Clinical efficacy of olopatadine vs epinastine ophthalmic solution in the conjunctival allergen challenge model

Emerging Therapeutics for Ocular Surface Disease

PURPOSE OF REVIEW

The purpose of this article is to review treatment advances in ocular allergy that include the treatment of the various signs and symptoms of the allergic inflammatory response of the ocular surface.

RECENT FINDINGS

Recent studies have demonstrated improved pharmacological effect of topical agents with artificial tears and cold compresses; brimonidine, a new ophthalmic decongestant which has demonstrated decreased rebound conjunctivitis; and potential use of contact lens and other novel delivery instruments to increase medication retention time. Currently, there have been limited advances in novel ophthalmic treatments. Non-pharmacological interventions have demonstrated in a randomized control study that artificial tears and the use cold compresses alone or in combination with ophthalmic antihistamines can enhance the effectiveness of a traditional pharmacological therapy. The primary advances have been the start of head-to-head studies comparing various agents actively being used in the treatment of ocular allergy. In addition, there has been increasing interest in the development of novel delivery systems to increase residence time of pharmacological agents in the ocular surface such as nanoparticles, microfilms; examining novel pathways of controlling the allergic inflammatory response of the ocular surface such as modulation of cytokines, transcription factors, and immunophilins.

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.

Olopatadine hydrochloride ophthalmic solution for the treatment of allergic conjunctivitis

INTRODUCTION

Olopatadine hydrochloride is an antihistamine and mast cell stabilizer available as oral, intranasal and ocular preparations. Most of the practical applications of olopatadine therapy focus on the treatment of allergic rhinoconjunctivitis via intranasal and ocular routes. Areas covered: This article was created from a comprehensive literature search with information taken from meta-analyses, systematic reviews, and clinical trials of children and adults. The articles that have been selected, evaluate the use of intranasal and ocular antihistamines and their role in allergic rhinoconjunctivitis. Expert opinion: Olopatadine is significantly more effective than placebos in relieving the symptoms of allergic rhinoconjunctivitis. It can function both as a viable alternative or addition to first line therapies such as intranasal steroids and oral antihistamines.

Topical Olopatadine in the Treatment of Allergic Conjunctivitis: A Systematic Review and Meta-analysis

PURPOSE

To assess the safety and efficacy of topical olopatadine versus placebo and other topical anti-allergic medications in treating allergic conjunctivitis.

METHODS

We systematically searched the literature for randomized-controlled trials that included patients with allergic conjunctivitis, compared olopatadine versus placebo or alternative anti-allergic medications, and examined itch, conjunctival hyperemia, composite symptom or sign scores, and/or occurrence of adverse events. We assessed the safety and efficacy of topical olopatadine when compared with placebo or alternative anti-allergic medications using meta-analysis.

RESULTS

When compared with placebo, topical olopatadine is associated with a pooled-mean difference (MD) in ocular itch of -1.33 (p < 0.00001) and ocular hyperemia of -0.92 (p < 0.00001). When compared with other agents, olopatadine was inferior to alcaftadine on ocular itch (pooled-MD = 0.39; p < 0.00001) but comparable with epinastine and ketotifen.

CONCLUSIONS

Topical olopatadine is a safe and effective treatment modality for allergic conjunctivitis, whereas alcaftadine appears to be superior to olopatadine in reducing ocular itch.

Efficacy and safety of olopatadine hydrochloride 0.77% in patients with allergic conjunctivitis using a conjunctival allergen-challenge model

Background

Symptom relief for the duration of 24 hours after treatment would benefit patients with allergic conjunctivitis.

Objective

To compare the safety and efficacy of olopatadine 0.77% with vehicle or olopatadine 0.2% in patients with allergic conjunctivitis in a conjunctival allergen-challenge clinical study.

Patients and methods

In this Phase III, multicenter, double-masked, parallel-group, randomized trial, patients with allergic conjunctivitis received olopatadine 0.77%, its vehicle, or olopatadine 0.2%, administered once at visits 3A (day 0), 4A (day 14 ±2), and 5 (day 21 +3). Allergic conjunctivitis-associated sign and symptom assessments included ocular itching, conjunctival redness, total redness, chemosis, and tearing scores. Adverse events and ocular safety parameters were also assessed.

