members of the integrin and immunoglobulin superfamilies. These adhesion receptors mediate the sequential steps of leucocyte-endothelial cell interaction and, together with chemoattractant molecules (e.g., chemokines), direct the influx of inflammatory cells and define the characteristics of the cell infiltrate. Many different drugs, including non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, rheumatoid arthritis disease-modifying agents and phosphodiesterase inhibitors, interfere with the expression and/or function of cell adhesion receptors and this effect accounts for, at least in part, their anti-inflammatory activity. In recent years, novel approaches for the modulation of the cell membrane receptors involved in inflammation have been active areas in pharmaceutical research. Upgraded synthetic blocking compounds, chimeric monoclonal antibodies or improved antisense oligonucleotides represent important advances in this field. The proper development of these novel approaches, as well as other alternative strategies, will allow a better and more specific pharmacological modulation of the inflammatory phenomenon.

The role of patient training in the management of seasonal rhinitis and asthma: clinical implications

BACKGROUND

Allergic rhinitis is an inflammatory disease often associated with bronchial asthma. Intranasal corticosteroids and oral antihistamines are the first-choice drugs. Patient training is relevant to asthma management, but little is known about its impact on rhinitis. We evaluated the role of patient training in the treatment of allergic rhinitis and its effects on nasal and bronchial symptoms.

METHODS

One hundred and one patients (M/F = 62/39, age range 12-62 years) with pollen-induced rhinitis (32 with concomitant mild asthma) were enrolled. They were randomized into three groups: A (n = 30) with drug therapy alone, B (n = 35) with drug therapy plus training on the use of nasal spray, and C (n = 36) the same as B plus a lesson on rhinitis and asthma. All patients received mometasone furoate nasal spray for 8 weeks as regular therapy, plus rescue medications on demand. Symptoms and drug consumption were evaluated during the pollen season.

RESULTS

The rate of noncompliance/dropout was highest in the untrained patients (P = 0.001). No difference in nasal symptoms was seen among the three groups. On the other hand, group C had significantly fewer asthma symptoms (P = 0.02) and less albuterol use (P = 0.005) than group A. Moreover, the trained group globally used less rescue medication than the other groups (P = 0.02).

CONCLUSIONS

Detailed training of patients seems to improve compliance with treatment, reduce concomitant asthma symptoms, and reduce the use of symptomatic drugs.

COX-2 inhibitors vs. NSAIDs in gastrointestinal damage and prevention

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit production of protective gastric mucosal prostaglandins and also have a direct topical irritant effect. In some patients this results in dyspepsia and development of gastroduodenal erosions and ulceration. The risk of ulcer complications, such as bleeding, perforation and death is increased approximately 4-fold in NSAID users. Patients at high risk of ulcer complications include the elderly, those taking anticoagulants, steroids and aspirin, those with a previous history of peptic ulceration and patients with concomitant serious medical problems. The interaction of NSAIDs with Helicobacter pylori (the major cause of peptic ulceration in non-NSAID users) is controversial and some studies suggest that H. pylori infection may even protect against NSAID-induced ulceration. Selective inhibitors of the inducible cyclooxygenase-2 (COX-2) enzyme spare COX-1 in the gastric mucosa and, hence, do not inhibit production of mucosal prostaglandins. COX-2-selective inhibitors are associated with a significant reduction in gastroduodenal damage compared with traditional NSAIDs. Proton pump inhibitors (PPI) are probably the best agents for healing and prevention of NSAID-induced ulcers. Preliminary studies suggest that COX-2 selective inhibitors, like traditional NSAIDs, may prevent lower gastrointestinal cancer. Further studies are needed but they may be useful in individuals at high risk of certain types of lower gastrointestinal malignancy with increased gastrointestinal tolerability and safety.

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.