Randomized, double-masked, placebo-controlled comparison of the efficacy of emedastine difumarate 0.05% ophthalmic solution and ketotifen fumarate 0.025% ophthalmic solution in the human conjunctival allergen challenge model

Therapeutic Targets in Allergic Conjunctivitis

Allergic conjunctivitis (AC) is a common condition resulting from exposure to allergens such as pollen, animal dander, or mold. It is typically mediated by allergen-induced crosslinking of immunoglobulin E attached to receptors on primed conjunctival mast cells, which results in mast cell degranulation and histamine release, as well as the release of lipid mediators, cytokines, and chemokines. The clinical result is conjunctival hyperemia, tearing, intense itching, and chemosis. Refractory and chronic cases can result in ocular surface complications that may be vision threatening. Patients who experience even mild forms of this disease report an impact on their quality of life. Current treatment options range from non-pharmacologic therapies to ocular and systemic options. However, to adequately control AC, the use of multiple agents is often required. As such, a precise understanding of the immune mechanisms responsible for this ocular surface inflammation is needed to support ongoing research for potential therapeutic targets such as chemokine receptors, cytokine receptors, non-receptor tyrosine kinases, and integrins. This review utilized several published articles regarding the current therapeutic options to treat AC, as well as the pathological and immune mechanisms relevant to AC. This review will also focus on cellular and molecular targets in AC, with particular emphasis on potential therapeutic agents that can attenuate the pathology and immune mechanisms driven by cells, receptors, and molecules that participate in the immunopathogenesis and immunopathology of AC.

The Effect Of Topical Antihistamines Used Single Dose Daily in Allergic Conjunctivitis

Background and Objective:

To evaluate the efficacy of 0.2% olopatadine and to compare olopatadine 0.1%, ketotifen 0.025% and emadastine 0.05% in the treatment of allergic conjunctivitis.

Methods:

In this retrospectively designed study, we investigated the files of patients who had been diagnosed with perineal or seasonal allergic conjunctivitis in the teaching hospital of Maltepe University between April 2017 and July 2017. We divided the patients into four groups. The patients in each group had similar symptoms and scores before medication. The first, second, third and fourth groups were prescribed olapatadine 0.1%, olopatadine 0.2%, ketotifen 0.025% and emedastine 0.05%, respectively. We evaluated the symptoms and signs of the patients on the 15th day after treatment, and compared the results between the groups.

Results:

We investigated the files of 80 patients. There were 20 patients in each group. We evaluated the symptoms and finding scores after treatment. The symptoms and findings of allergic conjunctivitis had improved in all the four groups. There was no difference in the treatment responses between the four groups.

Conclusion:

Olopatadine 0.2%, olopatadine 0.1%, ketotifen 0.025% and emedastine 0.05% were all equally effective in improving the signs and symptoms of allergic conjunctivitis.

Efficacy and Tolerability of Ketotifen in the Treatment Of Seasonal Allergic Conjunctivitis: Comparison between Ketotifen 0.025% and 0.05% Eye Drops

Purpose: To study the tolerability and efficacy of two formulations of topical ketotifen ophthalmic solutions for the treatment of seasonal allergic conjunctivitis (SAC).Methods: 81 active SAC patients were treated with either ketotifen 0.025% or 0.05% eye drops for 3 weeks. Allergic signs and symptoms were evaluated at baseline (V0), after 7 (V1) and 21 days (V2). Drugs tolerability and ratings of global efficacy were recorded.Results: Both concentrations of ketotifen were highly effective. The total signs and symptoms scores (TSSS) were significantly better reduced by ketotifen 0.025% compared to 0.05% at both V1 and V2 (p < 0.001). Ketotifen 0.025% was better tolerated than 0.05% at the first instillation and at days 2, 4, and 6 (p < 0.0001), and had a better responder rate (p < 0.001) according to the patient's and investigator's assessments.Conclusions: Ketotifen 0.025% was more effective and better tolerated than 0.05% in SAC.