Results

A total of 202 qualifying patients were randomized. Olopatadine 0.77% was superior (P<0.001) to vehicle for treatment of ocular itching at 3, 5, and 7 minutes postchallenge at onset of action and 16- and 24-hour duration of action. Conjunctival redness mean scores were significantly lower for olopatadine 0.77% versus vehicle at all three post-conjunctival allergen-challenge time points: onset (−1.52 to −1.48; P<0.001), 16 hours (−1.50 to −1.38; P<0.01), and 24 hours (−1.58 to −1.38; P<0.05). At 24 hours, olopatadine 0.77% was superior to olopatadine 0.2% at all three postchallenge time points for ocular itching (P<0.05), conjunctival redness (P<0.05), and total redness (P<0.05). No clinically relevant differences in safety parameters or adverse events were observed between the treatment groups.

Conclusion

Olopatadine 0.77% is superior to both its vehicle and olopatadine 0.2% for the treatment of allergen-mediated ocular itching and conjunctival redness. Ocular itching symptom relief is maintained over 24 hours, supporting once-daily dosing and demonstrating a comparable safety profile to olopatadine 0.2%.

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.

Efficacy of olopatadine versus epinastine for treating allergic conjunctivitis caused by Japanese cedar pollen: a double-blind randomized controlled trial

Introduction

The objective of this study was to compare the efficacy and safety of olopatadine versus epinastine in healthy Japanese adults with a history of allergic conjunctivitis to Japanese cedar pollen.

Methods

This Phase IV double-blind randomized controlled clinical trial comprised three clinical visits over 30 days. Screening tests were performed to identify subjects with a history of allergic conjunctivitis to Japanese cedar pollen in terms of skin sensitivity and positive bilateral reactions to a conjunctival allergen challenge (CAC) with Japanese cedar pollen at Visit 1, and confirmation by a positive bilateral CAC reaction at Visit 2. At Visit 3, the subjects were randomized to receive one drop of olopatadine HCl ophthalmic solution 0.1% (olopatadine) in the left or right eye (1:1 ratio). All subjects received one drop of epinastine HCl ophthalmic solution 0.05% (epinastine) in the contralateral eye as an active control. Five min later, the subjects underwent bilateral CAC tests with one drop of the allergen solution at the concentration that elicited positive reactions at Visits 1 and 2. Efficacy outcomes included the severity of ocular itching at 5, 7, and 15 min and the severity of conjunctival hyperemia at 7, 15, and 20 min after the CAC test, as graded by the investigator by biomicroscopy.

Results

Fifty people participated in this study (25 per group). Olopatadine significantly reduced ocular itching at 7 and 15 min (both p < 0.05) and conjunctival hyperemia at 7 and 20 min (p = 0.0010 and p < 0.05, respectively) after allergen exposure compared with epinastine. There were no adverse events for either treatment.

Conclusion

The results of this single-dose study suggest that olopatadine is superior to epinastine in terms of suppressing ocular itching and hyperemia induced by Japanese cedar pollen during CAC tests. Further studies are needed to confirm these findings in real-life settings.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0156-2) contains supplementary material, which is available to authorized users.

Allergic eye disease

Ocular allergy is one of the most common conditions encountered by pediatricians and ophthalmologists and is characterized by bilateral injection with itching as the predominant symptom. Risk factors include history of atopy (asthma, eczema, seasonal allergies). Basic and clinical research have provided insight into the immunologic mechanisms, clinical presentation, differential diagnosis, and pharmacologicmanagement of this condition. New pharmacologic agents have improved the efficacy and safety of ocularallergy treatment. This article discusses the classification of ocular allergy diagnosis and management, and addresses clinical symptoms and signs that indicate more severe allergic disease or alternative diagnosis that should prompt expeditious referral to an ophthalmologist.

Effectiveness of nonpharmacologic treatments for acute seasonal allergic conjunctivitis

OBJECTIVE

To investigate whether artificial tears and cold compress alone or in combination provide a treatment benefit and whether they were as effective as or could enhance topical antiallergic medication.

DESIGN

Randomized, masked clinical trial.

PARTICIPANTS

Eighteen subjects (mean age, 29.5±11.0 years) allergic to grass pollen.

