Kofi Nyam

Macroflux Microprojection Array Patch Technology: A New and Efficient Approach for Intracutaneous Immunization

AbstractPurpose. We evaluated the Macroflux® microprojection array patch technology as a novel system for intracutaneous delivery of protein antigens. Methods. Macroflux® microprojection array systems (330-μm microprojection length, 190 microprojections/cm2, 1- and 2-cm2 area) were coated with a model protein antigen, ovalbumin (OVA), to produce a dry-film coating. After system application, microprojection penetration depth, OVA delivery, and comparative immune responses were evaluated in a hairless guinea pig model. Results. Macroflux® microprojections penetrated into hairless guinea pig skin at an average depth of 100 μm with no projections deeper than 300 μm. Doses of 1 to 80 μg of OVA were delivered via 1- or 2-cm2 systems by varying the coating solution concentration and wearing time. Delivery rates were as high as 20 μg in 5 s. In a prime and boost dose immune response study, OVA-coated Macroflux® was most comparable to equivalent doses injected intradermally. Higher antibody titers were observed when OVA was administered with the microprojection array or intradermally at low doses (1 and 5 μg). Macroflux® administration at 1- and 5-μg doses gave immune responses up to 50-fold greater than that observed after the same subcutaneous or intramuscular dose. Dry coating an adjuvant, glucosaminyl muramyl dipeptide, with OVA on the Macroflux® resulted in augmented antibody responses. Conclusions. Macroflux® skin patch technology provides rapid and reproducible intracutaneous administration of dry-coated antigen. The depth of skin penetration targets skin immune cells; the quantity of antigen delivered can be controlled by formulation, patch wearing time, and system size. This novel needle-free patch technology may ultimately have broad applications for a wide variety of therapeutic vaccines to improve efficacy and convenience of use.

Pharmacokinetic study of dexamethasone disodium phosphate using intravitreal, subconjunctival, and intravenous delivery routes in rabbits.

Dexamethasone is a corticosteroid with proven efficacy for treating both anterior- and posterior-segment ocular diseases. Delivery of drugs to the back of the eye has always been a challenge, with dexamethasone being no exception. There are multiple delivery routes to the retina, with each exhibiting different pharmacokinetics, depending on the drug molecule and specific route of administration. In this study, we used intravenous (IV), subconjunctival (SC), and intravitreal (IVT) injections in rabbits to determine the pharmacokinetics of dexamethasone phosphate and its metabolic product, dexamethasone, at low (25 microg/kg) and high (250 microg/kg) doses. Plasma samples were collected from each group of animals at different time points up to 24 h after the injection. Using a liquid chromatographic mass spectrometric method with a limit of detection of 0.5 ng/mL, the plasma concentration for dexamethasone and its prodrug compound were quantified. IV delivery showed the fastest plasma elimination, followed by SC delivery. IVT delivery exhibited a depot effect, with very low plasma levels throughout the 24-h time course. At 24 h postinjection, only the high-dose IVT and low- and high-dose SC dexamethasone injections were still detectable in the plasma.