Bepotastine besilate ophthalmic solution 1.5% for alleviating nasal symptoms in patients with allergic conjunctivitis

Background

Bepotastine besilate ophthalmic solution (BBOS) 1.5% is a topical antihistamine for the treatment of ocular itching associated with allergic conjunctivitis (AC). Allergic rhinitis and AC are common comorbid conditions. We explored the efficacy of BBOS 1.5% in alleviating nasal symptoms in an integrated analysis of two Phase III conjunctival allergen challenge (CAC) studies and a Phase IV environmental allergen study.

Methods

In the Phase III trials, a CAC was performed 15 minutes, 8 hours, and 16 hours following ocular instillation of BBOS 1.5% (n=78) or placebo (n=79), and subjects evaluated nasal symptoms. In the environmental study, subjects instilled BBOS 1.5% (n=123) or placebo (n=122) twice daily and nasal symptoms were evaluated over 2 weeks.

Results

In the Phase III trials, BBOS 1.5% had reduced CAC-induced nasal congestion and pruritus at 15 minutes and 8 hours postdosing and rhinorrhea and a non-ocular composite-symptom score (sum of nasal scores plus ear or palate pruritus) at all time points postdosing (all P≤0.01 vs placebo). In the Phase IV environmental study, BBOS 1.5% reduced sneezing and nasal pruritus over 2 weeks and median number of days to improvement of nasal pruritus and total nasal symptom score (sum for rhinorrhea, sneezing, nasal pruritus, and nasal congestion; P≤0.04 vs placebo). Additionally, investigator-reported improvement in overall ocular (pruritus, hyperemia, tearing) and nasal symptoms was greater with BBOS 1.5% vs placebo (P≤0.03).

Conclusion

Results of these exploratory analyses indicate that topical ocular BBOS 1.5% reduced nasal symptoms, supporting its use for alleviating rhinitis symptoms associated with AC.

Antihistamines and itch

Histamine is one of the best-characterized pruritogens in humans. It is known to play a role in pruritus associated with urticaria as well as ocular and nasal allergic reactions. Histamine mediates its effect via four receptors. Antihistamines that block the activation of the histamine H₁receptor, H₁R, have been shown to be effective therapeutics for the treatment of pruritus associated with urticaria, allergic rhinitis, and allergic conjunctivitis. However, their efficacy in other pruritic diseases such as atopic dermatitis and psoriasis is limited. The other histamine receptors may also play a role in pruritus, with the exception of the histamine H₂receptor, H₂R. Preclinical evidence indicates that local antagonism of the histamine H₃receptor, H₃R, can induce scratching perhaps via blocking inhibitory neuronal signals. The histamine H₄receptor, H₄R, has received a significant amount of attention as to its role in mediating pruritic signals. Indeed, it has now been shown that a selective H₄R antagonist can inhibit histamine-induced itch in humans. This clinical result, in conjunction with efficacy in various preclinical pruritus models, points to the therapeutic potential of H₄R antagonists for the treatment of pruritus not controlled by antihistamines that target the H₁R.

A review of non-pharmacological and pharmacological management of seasonal and perennial allergic conjunctivitis

Allergic eye disease encompasses a group of hypersensitivity disorders which primarily affect the conjunctiva and its prevalence is increasing. It is estimated to affect 8% of patients attending optometric practice but is poorly managed and rarely involves ophthalmic assessment. Seasonal allergic conjunctivitis (SAC) is the most common form of allergic eye disease (90%), followed by perennial allergic conjunctivitis (PAC; 5%). Both are type 1 IgE mediated hypersensitivity reactions where mast cells play an important role in pathophysiology. The signs and symptoms are similar but SAC occurs periodically whereas PAC occurs year round. Despite being a relatively mild condition, the effects on the quality of life can be profound and therefore they demand attention. Primary management of SAC and PAC involves avoidance strategies depending on the responsible allergen(s) to prevent the hypersensitivity reaction. Cooled tear supplements and cold compresses may help bring relief. Pharmacological agents may become necessary as it is not possible to completely avoid the allergen(s). There are a wide range of anti-allergic medications available, such as mast cell stabilisers, antihistamines and dual-action agents. Severe cases refractory to conventional treatment require anti-inflammatories, immunomodulators or immunotherapy. Additional qualifications are required to gain access to these medications, but entry-level optometrists must offer advice and supportive therapy. Based on current evidence, the efficacy of anti-allergic medications appears equivocal so prescribing should relate to patient preference, dosing and cost. More studies with standardised methodologies are necessary elicit the most effective anti-allergic medications but those with dual-actions are likely to be first line agents.

