An extract of Timothy-grass pollen used as sublingual immunotherapy for summer hay fever.

Grazax is a lyophilisate of an extract of Timothy-grass pollen (Phleum pratense) administered by the sublingual route to induce desensitization (or hyposensitization) to grass pollen in subjects with hay fever. Since allergen avoidance measures are limited in hay fever sufferers, present treatment, at least in the United Kingdom, is almost always by symptomatic medication. The effectiveness of symptomatic treatment in hay fever is variable and depends on patient compliance and the judicious prescribing of antihistamines and anti-inflammatory preparations either alone or in combination. Desensitization (hyposensitization or specific immunotherapy) by subcutaneous injection has been shown to be very efficacious and is used for patients who do not adequately respond to drug treatment. A rare side effect of desensitizing injections is anaphylaxis, and so use is limited to specialized centers. For these reasons there has been considerable interest in specific immunotherapy by the sublingual route. Grazax has recently been approved in the United Kingdom. It is commenced at least four months prior to the expected start of the grass pollen season and in line with injection immunotherapy treatment will be recommended for a period of three years with annual reviews to assess patient outcomes. Grazax grass allergen tablets are well tolerated in patients with grass pollen allergy with most adverse events being mild local reactions. There have been no instances of anaphylaxis. In randomized double-blind placebo controlled trials Grazax reduces symptoms and medication scores in adults with hay fever. The long-term effects of Grazax are currently being investigated.