Coatable compositions and coatings derived from the coatable compositions, and microarrays comprising such coatings are described. In one aspect, the invention provides a microarray comprising: a plurality of microneedles extending from a support substrate; a coating deposited on at least one of the plurality of microneedles, the coating comprising an active agent and a biological salt. In another aspect, the invention provides a coatable composition, comprising: active agent; a biological salt; and solvent. In still another aspect, the invention provides a dried coating coated on a microneedle, the coating comprising: an active agent; and a biological salt.