Making an Impact On Allergies
Making an Impact On Allergies
A combination antihistamine and mast cell stabilizer offers immediate and long-term action.
By Laurie Sorrenson, O.D., F.A.A.O.
The 2003-2004 Gallup Study of Allergy reports that as many as 50% of the U.S. population is affected by allergies. Of these, 83% suffer ocular symptoms. This translates to about 120 million Americans with ocular allergies, and in the spring, it feels like all of them are coming to see us.
Most allergic conjunctivitis cases are seasonal (SAC) or perennial (PAC), and treatment for both types should be directed at the underlying etiology of the disease. As I'll discuss here, studies show that a dual-action, daily-dose medication that combines an antihistamine and a mast cell stabilizer is a safe, effective and convenient option.
Behind the itch
Itching is the hallmark sign of SAC or PAC. Your patients' eyelids are swollen, and their eyes are red, chemotic and watery. Scrapings show elevated eosinophils. Whether the problem is seasonal (pollens) or perennial (dust mites, animal dander and mold), your patients' allergies are causing ocular surface inflammation and maddening discomfort.
Ocular allergies result in swollen eyelids and red, chemotic watery eyes.
|Allergies cause mast cell degranulation and the release of histamines and proinflammatory mediators. Therefore, the most effective medications will address both problems.|
The allergic reaction is triggered by antigens, which cross-link with the immunoglobulin E antibody (IgE) on the mast cells, leading to mast cell degranulation. This, in turn, releases histamines and proinflammatory mediators, such as prostaglandins, tryptase and heparin. The histamine quickly binds with H1 receptor sites on the nerves and causes itching. It also binds to H1 receptor sites on the blood vessels, causing redness, chemosis and fluid leakage. The proinflammatory mediators only add to the redness and swelling, and there's no end in sight, because antigens continue to bombard the eyes as part of the inflammatory cascade.
If we follow the etiology of allergic conjunctivitis, we can discern some important information. With 50 million mast cells in the human conjunctiva, the mast cell is central to the ocular allergic response. Allergies cause mast cell degranulation and the release of histamines and proinflammatory mediators. Therefore, the most effective medications will address both problems and will rapidly relieve symptoms.
Antigens that cross-link with the IgE antibody on the mast cells trigger the allergic response. This leads to mast cell degranulation and the release of histamines and proinflammatory mediators.
An antihistamine's mechanism of action is simple. It's attracted to the same H1 receptor sites that histamine seeks. It binds to those sites, effectively blocking the attachment of histamines and preventing itching and redness. Clearly, it's beneficial to put an antihistamine to work early in the inflammatory process.
We also need to use a mast cell stabilizer to effectively treat ocular allergy. These drugs prevent recurrence of the allergic response by inhibiting the release of proinflammatory mediators.
The most commonly prescribed drugs for ocular allergies are olopatadine 0.1% (Patanol, Alcon), olopatadine 0.2% (Pataday, Alcon), epinastine (Elestat, Allergan), ketotifen fumarate (Zaditor, Novartis Ophthalmics) and azelastine (Optivar, Meda Pharmaceuticals Inc.).
Olopatadine 0.1% is the market leader because studies have shown it's clinically effective as a specific H1 antagonist and mast cell stabilizer. It has a quick onset of action, and it's been shown to be comfortable and safe for patients.1–11
In a conjunctival allergen challenge (CAC) study, which compared olopatadine 0.1% to azelastine5 and epinastine11, mean itching scores at 5 minutes were better for olopatadine with statistical significance. The drug also performed better in ocular redness at onset and 10, 15 and 20 minutes post-challenge. Another study showed that olopatadine was significantly more comfortable in the eye than azelastine.6
While results are satisfying, another factor has driven the development of another olopatadine formulation: olopatadine 0.2%. Some studies show overall improvements in adherence, patient quality of life, patient satisfaction and cost when patients can dose less frequently.12 What's more, 95% of allergy patients say that a long-lasting allergy medication is important, so they may be more satisfied if they can use fewer drops.13
A once-a-day drug like olopatadine 0.2% could improve compliance over olopatadine 0.1%, and increased compliance through daily dosing has been shown to give patients better symptom control.12 In an in vitro animal comparison of the two concentrations, olopatadine 0.1% lasted 14 to 15 hours, compared to 24 hours for olopatadine 0.2%.14
Indicated for the treatment of ocular itching associated with allergic conjunctivitis, olopatadine 0.2% has the same safety profile as olopatadine 0.1%. Olopatadine 0.2% has an increased concentration and longer duration, which is why patients need to use it only once a day.15,16
An antihistamine is attracted to the same H1 receptor sites that histamine seeks. It binds to those sites, effectively blocking the attachment of histamines, thereby preventing ocular itching and redness.
