Comparative effects of topical ocular anti-allergy drugs on human conjunctival mast cells

Assessment of receptor affinities of ophthalmic and systemic agents in dry eye disease

PURPOSE OF REVIEW

To explore our current understanding of receptor profiles acted upon by medications used to treat dry eye disease (DED).

RECENT FINDINGS

Research into histaminic and muscarinic receptor affinities for drugs targeting the ocular surface has not kept up with bench research pertaining to the receptor profile of the ocular surface. These insights are necessary for better evaluation of medications used in DED and other allergic disorders.

SUMMARY

At the H1 receptor, Ketotifen (pKa = 9.2), pyrilamine (pKa = 9.0), and epinastine (pKa = 8.0) had the highest affinities, whereas ranitidine (pKa = 4.2) and cimetidine (pKa = 4.9) had the lowest. Ketotifen, a second-generation antihistamine, was found to have a pKa of 6.7 at muscarinic receptors which was higher than that of diphenhydramine (pKa = 6.4), a first-generation antihistamine. Additionally, second-generation antihistamines have higher affinity for H3 receptors, which have been linked to urticaria, compared to first-generation. Azelastine, a second-generation, demonstrated significant affinity (pKa = 7.1) at the H3 receptor compared to all other drugs. Antazoline (pKa = 4.4) and diphenhydramine (pKa = 4.6), both first-generation antihistamines, had the lowest affinities for the H3 receptor. These findings raise questions about the use of antihistamines in the treatment of DED and allergic disorders.

Combine therapy as a modern approach to treatment of allergic rhinitis

Allergic rhinitis (AR) is one the most common allergic diseases affecting from 10 to 40% of the population in different countries, including Russia. AR is a risk factor of bronchial asthma, other upper airway disease and may decrease patient quality of life, their productivity, increase probability of occupational traumatism, depression and anxiety. AR also presents a substantial economic burden. The rationale to use fixed dose combination of intranasal steroids and topical H1 antihistamines includes suboptimal control of symptoms by monotherapy, its complementary pharmacologic activity and the results of clinical trials. This review focused on fixed dose combination of intranasal mometasone furoate and olopataine. Double blind placebo-controlled and open clinical trials have confirmed that this combination decreased severity of nasal and ocular symptoms of seasonal and perennial AR, improved patient quality of life and had a good tolerability. Its efficacy was higher than those of monotherapy. Fast onset of action and sustainable effect on symptoms (during 1 yr) may improve adherence patients to the treatment and control of symptoms of AR.

Discovery to Launch of Anti-allergy (Emadine; Patanol/Pataday/Pazeo) and Anti-glaucoma (Travatan; Simbrinza) Ocular Drugs, and Generation of Novel Pharmacological Tools Such as AL-8810

The eye and eyesight are exquistly designed and are precious, and yet we often take them for granted. Good vision is critical for our long-term survival and for humanity's enduring progress. Unfortunately, since ocular diseases do not culminate in life-and-death scenarios, awareness of the plight of millions of people suffering from such eye ailments is not publicized as other diseases. However, losing eyesight or falling victim to visual impairment is a frightening outlook for most people. Glaucoma, a collection of chronic optic neuropathies, of which the most prevalent form, primary open-angle glaucoma (POAG), is the second leading cause of irreversible blindness. POAG currently afflicts >70 million people worldwide and is an insidious, progressive, silent thief of sight that is asymptomatic. On the other hand, allergic conjunctivitis (AC), and the associated rhinitis ("hay-fever"), frequently victimizes a huge number of people worldwide, especially during seasonal changes. While not life-threatening, sufferers of AC soon learn the value of drugs to treat their signs and symptoms of AC as they desire rapid relief to overcome the ocular itching/pain, redness, and tearing AC causes. Herein, I will describe the collective efforts of many researchers whose industrious, diligent, and dedicated team work resulted in the discovery, biochemical/pharmacological characterization, development and eventual launch of drugs to treat AC (e.g., olopatadine [Patanol/Pataday/Pazeo] and emedastine [Emedine]), and for treating ocular hypertension and POAG (e.g., travoprost [Travatan ] and Simbrinza). This represents a personal perspective.

Histamine-mediated autocrine signaling in mesenteric perilymphatic mast cells

Lymphatic vessels play a critical role in mounting a proper immune response by trafficking peripheral immune cells to draining lymph nodes. Mast cells (MCs) are well known for their roles in type I hypersensitivity reactions, but little is known about their secretory regulation in the lymphatic niche. MCs, as innate sensor and effector cells, reside close to mesenteric lymphatic vessels (MLVs), and their activation and ability to release histamine influences the lymphatic microenvironment in a histamine-NF-κB-dependent manner. Using an established experimental protocol involving surgical isolation of rat mesenteric tissue segments, including MLVs and surrounding perilymphatic tissues, we tested the hypothesis that perilymphatic mesenteric MCs possess histamine receptors (HRs) that bind and respond to the histamine released from these same MCs. Under various experimental conditions, including inflammatory stimulation by LPS, we measured histamine in mesenteric perilymphatic tissues, evaluated expression of histidine decarboxylase in MCs along with the degree of MC degranulation, assessed the functional status of HRs in MCs, and evaluated the ability of histamine itself to induce MC activation. Finally, we evaluated the importance of MCs and HR1 and -2 for MLV-directed trafficking of CD11b/c-positive cells during acute tissue inflammation. Our data indicate the existence of a functionally potent MC-histamine autocrine regulatory loop, the elements of which are crucially important for acute inflammation-induced trafficking of the CD11b/c-positive cells toward MLVs. This MC-histamine loop serves as a first-line cellular servo control system, playing a key role in the innate and adaptive immune response as well as NF-κB-mediated maintenance of body homeostasis.

Projected 24-hour post-dose ocular itching scores post-treatment with olopatadine 0.7% versus 0.2

Olopatadine is an antihistamine and mast cell stabilizer used for treating allergic conjunctivitis. Olopatadine 0.7% has been recently approved for daily dosing in the US, which supersedes the previously approved 0.2% strength. The objective of this analysis was to characterize patients who have better itching relief at 24 h when taking olopatadine 0.7% treatment instead of olopatadine 0.2% (in terms of proportions of responses) and relate this to the severity of baseline itching as an indirect metric of a patient’s sensitivity to antihistamines. A differential odds model was developed using data from two conjunctival allergen challenge (CAC) studies to characterize individual-level and population-level response to ocular itching following olopatadine treatment and the data was analyzed retrospectively. This modeling analysis was designed to predict 24 h ocular itching scores and to quantify the differences in 24 h itching relief following treatment with olopatadine 0.2% versus 0.7% in patients with moderate-to-high baseline itching. A one-compartment kinetic-pharmacodynamic E_max model was used to determine the effect of olopatadine. Impact of baseline itching severity, vehicle effect and the drug effect on the overall itching scores post-treatment were explicitly incorporated in the model. The model quantified trends observed in the clinical data with regards to both mean scores and the proportions of patients responding to olopatadine treatment. The model predicts a higher proportion of patients in the olopatadine 0.7% versus 0.2% group will experience relief within 24 h. This prediction was confirmed with retrospective clinical data analysis. The number of allergy patients relieved with olopatadine 0.7% increased with higher baseline itching severity scores, when compared to olopatadine 0.2%.

