A medical device comprising a composition comprising a therapeutically active amount of active agent, a zinc compound, and an array of microneedles. The zinc compound may be selected from the group consisting of zinc, pharmaceutically acceptable salts of zinc, and mixtures thereof. At least a portion of the composition is present as a coating on at least a portion of the microneedles. Methods of delivering a therapeutically active agent to a mammal using compositions of the disclosure are also included.