Promising New Eyedrops for Allergic Conjunctivitis.
"It works, it is safe down to age 3, you only need to use it two or three times per day, it rarely stings, and it is inexpensive. In my experience, it is pure compliance," said Dr. Granet, a pediatric ophthalmologist at the University of California, San Diego. "I use it myself."
Topical ocular antihistamine-decongestants such as levocabastine and emadine can block histamine action at the [H.sub.1]- and [H.sub.2]-receptors in the conjunctiva, but do not slow the constant release of histamine from conjunctival mast cells.
So patients must dose repeatediy--a hassle since these medications tend to sting.
"Histamine is a major mediator, but it doesn't work alone in the process of allergic rhinitis. There are lots of others," he explained. As allergen exposure persists, mast cell mediator production and release increase. The mast cells migrate closer to the surface of the conjunctiva, intensifying redness, itchiness, and runniness. "If you want to control the symptoms, you ultimately need to take care of those mast cells."
Ocular mast cell stabilizing drugs such as lodoxamide and cromolyn sodium can block the release of preformed mast cell mediators and reduce the generation of new inflammatory mediators, But these agents also require application 4-6 times per day, and the onset of action is slow Patients often need to use the drops for at least 1 week before experiencing the benefit.
Olopatadine 0.1%, marketed as Patanol, acts almost instantly, said Dr. Granet, who has no financial relationship with the drug's manufacturer. By reducing mast cell mediator formation and blocking histamine binding, olopatadine attenuates conjunctival inflammation and congestion at both "ends" of the process.
This new agent has caught on fast in the ophthalmologic community, generating sales of about $100 million last year. Patanol is now being more aggressively promoted to allergists and primary care physicians, who see large numbers of patients with allergic conjunctivitis.
According to Dr. Dennis Spangler, chief medical officer of the Atlanta Allergy & Asthma Clinic, twice-daily dosing is a major advantage. "You can go up to three times per day, but you rarely need to."
A bottle of the new medication costs about $74 and lasts roughly 2 months. With twice-daily dosing, the daily cost is about $1.23. This is comparable to the cost of ophthalmic cromolyn, and lower than that of the ophthalmic antihistamine, levocabastine, which costs approximately $2.35 per day, said Dr. Spangler, who is on the speakers' board for a number of drug companies, including Alcon Laboratories Inch the maker of olopatadine.
Olopatadine is an excellent addition to front-line therapies for allergic conjunctivitis, but other medications still have a role. Lodoxamide, the mast cell stabilizer, is an excellent preemptive agent. "If a patient knows he is going to visit Aunt Sally, the cat lover, he can use lodoxamide before the visit and avoid the allergic reaction," he said.
Oral antihistamines also can be effective in reducing symptoms of allergic conjunctivitis, not to mention the concurrent nasal and sinus symptoms. But these drugs tend to reduce production of tears, leading to ocular dryness and irritation.
Nonsedating antihistamines may be slightly less drying and are probably the better choice for persistent ocular symptoms. Concurrent use of olopatadine with a nonsedating antihistamine improves symptoms to a degree not obtainable with antihistamine alone, Dr. Spangler added.
|Printer friendly Cite/link Email Feedback|
|Author:||GOLDMAN, ERIK L.|
|Publication:||Family Practice News|
|Article Type:||Brief Article|
|Date:||Jan 1, 2000|
|Previous Article:||Deciding When to Refer a Child to an Allergist.|
|Next Article:||Allergen Elimination Begins in the Bedroom.|