Age-related Defects in Ocular and Nasal Mucosal Immune System and the Immunopathology of Dry Eye Disease

Dry eye disease (DED) is a prevalent public health concern that affects up to 30% of adults and is particularly chronic and severe in the elderly. Two interconnected mechanisms cause DED: (1) an age-related dysfunction of lacrimal and meibomian glands, which leads to decreased tear production and/or an increase in tear evaporation; and (2) an age-related uncontrolled inflammation of the surface of the eye triggered by yet-to-be-determined internal immunopathological mechanisms, independent of tear deficiency and evaporation. In this review we summarize current knowledge on animal models that mimic both the severity and chronicity of inflammatory DED and that have been reliably used to provide insights into the immunopathological mechanisms of DED, and we provide an overview of the opportunities and limitations of the rabbit model in investigating the role of both ocular and nasal mucosal immune systems in the immunopathology of inflammatory DED and in testing novel immunotherapies aimed at delaying or reversing the uncontrolled age-related inflammatory DED.

Antihistamines suppress upregulation of histidine decarboxylase gene expression with potencies different from their binding affinities for histamine H1 receptor in toluene 2,4-diisocyanate-sensitized rats

Antihistamines inhibit histamine signaling by blocking histamine H1 receptor (H1R) or suppressing H1R signaling as inverse agonists. The H1R gene is upregulated in patients with pollinosis, and its expression level is correlated with the severity of nasal symptoms. Here, we show that antihistamine suppressed upregulation of histidine decarboxylase (HDC) mRNA expression in patients with pollinosis, and its expression level was correlated with that of H1R mRNA. Certain antihistamines, including mepyramine and diphenhydramine, suppress toluene-2,4-diisocyanate (TDI)-induced upregulation of HDC gene expression and increase HDC activity in TDI-sensitized rats. However, d-chlorpheniramine did not demonstrate any effect. The potencies of antihistamine suppressive effects on HDC mRNA elevation were different from their H1R receptor binding affinities. In TDI-sensitized rats, the potencies of antihistamine inhibitory effects on sneezing in the early phase were related to H1R binding. In contrast, the potencies of their inhibitory effects on sneezing in the late phase were correlated with those of suppressive effects on HDC mRNA elevation. Data suggest that in addition to the antihistaminic and inverse agonistic activities, certain antihistamines possess additional properties unrelated to receptor binding and alleviate nasal symptoms in the late phase by inhibiting synthesis and release of histamine by suppressing HDC gene transcription.

Advances in pharmacotherapy for allergic conjunctivitis

INTRODUCTION

Allergy is the fifth leading group of chronic diseases, affecting as much as 40% of the first-world population. Its pathophysiology has a genetic component, and is driven by the immune system's sensitized response to antigens and environmental factors. As research continues to uncover the mediators responsible for ocular allergy, the development of novel drugs should progress.

AREAS COVERED

A literature review of allergic conjunctivitis, ocular allergy and their treatment was performed using PubMed and Medline. Additional information is also included from clinicaltrials.gov and associated web sites for drugs currently in clinical trials.

EXPERT OPINION

The initial step of therapy remains identification and avoidance of allergic triggers. The mainstay of treatment is the new generation of dual-acting antihistamines. Drugs that improve the magnitude and duration of relief, with greater subject responder rates, are gradually making their way into the clinic. Allergic conjunctivitis is a relatively easy disease to study because of the availability of models such as the conjunctival allergen challenge. New classes of drugs that target inflammatory pathways or mediators involved in the early and late-phase allergic response are being screened in these models and we are making progress in identifying the next generation of anti-allergic therapy.

Ocular allergy: recognizing and diagnosing hypersensitivity disorders of the ocular surface

Ocular allergy includes several clinically different conditions that can be considered as hypersensitivity disorders of the ocular surface. The classification of these conditions is complex, and their epidemiology has not been adequately studied because of the lack of unequivocal nomenclature. Ocular allergy symptoms are often, but not always, associated with other allergic manifestations, mostly rhinitis. However, specific ocular allergic diseases need to be recognized and managed by a team that includes both an ophthalmologist and an allergist. The diagnosis of ocular allergy is usually based on clinical history and signs and symptoms, with the support of in vivo and in vitro tests when the identification of the specific allergic sensitization is required for patient management. The aims of this Task Force Report are (i) to unify the nomenclature and classification of ocular allergy, by combining the ophthalmology and allergy Allergic Rhinitis and its Impact on Asthma criteria; (ii) to describe current methods of diagnosis; (iii) to summarize the therapeutic options for the management of ocular allergic inflammation.

Loteprednol etabonate suspension 0.2% administered QID compared with olopatadine solution 0.1% administered BID in the treatment of seasonal allergic conjunctivitis: a multicenter, randomized, investigator-masked, parallel group study in Chinese patients

BACKGROUND

Seasonal allergic conjunctivitis (SAC) is caused by seasonal allergens and usually manifests as ocular itching and bulbar conjunctival injection (redness). Treatment options for SAC include corticosteroids and dual-acting antihistamine and mast-cell stabilizers.

OBJECTIVE

Our objective was to compare the efficacy and tolerability of loteprednol etabonate (LE), a C-20 ester-based corticosteroid, with those of olopatadine, a dual-acting antihistamine mast-cell stabilizer, in Chinese patients.

METHODS

This was a multicenter, randomized, investigator-masked, parallel group study. Patients with acute SAC experiencing grade 4 ocular itching and grade 2 or higher bulbar conjunctival injection received either LE suspension 0.2% QID at 4-hour intervals or olopatadine solution 0.1% BID at 6- to 8-hour intervals bilaterally for 15 days. Primary efficacy end points included the change from baseline (CFB) in ocular itching and bulbar conjunctival injection at day 15. The primary analysis tested the noninferiority of LE suspension 0.2% to olopatadine solution 0.1%. Tolerability outcomes included the incidence of adverse events (AEs), biomicroscopy findings, visual acuity, and intraocular pressure.

RESULTS

A total of 300 patients were randomly assigned, and 293 were included in the per-protocol population (LE, n = 147; olopatadine, n = 146). Mean (SD) CFB at day 15 in the LE and olopatadine treatment groups, respectively, was -3.74 (0.47) and -3.28 (0.91) for ocular itching and -1.91 (0.52) and -1.71 (0.59) for bulbar conjunctival injection. The 95% CI for the differences in CFB in ocular itching (-0.59 to -0.27) and bulbar conjunctival injection (-0.27 to -0.08) was less than the prespecified noninferiority limit of 0.3. Treatment differences in CFB were significantly better with LE compared with olopatadine for both end points (P ≤ 0.0006). Ocular AEs were few and similar between treatment groups. There were no clinically significant biomicroscopy or visual acuity findings, and no patient experienced a clinically significant increase in intraocular pressure (≥10 mm Hg).

