Microvesicle Formulations and Contact Allergy - Experimental Studies in In-vitro, Mice and Man

Attempts to improve formulation of topical products are a continuing process and the development of microandnanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics usingthese technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reportedto enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present reportincludes data on more sensitization studies using the mouse local lymph node assay with three contact allergensencapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles.The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophiliccontact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity ofpotassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergendinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared withliposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulatingisoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and inliposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. Theseresults suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizingcapacity of the encapsulated contact allergen.