Immediate topical drug delivery by natural submicron injectors.

Transdermal delivery is an attractive but challenging solution for delivery of drugs. The sea anemone possesses a sophisticated injection system, which utilizes built-in high osmotic pressures. The system is folded within microcapsules and upon activation it injects a long, needle-like tubule of submicron diameter that penetrates the target in a fraction of a second. Here we show that this natural injection system can be adapted for active topical drug delivery once it is isolated from the cells, formulated into a topical gel, and uploaded with the desired drug. The formulated injectors retained their physical characteristics and were capable of penetrating the skin, achieving immediate delivery of a hydrophilic compound. We demonstrate quantitative rapid delivery of lidocaine hydrochloride as a function of microcapsular and drug concentrations. The adaptation of natural injectors for drug delivery combines the benefits of short topical application with rapid delivery of physical devices, thereby presenting a promising alternative for transdermal drug delivery.