CONCLUSION

Results of this investigator-masked study with Chinese patients suggest LE suspension 0.2% was noninferior to olopatadine solution 0.1% for the treatment of SAC. Both LE suspension 0.2% and olopatadine solution 0.1% were well tolerated. ClinicalTrials.gov identifier: NCT01435460.

Olopatadine ophthalmic solution suppresses substance P release in the conjunctivitis models

Background

Olopatadine hydrochloride ophthalmic solutions are treated for allergic conjunctival diseases that are a selective histamine H1 receptor antagonist and an inhibitor of the release of mediators including histamine from the human mast cells. Substance P (SP) levels are increased in tears of patients with allergic conjunctivitis. However, little is known about the regulation of SP release by anti-allergic ophthalmic solutions.

Objective

We investigated that the effect of olopatadine hydrochloride ophthalmic solutions (olopatadine 0.1% and olopatadine 0.2%) on rat conjunctivitis models compared with other anti-allergic ophthalmic solutions.

Methods

Conjunctivitis was induced by subconjunctival injection of histamine or intravenous injection of ovalbumin in rats passively sensitized with anti-ovalbumin anti-serum. The releases of SP were determined in the conjunctiva and tears using rat antigen-induced conjunctivitis models.

Results

Olopatadine 0.1% and 0.2% significantly inhibited the increased conjunctival dye leaked in the histamine- or antigen-induced hyperpermeability. The inhibitory effects by olopatadine were more potent than by other tested anti-allergic ophthalmic solutions. Moreover, olopatadine significantly inhibited the release of SP from the conjunctiva.

Conclusion

These results indicate that olopatadine ophthalmic solutions appear to exert additional SP release inhibition besides dual-action such as selective histamine H1 receptor antagonistic action and mast cell stabilization action.

Olopatadine hydrochloride and rupatadine fumarate in seasonal allergic rhinitis: A comparative study of efficacy and safety

Objective:

To compare the efficacy and safety of olopatadine and rupatadine in seasonal allergic rhinitis (SAR).

Materials and Methods:

A 2-week, single-centered, randomized, open, parallel group comparative clinical study was conducted on patients with SAR. Following inclusion and exclusion criteria, 70 patients were recruited and were randomized to two treatment groups and received the respective drugs for 2 weeks. At follow-up, clinical improvement was assessed in terms of change in total and differential count of leucocytes, serum Immunoglobulin E (IgE) level, Total Nasal Symptom Score (TNSS) and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scoring.

Results:

Both the drugs significantly reduced the differential count (P<0.001) and absolute eosinophil count (P<0.001), but olopatadine was found to be superior. In olopatadine group, there was significantly higher reduction in serum IgE (P=0.01), TNSS (P<0.001) and RQLQ score (P=0.015) than that of rupatadine. Incidence of adverse effects was found to be less in olopatadine group when compared with rupatadine group.

Conclusions:

Olopatadine is a better choice in SAR in comparison to rupatadine due to its better efficacy and safety profile.

Treatment of allergic conjunctivitis with olopatadine hydrochloride eye drops

Olopatadine hydrochloride exerts a wide range of pharmacological actions such as histamine H₁ receptor antagonist action, chemical mediator suppressive action, and eosinophil infiltration suppressive action. Olopatadine hydrochloride 0.1% ophthalmic solution (Patanol^®) was introduced to the market in Japan in October 2006. In a conjunctival allergen challenge (CAC) test, olopatadine hydrochloride 0.1% ophthalmic solution significantly suppressed ocular itching and hyperemia compared with levocabastine hydrochloride 0.05% ophthalmic solution, and the number of patients who complained of ocular discomfort was lower in the olopatadine group than in the levocabastine group. Conjunctival cell membrane disruption was observed in vitro in the ketotifen fumarate group, epinastine hydrochloride group, and azelastine hydrochloride group, but not in the olopatadine hydrochloride 0.1% ophthalmic solution group, which may potentially explain the lower discomfort felt by patients on instillation. Many other studies in humans have revealed the superiority of olopatadine 0.1% hydrochloride eye drops to several other anti-allergic eye drops. Overseas, olopatadine hydrochloride 0.2% ophthalmic solution for a once-daily regimen has been marketed under the brand name of Pataday^®. It is expected that olopatadine hydrochloride ophthalmic solutions may be used in patients with a more severe spectrum of allergic conjunctival diseases, such as vernal keratoconjunctivitis or atopic keratoconjunctivitis, in the near future.

The effects of the nasal antihistamines olopatadine and azelastine in nasal allergen provocation

BACKGROUND

Olopatadine, an antihistamine used in allergic conjunctivitis, is under development as a nasal preparation for the treatment of allergic rhinitis.

OBJECTIVES

To evaluate the efficacy of olopatadine in suppressing symptoms and biomarkers of the immediate reaction induced by nasal allergen provocation and to compare olopatadine with azelastine in the same model.

METHODS

The study was approved by the Johns Hopkins University institutional review board, and all subjects gave written consent. We studied 20 asymptomatic subjects with seasonal allergic rhinitis. The study had 2 randomized, double-blind, placebo-controlled, crossover phases that evaluated 2 concentrations of olopatadine, 0.1% and 0.2%. In a third exploratory phase, olopatadine, 0.1%, was compared with topical azelastine, 0.1%, in a patient-masked design. Efficacy variables were the allergen-induced sneezes, other clinical symptoms, and the levels of histamine, tryptase, albumin, lysozyme, and cysteinyl-leukotrienes (third study only) in nasal lavage fluids.

RESULTS

Both concentrations of olopatadine produced significant inhibition of all nasal symptoms, compared with placebo. Olopatadine, 0.1%, inhibited lysozyme levels, but olopatadine, 0.2%, inhibited histamine, albumin, and lysozyme. The effects of olopatadine, 0.1%, were comparable to those of azelastine, 0.1%.

CONCLUSIONS

Olopatadine, at 0.1% and 0.2% concentrations, was effective in suppressing allergen-induced nasal symptoms. At 0.2%, olopatadine provided evidence suggestive of inhibition of mast cell degranulation.

Efficacy of once-daily olopatadine 0.2% ophthalmic solution compared to twice-daily olopatadine 0.1% ophthalmic solution for the treatment of ocular itching induced by conjunctival allergen challenge

Olopatadine 0.1% (Patanol) and olopatadine 0.2% (Pataday) ophthalmic solutions are topical ocular anti-allergic agents with antihistaminic and mast cell stabilizing properties. The efficacy of two doses of olopatadine 0.1% was compared to one dose of olopatadine 0.2% in the prevention of ocular itching associated with allergic conjunctivitis over 24 hours. This double-masked conjunctival allergen challenge (CAC) study found no significant difference in the mean itching scores between two drops of olopatadine 0.1% and one drop of olopatadine 0.2%. Both showed significant activity at the 24-hour time point and were statistically superior to placebo. No adverse events occurred while on drug therapy.

