Local nasal specific immunotherapy for allergic rhinitis

Abstract

The possibility of producing local hyposensitization by administering allergens via mucosal routes was envisaged at the beginning of 1900, and local nasal immunotherapy has been extensively studied since the 1970s. Presently, there are 21 randomized controlled trials being conducted with the most common allergens, consistently showing the clinical efficacy of local nasal immunotherapy for rhinitis. Other advantages are that it has an optimal safety profile and can be self-administered at home by the patient. Moreover, there are several data from animal models and from humans that confirm the immunomodulatory effect of intranasally administered antigens. On the other hand, local nasal immunotherapy seems to be effective only on rhinitis symptoms and requires a particular technique of administration. For these reasons, its clinical use is progressively declining in favour of the sublingual route although nasal immunotherapy is validated in official documents and remains a viable alternative to injection.

Figure 1

Example of an administration schedule for local nasal immunotherapy (LNIT) with an aqueous extract prepared at different concentrations. UB = biologic units; Wk = weeks.

Figure 2

Diagram of a delivery device for extracts prepared as dry-powder capsules (Allerkin, Lofarma S.p.A, Milan, Italy).

Figure 3

Graph showing how the intensity of nasal response to rechallenge is different at different times. If the rechallenge is made 2 weeks after the first challenge, a significant reduction in the response is seen. Adapted from Nickelsen JA et al [41]. d = days; NS =

Figure 4

Pharmacokinetics of radiolabelled Par j 1 in a nonallergic volunteer. Sequential scintiscans of the nasal region, recorded at different times (up to 30 minutes) after administration, show a progression of the allergen toward the pharynx.