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Testosterone patches are already used to deliver the hormone into a person's bloodstream in a controlled way and over an extended period of time.

Forget phobia-inducing needles. Scientists are developing skin patches that can deliver most drugs without inflicting pain and suffering.

Information technology giant Hewlett Packard announced Tuesday that it had employed its ink-jet printercartridge technology to create a patch that releases drugs through the skin in a controlled and painless way.

The company said it has licensed the patch to Crospon, an Irish medical device developer, who will manufacture theinvention and make it available to pharmaceutical firms.

The skin patch uses tiny needles that barely penetrate the skin, allowing medication to enter the bloodstream in precise doses.

Patches are already sold to people who want to quit smoking or need a hormone boost. Butthey have not proven effective in delivering all drugs because the skinacts as anatural barrier to many chemicals, the company said.

HP's announcement followsresearch on a similar needle-free drug delivery system developed at the University of California in 2005. Calleda microjet, it's a transducer-based pulsed device that allows the controlled and shallow delivery of drugs through the skin.

It works by delivering a jolt of electricity toa kind ofplunger thatforces the drug from a reservoir into the skin at a high velocity. Like the HP patch, the microjet acts like a printer, printing drugs precisely into the skin. It can be used over a long period of time for sustained drug delivery — and itallows patients to forgo painful injections.