During in vitro studies, both doses of olopatadine thwarted the biphasic process that degranulates mast cells and releases mediators, while epinastine, azelastine and ketotifen did not.17,18
In more than 10 clinical trials, more than 1,000 patients have been exposed to olopatadine 0.2%. In a randomized, double-masked, placebo-controlled CAC trial19 that studied 45 people with a history of allergic conjunctivitis, researchers checked patients for itching and redness at onset and after 24 hours. They found that olopatadine 0.2% significantly reduced ocular itching compared to placebo. In the same study, researchers also found a beneficial effect on conjunctival redness.
A multicenter, 10-week study20 looked at the efficacy of olopatadine 0.2% against itching in 260 patients who were sensitive to grass pollen and experienced redness and tearing. They received 1 drop in each eye, once a day. In weekly assessments, patients rated olopatadine 0.2% significantly better than placebo in itching frequency. What's more, the results improved over time as the mast cell stabilizer had time to take effect. Ocular redness fared better than placebo in the same 10-week period.
In addition, the environmental study showed that 0.2% olopatadine was effective, even as allergen levels fluctuated from low to moderate.20
In comparative drug studies, olopatadine 0.2% has continued to fare well. In the double-blind CAC trial21 against epinastine, 92 patients underwent screening, confirmation and an office visit.
Results showed that olopatadine 0.2% reduced itching and redness more effectively than epinastine and also scored well in the comfort comparison index.
|Indicated for the treatment of ocular itching associated with allergic conjunctivitis, olopatadine 0.2% has the same safety profile as olopatadine 0.1%, [but offers] an increased concentration and longer duration.|
Getting an edge
Should you choose olopatadine 0.2% over the 0.1% formulation? I'm beginning to do so because dosing matters. In a 4-week, multicenter trial,14 researchers evaluated 330 patients with a history of allergic conjunctivitis who were taking olopatadine 0.1% and felt satisfied. Some patients were switched to once-daily olopatadine 0.2%. Scores showed that patient satisfaction increased significantly among olopatadine 0.2% users. In their perception, olopatadine 0.2% was comfortable in the eyes (93%) and allowed them to wear contact lenses as desired (87.5%).
We want to be sure that we provide the most effective therapy. We want an antihistaminic effect because the patient feels it immediately. And we want mast cell stabilizing activity to prevent a recurrence of mast cell degranulation. In olopatadine 0.2%, we have a robust option for achieving both of those goals. OM
Dr. Sorrenson is in a group practice in Austin, Texas. She's a part-time faculty member at the University of Houston College of Optometry.
- Butrus S, Greiner JV, Discepola M, Finegold I. Comparison of the clinical efficacy and comfort of olopatadine hydrochloride 0.1% ophthalmic solution and nedocromil sodium 2% ophthalmic solution in the human conjunctival allergen challenge model. Clin Ther. 2000;22:1462-1472.
- Berdy GJ, Spangler DL, Bensch G, Berdy SS, Brusatti RC. A comparison of the relative efficacy and clinical performance of olopatadine hydrochloride 0.1% ophthalmic solution and ketotifen fumarate 0.025% ophthalmic solution in the conjunctival antigen challenge model. Clin Ther. 2000;22:826-833.
- Leonardi A, Zafirakis P. Efficacy and comfort of olopatadine versus ketotifen ophthalmic solutions: a double-masked, environmental study of patient preference. Curr Med Res Opin. 2004;20:1167-1173.