INTERVENTION

Controlled exposure to grass pollen using an environmental chamber to stimulate an ocular allergic reaction followed by application of artificial tears (ATs), 5 minutes of cold compress (CC), ATs combined with CC, or no treatment applied at each separate visit in random order. A subset of 11 subjects also had epinastine hydrochloride (EH) applied alone and combined with CC in random order or instillation of a volume-matched saline control.

MAIN OUTCOME MEASURES

Bulbar conjunctival hyperemia, ocular surface temperature, and ocular symptoms repeated before and every 10 minutes after treatment for 1 hour.

RESULTS

Bulbar conjunctival hyperemia and ocular symptoms decreased and temperature recovered to baseline faster with nonpharmaceutical treatments compared with no treatment (P <0.05). Artificial tears combined with CC reduced hyperemia more than other treatments (P <0.05). The treatment effect of EH was enhanced by combining it with a CC (P <0.001). Cold compress combined with ATs or EH lowered the antigen-raised ocular surface temperature to less than the pre-exposure baseline. Artificial tear instillation alone or CC combined with ATs or EH significantly reduced the temperature (P <0.05). Cold compress combined with ATs or EH had a similar cooling effect (P >0.05). At all measurement intervals, symptoms were reduced for both EH and EH combined with CC than CC or ATs alone or in combination (P <0.014).

CONCLUSIONS

After controlled exposure to grass pollen, CC and AT treatment showed a therapeutic effect on the signs and symptoms of allergic conjunctivitis. A CC enhanced the use of EH alone and was the only treatment to reduce symptoms to baseline within 1 hour of antigenic challenge. Signs of allergic conjunctivitis generally were reduced most by a combination of a CC in combination with ATs or EH.

Once-daily olopatadine ophthalmic solution 0.2% in the treatment of allergic conjunctivitis and rhinoconjunctivitis

Olopatadine hydrochloride ophthalmic solution 0.2% is a new once-daily formulation of olopatadine that is indicated for the treatment of ocular itching associated with allergic conjunctivitis. This formulation has demonstrated a safety, efficacy and comfort profile similar to that of olopatadine 0.1%. The advantages of once-daily dosing, however, may include cost-effectiveness, improvement in patient compliance and an improvement in quality of life. This review article will summarize literature reports on the 0.2% formulation of olopatadine from the standpoint of efficacy, safety, total treatment costs, therapeutic outcomes, patient compliance and effect on quality of life.

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.

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.

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.

Management of allergic conjunctivitis: an evaluation of the perceived comfort and therapeutic efficacy of olopatadine 0.2% and azelastine 0.05% from two prospective studies

PURPOSE

Results from 2 patient-reported outcome studies of allergic conjunctivitis sufferers who used olopatadine 0.2% and azelastine 0.05% are analyzed.

METHODS

The PACE (Pataday Allergic Conjunctivitis Evaluation) multi-center, prospective, open-label study examined patient perceptions of olopatadine 0.2% once daily (qd) and previous twice daily (bid) allergic conjunctivitis medications via questionnaire in allergic conjunctivitis sufferers who had previously used bid medication and then initiated olopatadine. A second conjunctival antigen challenge (CAC) study evaluated comfort of 4 allergic conjunctivitis medications.

RESULTS

Forty-nine patients from the PACE study (N = 125) with prior azelastine use were examined. Significantly more patients rated themselves "very satisfied" with current olopatadine use compared with past azelastine use on drop comfort (p < 0.0001), speed of relief (p = 0.0004), and overall satisfaction (70% vs 16%, p < 0.0001). Significantly more patients reported olopatadine "very effective" against swelling compared with azelastine (47% vs 8%, p = 0.0404). In the CAC study (N = 36), data from olopatadine (n = 8), azelastine (n = 9) and placebo (N = 36) groups were reported. Olopatadine was rated significantly more comfortable than azelastine upon instillation (p = 0.0223), at 30 seconds (p = 0.0479), and at 1 minute after instillation (p = 0.0240).

CONCLUSION

In the reported studies, olopatadine 0.2% qd was more comfortable than azelastine 0.05% and preferred by patients with allergic conjunctivitis by a ratio of 4:1.

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.

Safety and tolerability of olopatadine 0.2% in children and adolescents

OBJECTIVE

The aim of this study was to evaluate the safety of olopatadine hydrochloride ophthalmic solution 0.2% in children and adolescents 3-17 years of age.

