SLIT Tablets: Tough Choices for Practice
Published: Mar 4, 2014
By Crystal Phend, Senior Staff Writer, MedPage Today
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SAN DIEGO -- As sublingual immunotherapy (SLIT) tablets near clinical practice, allergists here debated how to select patients and whether to routinely prescribe epinephrine auto-injectors.
FDA advisory panels recommended approval of the first SLIT tablets -- one for ragweed (Ragwitek), another for Timothy grass (Grastek), and a third for multigrass pollen (Oralair) -- over the past several months.
If the agency follows that advice, which it is expected to do within the year, physicians will have to choose between tablets and subcutaneous immunotherapy (SCIT) or off-label drops derived from those extracts.
Efficacy isn't likely to be a deciding factor, Thomas Casale, MD, told attendees at the American Academy of Allergy, Asthma, and Immunology meeting.
While there have been no high-quality trials comparing SCIT with SLIT, the available evidence suggests largely equivalent effectiveness in easing allergy symptoms, said Casale, of the University of South Florida in Tampa and executive vice president of the academy.
Where SLIT distinguishes itself is in clearly greater safety, he suggested.
Its disadvantage is that tablets under development for other allergens, such as dust mites, won't reach the market for some time, noted Michael Blaiss, MD, of the University of Tennessee Health Sciences Center in Memphis.
One audience member at his interactive talk at the meeting pointed out that few patients are allergic to only grass or only ragweed.
"What's the advantage of SLIT if you have to have them come in for shots of other allergens as well?" he asked.
Blaiss, a past president of the academy, recommended determining which of a patient's allergies are clinically relevant, relying on a good history and physical exam.
If all are causing symptoms, then SCIT may be the better option, he agreed.
Sublingual drops mixed from extracts used for allergy shots are available for the full gamut of allergens and could make sense for patients who can't adhere to injections, Blaiss noted.
However, he cautioned about practical problems in reaching effective doses for multiple allergens with SLIT drops.
For example, to reach the therapeutic dose of ragweed allergen shown effective in trials, the drops for that allergen alone would take up as much volume as can be held under the tongue without spilling out, Blaiss said.
"If you mix any other allergen with the ragweed, in fact, you would dilute it out and you would not get a therapeutic effect," he told attendees, citing this as the reason he doesn't use SLIT drops in his practice.
The label for SLIT tablets are likely to specify that patients get their first dose in the clinic and have an epinephrine auto-injector available to them, as was the case in the clinical trials, Blaiss noted.
But those devices are not routinely prescribed or recommended in other countries where SLIT tablets have already been approved, Linda Cox, MD, president of the AAAAI, noted at a "nuts and bolts" talk.
Audience members voiced disparate opinions, citing a need to practice defensive medicine and the extremely low anaphylaxis risk with the immunotherapy tablets in the literature, and yet others suggesting they would follow their practices' varying policies for SCIT.
Another contentious issue was impact on adherence.
Many argued that having monitored dosing and reminders from the office for SCIT produce better adherence, but others countered that injections and need for time-consuming office visits cause patients to drop out of treatment.
Adherence with SLIT drops appears just as poor as with SCIT, and cost may be a significant factor, Cox noted.
Blaiss agreed, noting that patients have had to pay out of pocket for the extract solutions while increasing copays and deductibles have been driving a decrease in SCIT use his practice.
"If SLIT is approved in the United States, it will be by prescription so the coverage would be like any other drug, different than the way we do SCIT where we code for it and bill for it," he said. "Cost is a major driver in what patients will do and the adherence rate."
Once the tablets get approved, the specter of turf may rise as other specialties like ear, nose, and throat and primary care could prescribe SLIT too.
But most primary care physicians wouldn't be willing to administer the first couple of doses in their offices given the high prevalence of adverse events with those doses, Casale suggested.
Quality measures requiring demonstration of allergen-specific immunoglobulin E before administration might be a restraint as well, Cox suggested.
"You can't prevent people from doing various things," she concluded.