- Aguilar AJ. Comparative study of clinical efficacy and tolerance in seasonal allergic conjunctivitis management with 0.1% olopatadine hydrochloride versus 0.05% ketotifen fumarate. Acta Ophthalmol Scand Suppl. 2000;78:52-55.
- Spangler DL, Bensch G, Berdy GJ. Evaluation of the efficacy of olopatadine hydrochloride 0.1% ophthalmic solution and azelastine hydrochloride 0.05% ophthalmic solution in the conjunctival allergen challenge model. Clin Ther. 2001;23:1272-1280.
- D'Arienzo PA. Poster presented during the annual meeting of the American Academy of Allergy, Asthma & Immunology Annual Meeting, March 15-21, 2001; New Orleans.
- Berdy GJ, Stoppel JO, Epstein AB. Comparison of the clinical efficacy and tolerability of olopatadine hydrochloride 0.1% ophthalmic solution and loteprednol etabonate 0.2% ophthalmic suspension in the conjunctival allergen challenge model. Clin Ther. 2002;24:918-929.
- Lanier BQ, Gross RD, Marks BB, Cockrum PC, Juniper EF. Olopatadine ophthalmic solution adjunctive to loratadine compared with loratadine alone in patients with active seasonal allergic conjunctivitis symptoms. Ann Allergy Asthma Immunol. 2001;86:641-648.
- Lanier BQ, Abelson MB, Berger WE, et al. Comparison of the efficacy of combined fluticasone propionate and olopatadine versus combined fluticasone propionate and fexofenadine for the treatment of allergic rhinoconjunctivitis induced by conjunctival allergen challenge. Clin Ther. 2002; 24:1161-1174.
- Brodsky M, Berger WE, Butrus S, Epstein AB, Irkec M. Evaluation of comfort using olopatadine hydrochloride 0.1% ophthalmic solution in the treatment of allergic conjunctivitis in contact lens wearers compared to placebo using the conjunctival allergen-challenge model. Eye Contact Lens. 2003; 29:113-116.
- Lanier BQ, Finegold I, D'Arienzo P, Granet D, Epstein AB, Ledgerwood GL. Clinical efficacy of olopatadine vs epinastine ophthalmic solution in the conjunctival allergen challenge model. Curr Med Res Opin. 2004;20:1227-1233.
- Richter A, Anton SE, Koch P, Dennett SL. The impact of reducing dose frequency on health outcomes. Clin Ther. 2003;25:2307-2335.
- The 2005 Gallup Study of Allergies — Phase II Report.
- Scoper SV, Berdy GJ, Lichtenstein SJ, et al. Physician assessment, patient perception, and safety of once-a-day olopatadine in treating allergic conjunctivitis. Presented during the annual meeting of the American College of Allergy Asthma and Immunology, Philadelphia, November 2006.
- PATADAY™ Solution [package insert]. Fort Worth, Texas: Alcon Laboratories Inc. 2004.
- Data on file, Alcon Laboratories Inc.
- Yanni JM, Stephens DJ, Miller ST, et al. The in vitro and in vivo ocular pharmacology of olopatadine, an effective anti-allergic/antihistaminic agent. J Ocul Pharmacol Ther. 1996;12:389-400.
- Brockman HL, Momsen MM, Knudtson JR, Miller ST, Graff G, Yanni JM. Interactions of olopatadine and selected antihistamines with model and natural membranes. Ocul Immunol Inflamm. 2003;11:247-268.
- Vogelson C, Abelson MB, Pasquine T, et al. Preclinical and clinical antiallergic effect of olopatadine 0.2% solution 24 hours after topical ocular administration. Allergy and Asthma Proc. 2004;25:69-75.
- Abelson MB, Gomes PJ, Vogelson CT, et al. 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. Clin Ther. 2004;26:1237-1248.
- Mah FS, Rosenwasser LJ, Townsend WD, Greiner JV, Bensch G. Efficacy and comfort of olopatadine 0.2% versus epinastine 0.05% ophthalmic solution for treating itching and redness induced by conjunctival allergen challenge. Curr Med Res Opin. 2007;23:1445-1452.
Optometric Management, Issue: May 2008