Perception and quality of life associated with the use of olopatadine 0.2% (Pataday) in patients with active allergic conjunctivitis

This 28-d, open-label, multicenter, single-arm clinical study was designed to evaluate perceptions of olopatadine 0.2% in patients with active ocular allergic signs and symptoms. The study enrolled 330 patients, 5 to 94 y of age, who had previously used olopatadine 0.1% for active allergic conjunctivitis. Most patients were white (n=230; 70.1%) and female (n=239; 72.9%). Of all enrolled patients, 328 were evaluable for analysis. Throughout the study, patients instilled 1 drop of olopatadine 0.2% into each eye once daily; adverse events were documented and ocular evaluations were conducted to ensure patient safety. Direct evaluations of efficacy were not performed. On days 1 and 7, patients completed the Rhinoconjunctivitis Quality of Life Questionnaire, recorded their perceptions of olopatadine 0.1% (day 1) or 0.2% (day 7), and had their ocular allergies assessed globally. On each of the first 6 d of treatment, patients also completed a telephone-based perception questionnaire. On day 28, patients returned to the study center, reported their treatment perceptions, had their ocular allergies assessed, and exited the trial. Overall, patients had a positive perception of olopatadine 0.2%. Patients were more satisfied with olopatadine 0.2% than they remembered being with olopatadine 0.1% (289 vs 257 patients; 87.6% vs 77.8%; P<.05). The majority of the 48 patients who wore contact lenses (n=42; 88%) believed that they could wear their contacts as desired. Significant improvement was noted in all categories of the Rhinoconjunctivitis Quality of Life Questionnaire (P<.0001). No unexpected safety findings were reported. Patients perceived olopatadine 0.2% to be effective and well tolerated.

Efficacy and comfort of olopatadine 0.2% versus epinastine 0.05% ophthalmic solution for treating itching and redness induced by conjunctival allergen challenge

BACKGROUND

Olopatadine 0.2% (Pataday, Alcon Laboratories Inc., Fort Worth, Texas, USA) and epinastine 0.05% (Elestat, Inspire Pharmaceuticals, Inc., Durham, NC, USA) are topical ocular anti-allergic agents. Both are H(1) antihistamine/mast cell stabilizers indicated for the treatment of ocular itching associated with allergic conjunctivitis.

OBJECTIVE

To compare the efficacy and comfort of olopatadine 0.2% with epinastine 0.05%, in the prevention of ocular itching associated with allergic conjunctivitis following conjunctival allergen challenge (CAC).

RESEARCH DESIGN AND METHODS

This was a 7 week, four visit, double-masked, randomized, placebo-controlled CAC study. Visit 1 screened subjects for positive ocular allergic responses and Visit 2 confirmed those responses. At Visit 3, 92 subjects were randomized into one of four treatment groups to receive one drop of study medication in each eye: (1) olopatadine 0.2%/placebo, (2) epinastine 0.05%/placebo, (3) olopatadine 0.2%/epinastine 0.05%, (4) placebo/placebo. Subjects were challenged 12 h after drop instillation to evaluate duration of action. At Visit 4, subjects were challenged 5 min after drop instillation to evaluate onset of action. Drop comfort was assessed at Visit 4. MAIN OUTCOME MEASURES;

RESULTS

This article focuses on the results of the onset-of-action challenge (Visit 4). At Visit 4, ocular itching was assessed at 3, 5, and 7 min and redness was assessed at 7, 15, and 20 min post-challenge. Drop comfort was assessed upon instillation, at 30s, and at 1, 2, and 5 min post-instillation. Olopatadine 0.2%-treated eyes exhibited significantly lower mean ocular itching scores versus epinastine 0.05%-treated eyes at 5 (p = 0.024) and 7 min (p = 0.003) post-challenge. Olopatadine 0.2%-treated eyes exhibited significantly lower mean redness scores versus epinastine 0.05%-treated eyes at all time points post-challenge (ciliary: p < or = 0.013, conjunctival: p < or = 0.015, episcleral: p < or = 0.006). Olopatadine 0.2% was rated as significantly more comfortable than epinastine 0.05% at 1 min post-drop instillation (p = 0.003). All adverse events were non-serious and unrelated to study medication. Although the CAC model reproduces allergic responses that are not environmentally-induced, patients experience varying severities of responses as are seen in real-world situations.

CONCLUSION

Olopatadine 0.2% was superior to epinastine 0.05% in preventing ocular itching and redness at onset when induced by the CAC model.

Comparison of the effects of ketotifen fumarate 0.025% and olopatadine HCl 0.1% ophthalmic solutions in seasonal allergic conjunctivities: a 30-day, randomized, double-masked, artificial tear substitute-controlled trial

BACKGROUND

Topical antiallergic agents, such as antihistamines and mast-cell stabilizers, are the main therapeutic options for seasonal allergic conjunctivitis (SAC). Ketotifen fumarate and olopatadine HCl have dual action that offers a combination of these 2 mechanisms. Although clinical studies comparing the efficacy of these 2 drugs have shown that both were effective in the treatment of SAC, the results were contradictory and did not include the effects of these drugs on inflammatory markers.

OBJECTIVES

The aims of this study were to compare the clinical efficacy of topical ketotifen and olopatadine eye drops and to determine the effects of these 2 drugs on the expression of cell adhesion molecules (CAMs) and inflammatory markers in conjunctival surface cells in patients with SAC.

METHODS

This 30-day, randomized, double-masked, artificial tear substitute (ATS)-controlled clinical trial was conducted at the Department of Ophthalmology, Karadeniz Technical University, School of Medicine, Trabzon, Turkey. Patients with SAC were included in the study and randomly assigned to 1 of 3 groups: topical ketotifen fumarate 0.025% ophthalmic solution, topical olopatadine HCl 0.1% ophthalmic solution, or ATS (control group). All drugs were administered 2 drops per eye BID for 30 days. At the beginning of the study (day 0; baseline), on day 15, and on day 30, clinical scores (itching, tearing, redness, eyelid, swelling, and chemosis) and conjunctival impression cytology specimens were obtained. The percentages of cells expressing intercellular adhesion molecule 1, vascular CAM-1, human leukocyte antigen-DR, and beta1-integrin (CD29) from conjunctival impression cytology specimens were determined using flow cytometry. Patients were questioned about adverse events (AEs) at each visit. Ocular discomfort on installation of the drugs was recorded as an AE.

RESULTS

Thirty-nine patients (20 men, 19 women; age range, 18-61 years) with SAC were included. Twelve patients received ketotifen; 13, olopatadine; and 14, ATS. In both active-treatment groups, the improvements of clinical scores (tearing and itching) were more pronounced compared with those in the ATS group, although the day-30 difference in tearing score between the olopatadine and ATS groups was not statistically significant. No significant within-group or between-group differences in mean scores for redness, chemosis, or eyelid swelling were found. The expression rates of CAMs and inflammatory markers in conjunctival surface cells were significantly more reduced with ketotifen and olopatadine compared with ATS. However, clinical and flow cytometric parameters were improved with ATS at 15 and 30 days compared with baseline. No AEs were observed during the study period.