METHODS

In this 6-week, randomized, double-masked safety evaluation, eligible subjects with asymptomatic eyes underwent in-office visits at weeks 1, 3, and 6 and were contacted by telephone at weeks 2, 4, and 5. Qualified subjects were assigned randomly in a 2:1 ratio of olopatadine 0.2% to vehicle (identical formation without the active ingredient) for dosing on a once-daily schedule. Safety parameters assessed included adverse events, visual acuity, ocular signs (slit-lamp assessments), dilated fundus examinations, intraocular pressure (IOP), pulse, and blood pressure.

RESULTS AND DISCUSSION

An evaluation of 126 subjects (age range, 3-17) revealed no clinically relevant treatment-related changes in visual acuity, IOP, slit-lamp assessments, fundus examinations, or cardiovascular parameters. All adverse events reported were mild or moderate.

CONCLUSIONS

Olopatadine 0.2% administered once-daily for 6 weeks is safe and well tolerated in children and adolescent patients.

Pharmacotherapy of allergic eye disease

Allergic eye disease is a term that refers to a number of disease processes that affect about one-fifth of the world's population. Although the more advanced forms of the disease can be sight threatening, the most disabling effects are due to the clinical manifestations, and hence quality of life, with some patients having seasonal exacerbations of their symptoms, whereas others have symptoms that are present throughout the year. Recent increased understanding of the cellular and mediator mechanisms that are involved in the various disease manifestations has greatly facilitated the development of more effective treatment options. Newer topical medications are being used that have multiple actions, such as an antihistaminic effect coupled with mast-cell stabilisation, and which require reduced daily dosing due to their longer duration of action. With greater research into newer therapies and more effective modes of delivery, improved healthcare outcomes with a lower economic burden will be achieved for patients with allergic eye disease.

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.

Efficacy and response with olopatadine versus epinastine in ocular allergic symptoms: A post hoc analysis of data from a conjunctival allergen challenge study

OBJECTIVES

This post hoc analysis used data from a previous study to more precisely evaluate the efficacy of olopatadine hydrochloride and epinastine hydrochloride in alleviating various levels of severity of ocular itching and conjunctival redness and to determine whether there were any significant differences in the number of responders to treatment.

METHODS

The original study was a randomized, double-masked allergen challenge comparison assessment. Adult patients with allergic conjunctivitis were screened (visits 1 and 2); those who exhibited positive allergic reactions at both visits were randomized to 1 of 3 groups. olopatadine/epinastine, olopatadine/placebo, or epinastine/placebo. At visit 3, each eye was treated with study medication, and then challenged with allergen. Itching, redness, and chemosis assessments were recorded. For the present post hoc analysis, each eye in the olopatadine/epinastine group was separately classified at each time point, based on the pretreatment severity of their symptom (itching) and sign (conjunctival redness) scores, as moderate, moderate/severe, or severe. Data were analyzed to determine responders (eyes with itching and/or conjunctival redness scores of 0 [none]).

RESULTS

Of 96 patients screened, 66 were randomized to treatment (36 women, 30 men; mean age, 44.38 years [range, 20-71 years]). Olopatadine-treated eyes exhibited lower mean itching scores than epinastine-treated eyes in the moderate/severe and severe groups at all 3 time points (3, 5, and 7 minutes), with significance in the moderate/severe group at 5 minutes (P = 0.05) and in the severe group at 5 and 7 minutes (P = 0.017 and P = 0.02, respectively). Olopatadine-treated eyes had mean conjunctival redness scores similar to epinastine-treated eyes in all severity groups at all time points (10, 15, and 20 minutes) except in the severe group at 10 minutes (P = 0.03). On response analysis, for itching, the proportion of responders was significantly greater in the olopatadine group versus the epinastine group 7 minutes after challenge (27 [50.9%] vs 14 [26.4%]; P = 0.016). For conjunctival redness, the proportion of responders was significantly greater with olopatadine treatment versus epinastine treatment at 15 and 20 minutes after challenge (15 minutes, 12 [22.6%] vs 1 [1.9%] [P = 0.002]; 20 minutes, 10 [18.9%] vs 1 [1.9%] [P = 0.008]).

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.