Emedastine difumarate: a review of its potential ameliorating effect for tissue remodeling in allergic diseases

BACKGROUND

Emedastine difumarate, a selective histamine-H1 receptor antagonist and effective antiallergic agent, inhibits various clinical symptoms of allergic rhinitis, allergic conjunctivitis, urticaria, allergic dermatitis, pruritus cutaneous, and prurigo. In addition to greater efficacy than other antihistamines, emedastine difumarate produces no adverse cardiovascular effects and exhibits minimal anticholinergic activity. Moreover, a recent study revealed that the effect of emedastine difumarate on inhibition of histamine-induced collagen synthesis in vitro was greater in dermal fibroblasts than in nasal mucosa fibroblasts. This result indicates that there are tissue-specific effects of emedastine difumarate and that it may be more effective for treating fibrosis in skin than in nasal mucosa. However, the mechanism and role of tissue remodeling is less well established for allergic skin diseases and allergic conjunctivitis, in comparison to respiratory allergic diseases.

OBJECTIVE

This review outlines the involvement of histamine in the pathogenesis of tissue remodeling in a variety of organs, and presents the evidence for the effect of antihistamines on this process. Furthermore, this review also discusses antihistamines as an intervention strategy in tissue remodeling.

METHODS

The scientific literature, published abstracts, and selected textbooks were reviewed.

RESULTS/CONCLUSION

Although additional evidence is required, emerging evidence suggests that emedastine difumarate may be of value in the prevention of excess tissue remodeling in allergic skin inflammation.

Efficacy of olopatadine HCI 0.1%, ketotifen fumarate 0.025%, epinastine HCI 0.05%, emedastine 0.05% and fluorometholone acetate 0.1% ophthalmic solutions for seasonal allergic conjunctivitis: a placebo-controlled environmental trial

PURPOSE

We aimed to compare the clinical efficacy and ocular surface variables of olopatadine, ketotifen fumarate, epinastine, emedastine and fluorometholone acetate ophthalmic solutions in preventing the signs and symptoms of seasonal allergic conjunctivitis (SAC).

METHODS

This was a prospective, randomized, double-blinded and placebo-controlled study. A total of 100 patients with SAC were randomly assigned to one of five groups, in which they were administered olopatadine, ketotifen fumarate, epinastine, emedastine or fluorometholone acetate, instilled twice daily for 2 weeks. One eye of each patient was treated with the study drug and the other was treated with a placebo. Signs and symptoms of allergic conjunctivitis (itching, redness, tearing, chemosis and eyelid swelling) were scored on a 4-point scale. Each symptom was assessed at baseline and then again after 1 and 2 weeks of treatment. Ocular surface variables were assessed by conjunctival impression cytology.

RESULTS

At weeks 1 and 2, all antiallergic agents were significantly more effective than placebo in alleviating itching, redness, tearing, chemosis and eyelid swelling. Fluorometholone acetate was significantly less effective than the other agents in reducing itching and redness at all control visits. Ocular surface findings by impression cytology improved significantly after all treatments compared with placebo.

CONCLUSIONS

In patients with SAC, olopatadine, ketotifen, epinastine and emedastine are more efficacious than fluorometholone acetate in preventing itching and redness. All the antiallergic agents gave similar results in terms of reducing tearing, chemosis and eyelid swelling. Our data showed that impression cytology parameters improved after treatment with antiallergic agents in patients with SAC.

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.

A comparison of the clinical efficacy of pheniramine maleate/naphazoline hydrochloride ophthalmic solution and olopatadine hydrochloride ophthalmic solution in the conjunctival allergen challenge model

BACKGROUND

The signs and symptoms of allergic conjunctivitis include ocular redness and itching. Two treatment options currently indicated for acute ocular allergic reaction are pheniramine maleate 0.3%/naphazoline hydrochloride 0.025% ophthalmic solution, an over-the-counter antihistamine/vasoconstrictor combination; and olopatadine hydrochloride 0.1% ophthalmic solution, a prescription antihistamine/mast cell stabilizer.