CONCLUSIONS

In this short-term study in a selected, small study population with SAC, ketotifen and olopatadine diminished the expression of CAMs and inflammatory markers on the conjunctival surface cells effectively. Both active treatments were more efficacious compared with ATS and were well tolerated.

Ocular allergy in pediatric practice

Allergies occur frequently in all pediatric age groups, affecting up to 40% of children. Allergic conjunctivitis is the most common ocular allergy syndrome among children, with atopic keratoconjunctivitis and vernal keratoconjunctivitis comprising less common, but potentially more severe, forms of ocular allergy. In this article, we review the impact, diagnosis, potential complications, and treatment of these ocular allergic pediatric conditions. Early detection is necessary to prevent potentially serious consequences of pediatric ocular allergy. Involvement of pediatric ophthalmologists may be necessary to avoid preventable vision loss in severe cases.

Pharmacology of ocular allergy

PURPOSE OF REVIEW

To evaluate the pharmacology of current drug development directed towards ocular allergy. Increased worldwide prevalence of ocular allergy has stimulated expansion of management strategies towards physiologic and immunologic drug targets.

RECENT FINDINGS

Present drug targets are located in the conjunctival mucosal surface at the initial site of allergen exposure. Pharmacologic intervention attends to early and late phase reactions. Targets generating a response include mast cells, IgE, released preformed mediator histamine, and newly formed mediators, such as prostaglandins, leukotrienes and cytokines. Methods to simulate allergy and measure efficacy of drugs are the conjunctival allergen challenge and the conjunctival provocation test. Pharmacologic outcome is measured via cytologic biomarkers and clinical signs/symptoms of redness, itching, lid swelling and chemosis. Endpoint instruments such as the Ocular Allergy Index and Eye Allergy Patient Impact Questionnaire have emerged from the field of pharmacoeconomics.

SUMMARY

Important pharmacologic properties of targets have been revealed. First, histamine is more specifically antagonized by second generation antihistamines. Second, newly formed mediators and downstream responders (prostaglandins, leukotrienes, interleukins, intercellular adhesion molecule 1, tumor necrosis factor, vascular cell adhesion molecule, eosinophils and neutrophils) are more selectively antagonized by dual/multiple-action agents.

Histamine modulates mast cell degranulation through an indirect mechanism in a model IgE-mediated reaction

Histamine is released in inflammatory reactions and exerts an immunoregulatory function on cells present in the microenvironment. In this study, we compared the effect of histamine on degranulation of mast cells derived from animals bearing a parasitic infection with those from uninfected animals. Peritoneal mast cells (PMC) were obtained 24 days after infection of Wistar rats with Toxocara canis. The degree of degranulation was assessed either morphologically or by measuring the release of beta-hexosaminidase and TNF-alpha. Non-purified PMC or mast cells immunomagnetically purified with mAb AA4 were used. An increase in degranulation of non-purified mast cells from infected animals was observed after incubation with histamine in vitro or when histamine was injected into the peritoneal cavity. When a purified mast cell population was used, this effect was no longer observed. Supernatants from spleen cells stimulated with histamine induced degranulation of purified mast cells, and again, this was potentiated with PMC from infected animals. However, when supernatants from peritoneal macrophages similarly stimulated were used, a reduction in the degranulation of PMC from infected animals was observed. Our results suggest that histamine may act as a regulator of mast cell degranulation, thus modulating inflammatory responses due to infection with certain parasites.

Comparative study of topical anti-allergic eye drops on human conjunctiva-derived cells: responses to histamine and IFNγ and toxicological profiles

BACKGROUND

The purpose of the study was to compare toxic effects and responses to histamine and IFN gamma associated with the use of some widely used anti-allergic eye drops commercially available today.

METHODS

For dynamic studies, the Wong-Kilbourne cell line was stimulated for 24 h with histamine or IFN gamma in the presence or absence of anti-allergic eye drops. Supernatants of histamine-stimulated cells were evaluated for the production of IL-6 and IL-8 by ELISA, while the expression of ICAM-1 was evaluated by flow cytometry on IFN gamma-stimulated cells. Toxicological assays were performed using cold light cytofluorometry: viability and apoptosis as well as reactive oxygen species (ROS) and O2(.)- production were assessed using neutral red, Hoechst/propidium iodide, H(2)-DCFDA and hydroethidine tests, respectively.

RESULTS

Antihistamines reduced IL-6 release and presented dose-dependent inhibitory effects on IL-8 production. None of the eye drops decreased the basal or IFN gamma-stimulated expression of ICAM-1. Conversely, eye drops preserved with benzalkonium chloride (BAC) induced even higher ICAM-1 expression levels on IFN gamma-stimulated cells than did IFN gamma alone, whereas unpreserved drugs had no effect. Toxicological assays confirmed the pivotal role of BAC in proportionally reducing cell viability while increasing apoptosis and oxidative stress.

CONCLUSIONS

The ability of topical ocular anti-H(1) drugs to significantly reduce the production of IL-6 and IL-8 argues that they may help treat the inflammatory processes occurring in allergic ocular surface disorders. Nevertheless, preserved ophthalmic formulations may enhance epithelial conjunctival expression of ICAM-1 in the presence of a low inflammatory stimulus, such as IFN gamma, and displayed toxic as well as pro-oxidative effects on these cells. Therefore, BAC used as preservative might in part interfere with the potential anti-inflammatory properties of the active compound by modulating the immuno-inflammatory response of epithelial conjunctival cells.

Emerging drugs for ocular allergy

Ocular allergy is a common condition that usually affects the conjunctiva of the eye and is, therefore, often referred to as allergic conjunctivitis. The severity of the disease can range from mild itching and redness, as seen in seasonal allergic conjunctivitis, to the more severe, sight-threatening forms such as vernal and atopic keratoconjunctivitis. The central mechanism in the pathogenesis of these diseases is IgE-mediated mast cell degranulation and activation of T lymphocytes, eosinophils and conjunctival structural cells. The pharmacotherapy of allergic conjunctivitis consists of several classes of drugs: antihistamines, mast cell stabilisers, dual-acting agents and corticosteroids. None of the available drugs completely abolishes the development of ocular allergy. For this reason, new topical antiallergic/anti-inflammatory agents are currently and continually under clinical trials. This review provides a background to ocular allergic diseases, the medical need for therapy and current and potential new treatments.

Mast cell stabilization and anti-histamine effects of olopatadine ophthalmic solution: a review of pre-clinical and clinical research

BACKGROUND

Histamine receptor activation and degranulation of mast cells are the mechanisms by which the ocular itching, hyperemia, chemosis, eyelid swelling, and tearing of seasonal allergic conjunctivitis are induced. Some of the topical solutions available as anti-allergy therapies are intended to interfere with these mechanisms, and the body of research regarding the capabilities of these therapeutic molecules continues to expand.

OBJECTIVE

To review the currently available literature regarding one topical ophthalmic anti-allergy agent, olopatadine (Patanol), and its anti-histaminic and mast cell stabilizing actions, both in pre-clinical and clinical settings.

