Pharmacokinetics of an allergen and a monomeric allergoid for oromucosal immunotherapy in allergic volunteers.
OBJECTIVE
Little is known about the pharmacokinetics of allergens for local immunotherapy. Thus, we studied the pharmacokinetics in allergic volunteers of a commercial allergenic vaccine in orosoluble tablets (LAIS(R), Lofarma S.p.A).


METHODS
The carbamylated monomeric allergoid derived from Parietaria judaica major allergen (Par j 1), characterized by maintenance of the original molecular size, and the native allergen, were radiolabelled with 123I, then incorporated into the commercial soluble tablets and administered to allergic subjects. Early sequential and late static scintigraphic acquisitions were performed, and plasma radioactivity was measured at different time intervals.


RESULTS
No difference in local pharmacokinetics was observed between the allergen and the allergoid: part of the tracer was retained in the mouth for at least 2 h after swallowing. No direct absorption through the oral mucosa could be detected, as plasma radioactivity increased only after swallowing and peaked at 2 h. However, the plasma peak attained with the allergoid in tablets was significantly higher with respect to the native allergen. Finally, some undegraded allergoid, but not the allergen, could be constantly detected in the bloodstream at plasma peak.


CONCLUSIONS
The results showed a similar behaviour of the allergoid and the allergen in tablets as far as their local kinetics are concerned, whereas plasma peak was higher with the allergoid than with the allergen. Therefore we conclude that the chemical modification of the allergen may affect its pharmacokinetics, by making it less susceptible to enzymatic degradation.
Bagnasco
M
M
Allergy and Clinical Immunology, Department of Internal Medicine, Genoa, Italy.
Passalacqua
G
G
Villa
G
G
Augeri
C
C
Flamigni
G
G
Borini
E
E
Falagiani
P
P
Mistrello
G
G
Canonica
G W
GW
Mariani
G
G
D000286:Administration, Sublingual; D000328:Adult; D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000080384:Allergoids; D003888:Desensitization, Immunologic; D005260:Female; D006023:Glycoproteins / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D006801:Humans; D007457:Iodine Radioisotopes / Q000097:blood; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D010940:Plant Proteins / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D011877:Radionuclide Imaging; D012130:Respiratory Hypersensitivity / Q000628:therapy; D014612:Vaccines / Q000276:immunology / Q000493:pharmacokinetics*
D000485:Allergens; D000080384:Allergoids; D006023:Glycoproteins; D007457:Iodine Radioisotopes; C083860:Par j I protein, Parietaria judaica; D010936:Plant Extracts; D010940:Plant Proteins; D014612:Vaccines