OBJECTIVE

This study was designed to compare, at onset of action, the relative effectiveness of pheniramine/naphazoline and olopatadine, when administered before conjunctival allergen challenge (CAC), using the ocular allergy index (OAI) as the primary end point.

METHODS

This was a prospective, randomized, double-masked, contralateral, active- and placebo-controlled, single-center study of the CAC model. The first 2 study visits established and confirmed the subjects' ocular allergic reaction (no medication administered). At visit 3, the subjects were randomly assigned to 1 of 3 contralateral (right eye vs left eye) treatment combinations: pheniramine/naphazoline + olopatadine, pheniramine/naphazoline + placebo, or olopatadine + placebo. Medication was given 10 minutes before CAC. The subjects' erythema in the ciliary, conjunctival, and episcleral vessel beds; eyelid swelling; chemosis; and itching were evaluated at 7, 12, and 20 minutes after CAC. The OAI was calculated as a composite score of 6 signs and symptoms of allergic conjunctivitis to assess global severity. Between-treatment differences in OAI scores were used to evaluate efficacy. Subjects were asked their eye drop preference at the conclusion of visit 3.

RESULTS

Subjects (n = 83) ranged in age from 20 to 70 years (mean, 42.5 years), 61.4% (n = 51) were female, and 94.0% (n = 78) were white. Both pheniramine/naphazoline and olopatadine were associated with significantly lower OAI scores than placebo at all 3 time points (all, P < 0.001). OAI scores were significantly lower with pheniramine/naphazoline than with olopatadine at 12 and 20 minutes (P = 0.005 and P = 0.001, respectively).

CONCLUSION

In this patient sample, studied in a CAC model of onset of action, prophylactic pheniramine/naphazoline was more effective than olopatadine and placebo in alleviating the signs and symptoms of the acute ocular allergic reaction, as measured by the OAI.

Efficacy and safety of ketotifen fumarate 0.025% in the conjunctival antigen challenge model of ocular allergic conjunctivitis

PURPOSE

To determine the duration of action of ketotifen 0.025% eye drops vs placebo taken as single or multiple doses in an allergen challenge model.

DESIGN

Two randomized, multicenter, double-masked, contralateral placebo-controlled studies, one a single-dose and one a multiple-dose study.

METHODS

Two conjunctival provocation tests (CPTs) were initially conducted to confirm reproducibility of subject responses in both studies. Subjects in study 1 (n = 87) received single doses of ketotifen in one eye and placebo in the other 15 minutes, 6 hours, and 8 hours before CPT. Subjects in study 2 (n = 85) received ketotifen or placebo once 8 hours before CPT. Single-dose efficacy results were used to further qualify a subject as a responder. Responders were re-randomized to a 4-week twice daily dosing regimen with a CPT 8 hours after the final dose. In both studies, ocular symptoms were assessed at three time points 3 to 15 minutes after challenge. There were no significant differences in adverse events between groups.

RESULTS

For both studies, ocular itching and vascular injection were significantly reduced (P <.003) at all time points after instillation of ketotifen, with a maximum reduction at 7 minutes postchallenge. In study 2, chemosis, tearing, and lid swelling were also assessed and were significantly reduced (P <.008) after instillation of ketotifen.

CONCLUSIONS

Ketotifen 0.025% eye drops were safe and statistically effective in preventing ocular itching, injection, and other signs and symptoms of allergic conjunctivitis at 15 minutes, 6 hours, and 8 hours after a single dose and at 8 hours after the final dose of a 4-week twice daily regimen.

Conjunctival allergen challenge: models in the investigation of ocular allergy

Recently, the number of agents to treat ocular allergy has increased dramatically, from three (pheniramine, antazoline, cromolyn) to more than a dozen. A general increase in the incidence of atopy in recent years and the fact that patients are becoming less tolerant of bothersome signs and symptoms have been driving forces in this increase. As visual tasking, such as reading and working on a computer, has become more prevalent, there is an increased awareness of ocular allergy and the impact it has on quality of life and productivity at work and school. With the need for more effective medications, the development of models, such as the conjunctival allergen challenge (CAC), has made the identification of new agents more efficient. In this article, we review the relevant background on the science behind allergen challenges in the eye, how models are designed, and how models are used in the field today.