DESIGN AND METHODS

Relevant research of laboratory, animal model, and clinical trial studies performed using olopatadine was reviewed. MEDLINE literature searches were conducted and supplemented by additional reports which furthered relevant discussion or were necessary to verify the information resulting from original searches.

RESULTS

Olopatadine demonstrates unique properties both pre-clinically and clinically which differentiate it from other therapeutic molecules in its class of dual action mast cell stabilizer/anti-histamine. Its non-perturbation of cell membranes, human conjunctival mast cell stabilization in vivo and in vitro, and superior efficacy as compared to other topical anti-allergic medications including mast cell stabilizers, anti-histamines, and dual action agents, all contribute to olopatadine's profile.

CONCLUSIONS

Peer-reviewed literature suggests that olopatadine is clinically superior to the other anti-allergic molecules because of its strong anti-histaminic qualities and its unique ocular mast cell stabilizing properties.

A review of the use of olopatadine in allergic conjunctivitis

Ocular allergies are very common and range in intensity from mild, self-resolving, acute conditions to serious, chronic disease that can severely affect vision. The vast majority of sufferers experience relatively mild symptoms, which are often seasonal in nature. Treatments should be simple, comfortable and very safe. They should be able to respond to an ongoing attack but also provide long-term relief from symptoms. Mast cell degranulation is central to all forms of ocular allergic disease and so treatment has concentrated on preventing this process or antagonizing the effects of the primary mediator, histamine. Olopatadine is a relatively new selective H1 antagonist that has mast cell stabilizing properties and has been shown to affect release of TNFalpha and various cytokines from conjunctival epithelial cells. This paper reviews the local ocular use of olopatadine and discusses the place of the drug in the treatment of allergic eye disease.

Effects of a new formulation of olopatadine ophthalmic solution on nasal symptoms relative to placebo in two studies involving subjects with allergic conjunctivitis or rhinoconjunctivitis

BACKGROUND

A new formulation of olopatadine hydrochloride ophthalmic solution (olopatadine 0.2%) was evaluated in two separate, randomized, placebo-controlled, double-masked, hybrid environmental studies intended to determine efficacy and safety in subjects with histories of seasonal allergic conjunctivitis or rhinoconjunctivitis.

DESIGN AND METHODS

In these 10- and 12-week trials (conducted April-August 2003 and July-December 2001, respectively), subjects assessed their ocular signs and symptoms. Additionally, subjects in the 10-week trial evaluated the frequency of their nasal symptoms while subjects in the 12-week trial evaluated both the frequency and severity of their nasal symptoms. The two trials had a combined enrollment of 500 subjects (217 males, 283 females) including 44 children aged 10-17 years; the combined population was 81.4% Caucasian, 9.2% Black, 2% Hispanic, and 7.4% other. Daily throughout these studies, either ragweed (fall study) or grass (spring study) pollen counts were obtained from each investigative center. Slope analyses were conducted on the nasal symptom assessments by pollen count.

RESULTS

The nasal results from the two clinical trials are presented herein. In the fall study, relative to placebo, olopatadine 0.2% significantly reduced the frequency of pollen effects on sneezing (p = 0.0355) and itchy nose (p = 0.0032), and reduced the severity of pollen effects on sneezing (p = 0.0451), itchy nose (p = 0.0178), and runny nose (p = 0.0327). In the spring study, olopatadine 0.2% significantly reduced the frequency of pollen effects on sneezing (p = 0.0017) and runny nose (p = 0.0031) relative to placebo. In the fall trial, 2 subjects discontinued due to treatment-related adverse events (tachycardia and dry eye), while in the spring study, no subject discontinued due to a treatment-related adverse event. No subject in either study suffered a treatment-related serious adverse event.

CONCLUSIONS

For the subjects enrolled in these studies, olopatadine 0.2% appeared to be safe, well-tolerated, and effective in significantly reducing the frequency and/or severity of some effects of pollen on nasal symptoms.

A review of olopatadine for the treatment of ocular allergy

Ocular allergy affects > 20% of the general population and many therapeutic preparations are available to individuals experiencing the most common forms--seasonal and perennial allergic conjunctivitis. 0.1% Olopatadine topical ophthalmic solution is currently approved for the treatment of allergic signs and symptoms in patients > or = 3 years of age. Olopatadine is available in Europe as Opatanol) and in > 30 other countries as Patanol. It inhibits mast cell degranulation and antagonises histamine receptors to manage the itching, redness, chemosis, tearing and lid swelling of the ocular allergic reaction, and its mast cell stabilising ability has been demonstrated both in vitro (using human conjunctival mast cells) and in vivo (human clinical experience). This article reviews both the laboratory and clinical information available on olopatadine, prefaced by a discussion of the current understanding of the ocular allergic reaction and followed by the future implications for this compound. Both laboratory and clinical studies have established the efficacy, safety and comfort of olopatadine in several study design models and comparisons to other antiallergy medications. The application of olopatadine, specifically in the management of lid swelling, an allergic sign recalcitrant to therapy and nasal allergic symptoms has also been established. In the future, a new formulation containing 0.2% olopatadine exhibits a duration of action up to 24 h, supporting once-daily dosing.

Increasing Effect by Simultaneous Use of Levocabastine and Pemirolast on Experimental Allergic Conjunctivitis in Rats

The effect of the simultaneous use of 0.025% levocabastine hydrochloride eye drops (levocabastine) and 0.1% pemirolast potassium ophthalmic solution (pemirolast) on experimental allergic conjunctivitis in rats was investigated. Levocabastine and pemirolast significantly inhibited allergic conjunctivitis compared with the control group when separately administered. In addition, the simultaneous use of both drugs inhibited allergic conjunctivitis more potently than the original activity of levocabastine or pemirolast. Furthermore, the simultaneous use of levocabastine and pemirolast also significantly inhibited increased vascular permeability induced by antigen compared with levocabastine or pemirolast alone, respectively. Levocabastine and pemirolast inhibited histamine release from the rat conjunctiva in correlation with a decrease in histamine content in tears. When levocabastine and pemirolast were simultaneously applied to the eyes, histamine release from the conjunctiva was greater than for the original activities of both drugs. Similar to histamine release from the conjunctiva, the histamine content in tears induced by the simultaneous use of both drugs was significantly decreased compared with levocabastine and pemirolast alone, respectively. A potentiating effect induced by the simultaneous use of levocabastine and pemirolast may be attributable to the antihistaminic activity of levocabastine and histamine release inhibition by levocabastine and pemirolast.

Efficacy and comfort of olopatadine versus ketotifen ophthalmic solutions: a double-masked, environmental study of patient preference

BACKGROUND

Ocular allergies cause itching, redness, chemosis, tearing, and swelling of the eyelids in sensitized individuals. The options available for treatment of ocular allergy include olopatadine 0.1% (Opatanol; Patanol [US]) and ketotifen 0.025% (Zaditen; Zaditor [US]). Patient preference for an eye drop can often be a primary factor in determining the level of compliance and satisfaction with any given therapy.

