A Fade-Away Injection

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Science  28 Mar 2008:
Vol. 319, Issue 5871, pp. 1735
DOI: 10.1126/science.319.5871.1735d

Although a number of drugs can be delivered via a transdermal patch, this pain-free method generally does not match the efficacy of a needle injection. In a hybrid approach, Lee et al. fabricated microneedle arrays out of two biocompatible polysaccharides, carboxymethylcellulose (CMC) and amylopectin. A key to making robust needles was pre-concentration of the aqueous polysaccharide solutions before casting the needles in a polymer mold. The strength of the microneedles depended on shape, because cylindrical CMC needles were not strong enough to penetrate skin, although pyramidal ones were. Drugs could be loaded into the needles themselves, into a backing layer, or both, depending on whether dosing required a bolus shot or a more prolonged delivery. On contact with skin, the microneedles dissolved, releasing the drug and creating pathways for transport from the backing layer. Using lysozyme as a model protein, the authors showed that it was possible to store the arrays for up to 2 months with almost no loss of enzymatic activity. — MSL

Biomaterials 29, 2113 (2008).

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