The anti-allergic effects of a cromolyn sodium-chlorpheniramine combination compared to ketotifen in the conjunctival allergen challenge model

PURPOSE

To compare the inhibitory effects of a topical combination product, cromolyn sodium (DSCG) 4% with the antihistamine, chlorpheniramine, with those of topical ketotifen 0.05% on the clinical allergic reaction induced by the conjunctival allergen challenge (CAC).

METHODS

Ten allergic but non-active patients were challenged in both eyes with increasing doses of specific allergen to obtain a positive bilateral reaction (visit 1). They were then rechallenged after 1 week to confirm the allergic threshold dose response (visit 2). After 2 weeks, a third CAC was performed bilaterally 30 minutes after topical application of DSCG-chlorpheniramine in one eye and ketotifen in the contralateral eye in a double-masked fashion (visit 3). Clinical signs and symptoms were registered 5, 10, 15, and 20 minutes after challenge using the standard scoring system. Tear cytology was performed 30 minutes after challenge.

RESULTS

Comparing the two drug effects at visit 3, DSCG-chlorpheniramine was shown to be superior to ketotifen at all time points for itching (p < 0.01) and at 5 minutes for redness (p < 0.01). For the total signs score, DSCG-chlorpheniramine was shown to be superior to ketotifen at all time points (p < 0.01), and at 10 and 15 minutes for the total symptoms score (p < 0.05). Compared to visit 2, DSCG-chlorpheniramine significantly lowered itching (p < 0.001) and redness (p < 0.05) at 5, 10, 15, and 20 minutes after challenge. Ketotifen significantly lowered itching at 5 and 10 minutes (p < 0.001) and redness at 5, 10, and 15 minutes (p < 0.05). Both drugs reduced the total number of cells evaluated by tear cytology during the early-phase reaction (p < 0.05).

CONCLUSIONS

DSCG-chlorpheniramine was found to be more effective than ketotifen at preventing itching and redness in the CAC model.

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.

Onset and Duration of Action of Ketotifen???0.025%???and???Emedastine???0.05% in Seasonal Allergic Conjunctivitis

OBJECTIVE

To compare the efficacy, onset and duration of action, and the safety of ketotifen fumarate 0.025% ophthalmic solution and emedastine difumarate 0.05% ophthalmic solution in subjects with seasonal allergic conjunctivitis (SAC) induced by allergen exposure, using the Vienna Challenge Chamber model.

DESIGN AND SETTING

This was a double-masked, randomised, comparative, crossover study conducted at an allergy outpatient clinic in Austria.

STUDY PARTICIPANTS

Subjects with an allergy to grass pollen were exposed to the allergen in a pollen chamber for 4 hours, followed by a 3-hour break and then a second exposure for 3 hours.

INTERVENTIONS

Study participants were randomised to a treatment sequence (ketotifen followed by emedastine or emedastine followed by ketotifen), receiving 1 drop per eye of ketotifen or emedastine 2 hours after the initial allergen exposure in the pollen chamber.

OUTCOMES

Individual and composite ocular, individual and composite nasal, and total (ocular + nasal) symptom complex scores were determined by repeated exposure to allergen 0-2 hours and 5-8 hours after dosing. Onset of action was defined as the time to the first observation of a 20% reduction from baseline in the composite ocular symptom score.

RESULTS

All 37 subjects enrolled completed the study. The median time to onset of action was 15 minutes for ketotifen and 30 minutes for emedastine. This difference was significant using the generalised linear model (p = 0.048), but not for the log-rank test analysis. In the initial 2 hours post dose, ketotifen provided significantly greater relief of both composite ocular symptoms (p = 0.026) and total symptom complex (p = 0.014). Both medications were effective in reducing symptoms 5 to 8 hours after dosing. No adverse events were reported for either treatment.

CONCLUSIONS

In the Vienna Challenge Chamber model, ketotifen and emedastine both effectively alleviated ocular symptoms of SAC after single-dose administration. Ketotifen had a faster onset of action and provided better symptom relief than emedastine during the first 2 hours after dosing. The rapid onset of action and symptom control make ketotifen a valuable treatment for SAC.