OBJECTIVE

This study sought patient perspective on eye drop efficacy in controlling signs and symptoms of allergic conjunctivitis and eye drop comfort. Also evaluated were the factors considered by patients when making decisions of preference.

METHODS

One hundred patients with previous history and current symptoms of seasonal or perennial allergic conjunctivitis were enrolled at two centers (Athens, Greece, N = 50; Padova, Italy, N = 50) for this two visit, double-masked study. Qualified patients received two masked bottles of medication (one olopatadine, one ketotifen) and were asked to use both medications as needed over the course of four weeks, but not to exceed usage of two drops of medication per eye per day. At the second visit, patients answered five questions comparing the two masked medications in terms of preference, drop comfort, and efficacy in treatment of signs and symptoms. Patients also defined the factors upon which they based these decisions.

RESULTS

A significantly greater percentage of patients (81%) selected olopatadine when asked which medication they preferred; which they found more comfortable; which they found more efficacious in reducing symptoms of allergy; and which they would select if visiting the doctor's office (P < 0.0001). Seventy-six percent (76%) of patients considered both efficacy and comfort when making their preference decisions (P < 0.0001). No adverse events were volunteered or elicited.

CONCLUSION

In this study, patients preferred to use the anti-allergy eye drop olopatadine over ketotifen after using both drops and evaluating relative efficacy and comfort during the course of four weeks. A significantly greater percentage of the patients preferred to use olopatadine during the study period, found it more efficacious and comfortable, and would select olopatadine if visiting their doctor's office during allergy season.

Clinical efficacy of olopatadine hydrochloride ophthalmic solution 0.2% compared with placebo in patients with allergic conjunctivitis or rhinoconjunctivitis: a randomized, double-masked environmental study

BACKGROUND

Previous studies have suggested that olopatadine hydrochloride ophthalmic solution 0.2% administered once daily is effective for up to 24 hours after instillation and is well tolerated in adults and children aged > or =3 years.

OBJECTIVE

The goal of this study was to evaluate the efficacy and safety profile of olopatadine 0.2% compared with placebo in patients with seasonal allergic conjunctivitis or rhinoconjunctivitis.

METHODS

This was a 10-week, randomized, placebo-controlled, double-masked environmental study conducted during the spring allergy season (April-August) of 2003. Patients assessed their ocular signs and symptoms in terms of frequency (whole-unit scale from 0 to 5) and severity (half-unit scale from 0 to 4), and grass pollen counts were obtained daily for each investigative site. Responder analyses were conducted by pollen level (frequency based) and pollen period (severity based) to evaluate the clinical significance of differences in ocular itching and redness between treatment groups.

RESULTS

Two hundred sixty patients (137 females, 123 males) were enrolled in the study, including 28 children aged between 11 and 17 years; the overall population was 74% white, 11% black, 4% Hispanic, and 11% other. The frequency-based responder analyses of ocular itching and redness showed that when grass pollen counts were high (>20 gr/m(3) air), a respective 21% and 14% of patients in the olopatadine 0.2% group assessed the frequency of ocular itching and redness as >2, compared with 47% and 31% of patients in the placebo group (P < 0.001 for ocular itching; P < 0.003 for redness). The results of the severity-based responder analyses by peak pollen period were consistent with those of the frequency-based analyses. Compared with placebo, olopatadine 0.2% was associated with significant reductions in calculated mean scores for ocular itching and redness by pollen level and by pollen period. No patient was discontinued from the study because of a treatment-related adverse event, and no patient experienced a treatment-related serious adverse event.

CONCLUSION

In the patients studied, olopatadine 0.2% appeared to be effective and well tolerated when administered once daily for the treatment of the ocular signs and symptoms of allergic conjunctivitis or rhinoconjunctivitis.

Interactions of olopatadine and selected antihistamines with model and natural membranes

OBJECTIVE

Olopatadine, an effective topical ocular human conjunctival mast cell stabilizer/antihistaminic antiallergic drug, was evaluated and compared to selected classical antihistamines for their interaction with model and natural membranes to ascertain potential functional consequences of such interactions.

METHODS

The model membranes examined consisted of the argon-buffer interface and monomolecular films of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) at the argon-buffer interface. Interactions with the model membranes were detected as changes in surface tension, i.e., surface pressure. Functional consequences of these interactions were assessed with natural membranes by 6-carboxyfluorescein leakage, hemoglobin release, lactate dehydrogenase release, and histamine release from appropriate cell types.

RESULTS

Measurements at the argon-buffer interface revealed intrinsic surface activity for all agents that ranged from highly surface-active to weakly surface-active in the order of: desloratadine > clemastine > azelastine congruent with ketotifen > diphenhydramine> pyrilamine > emedastine > epinastine > or = olopatadine. This order of amphipathic behavior was confirmed for most of the compounds by estimates of their dissociation constants (K(d,L)) determined from interactions with SOPC monolayers adjusted to a surface pressure approximating that of natural membranes. Epinastine was the only antihistamine that showed a disproportionately greater increase in surface activity toward SOPC in monolayer when compared to other antihistamines. Dissociation constants could not be established for olopatadine because of its low affinity for both the argon-buffer interface and the SOPC monolayer. Functional consequences of these interactions were assessed with natural membranes by 6-carboxyfluorescein leakage (erythrocyte ghosts), hemoglobin release (erythrocytes), lactate dehydrogenase release (conjunctival mast cells, corneal epithelial cells), and histamine release (conjunctival mast cells). Aside from olopatadine and emedastine, all antihistamines promoted a concentration-dependent leakage of hemoglobin from intact erythrocytes. The concentration of drug required to cause half-maximal hemoglobin release (H(50)) from erythrocytes correlated linearly (r = 0.98) with the SOPC dissociation constants (K( d,L)) estimated for the different antihistaminic agents interacting with SOPC monolayers. A similarly high correlation (r = 0.85) emerged from a plot with a slope approaching unity that related drug concentrations required for half-maximal hemoglobin leakage from erythrocytes to threshold doses of drug that caused histamine release from human conjunctival mast cells. Olopatadine was the only agent that did not promote membrane perturbation as monitored by either hemoglobin release from intact erythrocytes, LDH release from human conjunctival mast cells, or 6-carboxyfluorescein release from erythrocyte ghosts. Assessment of the lytic potential of marketed concentrations of ketotifen (0.025%), azelastine (0.05%), and epinastine (0.05%) revealed significant membrane perturbation of human conjunctival mast cells and, importantly, human corneal epithelial cells as indexed by LDH release. This was in contrast to marketed concentrations of olopatadine (0.1%) which maintained normal mast cell and corneal epithelial cell membrane function.

