Cetirizine from topical phosphatidylcholine-hydrogenated liposomes: Evaluation of peripheral antihistaminic activity and systemic absorption in a rabbit model

Cetirizine, an effective, minimally sedating, second-generation H1-antihistamine is widely used orally to treat allergic skin disorders. This study was performed to assess the peripheral H1-antihistaminic activity and extent of systemic absorption of cetirizine from liposomes applied to the skin. Cetirizine was incorporated into small unilamellar vesicles (SUV) and multilamellar vesicles (MLV) prepared using L-α-phosphatidylcholine hydrogenated (HPC), and into Glaxal Base (GB) as the control. In a randomized, crossover study, each formulation, containing 10 mg of cetirizine, was applied to the depilated backs of 6 rabbits (3.08±0.05 kg). Histamine-induced wheal tests and blood sampling were performed before cetirizine application and at designated times for up to 24 hours afterwards. Compared with baseline, histamine-induced wheal formation was suppressed by cetirizine in SUV only at 24 hours, in MLV from 0.5 to 24 hours, and in GB from 0.5 to 8 hours (P<.05). Wheal suppression by cetirizine in SUV at 24 hours (91.7%±5.2%) and in MLV from 1 to 24 hours (93.8%±2.2% to 76.2%±6.5%) was greater than in GB (36.5%±7.4% to 60.6%±14.2%) from 1 to 24 hours (P<.05). Faster onset, as well as greater and more persistent suppression was obtained from cetirizine in MLV. Plasma cetirizine concentrations from MLV (area under the curve [AUC] of 221.2±42.3 ng.hr/mL) were lower than from GB (AUC of 248.3±34.6 ng.hr/mL). In this model, cetirizine from MLV had excellent topical H1-antihistamine activity, while systemic exposure was reduced, compared with cetirizine from GB

Hydroxyzine from topical phospholipid liposomal formulations: Evaluation of peripheral antihistaminic activity and systemic absorption in a rabbit model

Hydroxyzine, an effective but sedating H1-antihistamine is given orally to treat allergic skin disorders. This study was performed to assess the peripheral H1-antihistaminic activity and extent of systemic absorption of hydroxyzine from liposomes applied to the skin. Using L-α-phosphatidylcholine (PC), small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs) containing hydroxyzine were prepared. Hydroxyzine in Glaxal Base (GB) was used as the control. Using a randomized, crossover design, each formulation, containing 10 mg of hydroxyzine, was applied to the shaved backs of 6 rabbits (3.08±0.05 kg). Histamine-induced wheal tests and blood sampling were performed at designated time intervals up to 24 hours. Compared with baseline, hydroxyzine from all formulations significantly suppressed histamine-induced wheal formation by 75% to 95% for up to 24 hours. Mean maximum suppression, 85% to 94%, occurred from 2 to 6 hours, with no differences among the formulations. The areas of plasma hydroxyzine concentration versus time area under the curve (AUCs) from PC-SUV and PC-MLV, 80.1±20.8 and 78.4±33.9 ng/mL/h, respectively, were lower than that from GB, 492±141 ng/mL/h (P<.05) over 24 hours. Plasma concentrations of cetirizine arising in-vivo as the active metabolite of hydroxyzine, from PC-SUV, PC-MLV, and GB, were similar with AUCs of 765±50, 1035±202, and 957±227 ng/mL/h, respectively (P<.05). Only 0.02% to 0.06% of the initial hydroxyzine dose remained on the skin after 24 hours. In this model, hydroxyzine from SUV and MLV had excellent topical H1-antihistaminic activity, and minimal systemic exposure occurred. Cetirizine formed in-vivo contributed to some of H1-antihistaminic activity