Thumb-sized test patches contain 50 stainless-steel microneedles each about 0.025-in. long. These allow replacing a 50 mg tablet with 10 to 12 mg of drug in gel. Microneedles also produced steady bloodstream levels of the drug without the initial peak that occurs with oral delivery.

Researchers at the University of Kentucky and the Georgia Institute of Technology say that pads filled with drugs and fitted on one side with microscopic needles can transdermally and painlessly deliver drugs that normally cannot pass through the skin. The study shows small needles can administer drugs, proteins, and vaccines into the body. The researchers also found that the microneedles delivered therapeutic drug levels with lower doses, and led to fewer side-effects causing metabolites.

“This method may be useful for a broad range of drugs that are normally delivered by hypodermic needle,” says Mark Prausnitz, professor in the Georgia Tech School of Chemical and Biomolecular Engineering. Transdermal administration has advantages over other delivery techniques, but existing systems are used for a narrow range of compounds that easily pass through the skin. Until this study, drug delivery by microneedles involved only animals and human-cadaver skin.