CONCLUSIONS

Combined, these results support the notion that the disruption of natural cell membranes by surface-active antihistamines occurs not through a receptor-mediated process, but is the consequence of a direct interaction of these agents with the cell membrane. This is corroborated by surface pressure-concentration isotherms for adsorption of five different antihistaminic agents to SOPC monolayers where 50% lysis occurred at a surface pressure of 42.9 +/- 1.1 mN/m. Olopatadine appears to be unique among the agents tested by demonstrating low intrinsic surface activity, thus limiting its interaction with natural membranes. At concentrations of about half-maximal compound solubility (, 5.0 mM or a 0.19% drug solution), olopatadine generated SOPC monolayer surface pressures (i.e., 39.82 +/- 0.10 mN/m) that were below those that promoted membrane perturbation and onset of hemoglobin leakage. Olopatadine's restricted interaction with membrane phospholipids limits the degree of membrane perturbation and release of intracellular constituents, including histamine, LDH, and hemoglobin, which is believed to contribute to olopatadine's topical ocular comfort and patient acceptance.

Randomized, double-masked comparison of olopatadine ophthalmic solution, mometasone furoate monohydrate nasal spray, and fexofenadine hydrochloride tablets using the conjunctival and nasal allergen challenge models

BACKGROUND

It is presumed that exposure to allergens in the environment occurs through both the eyes and the nose. Allergic rhinoconjunctivitis is typically treated with a nasal spray or systemic antihistamine, neither of which may provide adequate relief of the ocular component of the disease.

OBJECTIVE

This study was designed to gain a better understanding of the physiologic interaction between the conjunctival and nasal mucosa and thus help establish a profile for the most effective ocular treatment in patients whose allergies have both an ocular and a nasal component.

METHODS

This was a single-center, randomized, double-masked clinical study using the conjunctival allergen challenge (CAC) and nasal allergen challenge (NAC) models. It compared the clinical signs and symptoms induced by CAC and NAC, the effects of drugs administered by 3 different routes, and the movement of fluorescein after instillation into the eye and nose (Jones test), and assessed levels of of inflammatory mediators in tears and nasal secretions. At visit l, subjects previously identified as CAC responders underwent NAC to determine the dose of allergen necessary to elicit a sufficient positive reaction. At visit 2, which took place 1 week later, subjects with a positive reaction at visit 1 were randomized to group A (CAC) or group B (NAC), and underwent challenge to confirm the allergen dose necessary to produce a positive reaction. Subjects who qualified were randomized to receive 1 of 3 treatments: olopatadine 0.1% ophthalmic solution, placebo nasal spray, and placebo tablets; mometasone furoate monohydrate 50-microg nasal spray, placebo topical solution, and placebo tablets; or fexofenadine hydrochloride 180-mg tablets, placebo topical solution, and placebo nasal spray. All study medications were administered according to their approved labeling: drops were administered twice daily in the eyes, and the nasal sprays and tablets were administered once daily. At visit 3, which took place 1 week after visit 2, subjects received study medication and 15 minutes later underwent CAC or NAC as before. The primary efficacy variables were ocular itching, ocular redness, and overall nasal symptoms (sneezing, rhino rrhea/postnasal drip, nasal pruritus, palatal pruritus, and nasal congestion) rated on standard scales. Peak nasal inspiratory flow (PNIF) was measured at each visit, and the Jones test was performed at visits 1 and 3. At baseline and after challenge at visits 2 and 3, tear and nasal lavage samples were collected from a subset of randomly selected subjects for analysis of eosinophil cationic protein and tryptase.

RESULTS

Seventy-three subjects (42 women, 31 men; mean age, 45.26 years [range, 21-73 years]) were screened, and all were randomized to treatment. Two subjects did not complete the study. CAC induced clinically significant (>1 unit difference) ocular and nasal signs and symptoms, whereas NAC induced clinically significant nasal signs and symptoms only. In group A, there was a greater reduction in ocular itching with olopatadine compared with mometasone and fexofenadine at 3 minutes (P = 0.003 and P = 0.008, respectively) and 5 minutes (P = 0.007 and P = 0.013) after challenge. Although the difference was not statistically significant, overall relief of conjunctival redness (average of 3 vessel beds) was greatest in the olopatadine group, followed by fexofenadine. In group B, prevention of total nasal symptoms was significantly greater with mometasone compared with fexofenadine at 20 minutes (P = 0.006) and 30 minutes (P = 0.014) after challenge. There were no statistically significant differences between treatment groups in nasal symptom scores at any time point after CAC. There were also no significant differences in PNIF between treatment groups. Fluorescein was present in nasal secretions within 5 minutes of being instilled into the eye; no fluorescein was detected in the eye after instillation into the nose.

CONCLUSIONS

In this study, exposure of the nasal mucosa to allergen resulted in allergic rhinitis, and exposure of the ocular the ocular surface to allergen resulted in conjunctivitis with a secondary effect in the nose. These results suggest movement of allergens, their mediators, and antiallergy drugs from the ocular surfaces into the nasal cavity, with no meaningful movement from the nasal cavity to the ocular surface. In this controlled model, both the systemic agent and the nasal spray failed to control ocular symptoms. The topical ophthalmic solution provided the most effective management of allergic ocular signs and symptoms, and the nasal spray was most effective for nasal symptoms. Combined use of a nasal spray and topical ophthalmic solution may provide maximal relief in patients whose allergies have both ocular and nasal components.

In vitro inhibition of human conjunctival mast-cell degranulation by ketotifen

Ketotifen relieves the symptoms of allergic conjunctivitis through multiple mechanisms of action. One such mechanism may involve stabilization of conjunctival mast cells. Because of inter- and intra-species variation, however, this hypothesis cannot be adequately tested using mast cells from animals or other human tissues. We therefore employed human conjunctival mast cells. The mast cells were prepared using human conjunctival tissues obtained from US eye banks. Cell suspensions were sensitized with human IgE and incubated with ketotifen fumarate or control. After antigenic challenge of sensitized cells with anti-IgE, levels of histamine and tryptase, two mast-cell granule markers, were measured in the supernatant fluid. Cell viability was assessed with a Trypan Blue assay. Ketotifen at concentrations of approximately 10(-11) to 10(-4) M inhibited mast-cell histamine release by 90% or more. Similarly, ketotifen at approximately 10(-10) to 10(-4) M inhibited tryptase release by 90% or more (apart from a single anomalous reading). At all ketotifen concentrations that stabilized mast cells, cell viability was preserved. Moreover, ketotifen did not impair cell viability unless concentrations were increased above the clinically relevant range, i.e., above the order of magnitude of 10(-4) M. These data demonstrate that ketotifen can stabilize human conjunctival mast cells, without impairing cell viability.

Topical immunopharmacology of ocular allergies

PURPOSE OF REVIEW

To review the histamine-1 receptor antagonists, mast cell blockers and natural agents with such actions that can be used for the topical treatment of ocular allergies.

RECENT FINDINGS

Increasing evidence indicates that some histamine-1 receptor antagonists have additional actions to inhibit secretion of inflammatory mediators, especially cytokines, from ocular mast cells and other cell types. Emerging information suggests that such actions may be through regulation of intracellular calcium ion levels of NF-kappaB activation.

SUMMARY

A number of available drugs and natural non-prescription agents may have anti-histaminic and anti-inflammatory actions.