A team of University of British Columbia scientists believes it's on the verge of developing a drug-injection method that’s painless and wouldn't require conventional hypodermic needles to be plunged deep into the tissue.
"We call them microneedles, or microneedle arrays," said Dr. Boris Stoeber, the associate professor whose lab is creating the alternative injection method.
"It looks like a flat metal plate. You won't see it well with your eyes, but you'll see some roughness. If you feel it, it feels rough. If you press it against your skin, you feel pressure, but not pain."
Stoeber, who is also the Canada Research Chair in Microfluidics and Sensing Technologyhas. has been working on the microneedles project since 1999. He compares the feeling of using one of the eight-millimetre-squared patches to pressing some coarse sandpaper against the flesh.
Tiny needles only reach outer layer of skin
The new drug-delivery system would look less like a traditional hypodermic needle and a lot more like a shred of foil dotted with microscopic volcanoes — each tiny pillar capable of penetrating the outermost layer of our skin just enough to deposit a dose of medication.
One array might have 50 to 100 of the microneedles, with a reservoir of medication contained beneath.
The impact could be big, Stoeber said. He imagines microneedles benefiting people with diabetes who must check blood glucose levels by using sometimes painful finger-pricking devices.
“We also definitely think microneedles are a good application for vaccines,” he said.
Human skin is composed of two main layers. The stratum corneum is the outermost layer of the epidermis, and it would be the only layer that would get punctured by the small pillars on the microneedle patch.
"From the epidermis, the drug would diffuse to the blood vessels that are in the next layer of the skin, the dermis," Stoeber said.
People who suffer from trypanophobia, or a fear of needles, often have anxieties about the pain associated with conventional hollow hypodermic needles because inserting them can touch sensitive nerves.
In clinical trials conducted in 2004 with Stoeber’s patch, subjects were able to use them to administer doses of a vasodilator (medication that widens the blood vessels) to their bodies.
"These clinical trials demonstrated that microneedles are effective for transdermal drug delivery, and the patients reported the absence of pain during the injections," he said.
Stoeber said the effectiveness of the prototype was easy to measure by tracking the subjects’ increased blood flow.
“If you have a pre-filled reservoir with the drug on the backside, and you could ship this readily filled to the users or the patients, this would make administration much, much easier,” he said.
He also notes that the arrays won't just be painless, but cheap to produce.
10 cents a patch
"It'll probably be on the order of 10 cents per patch," he said.
The silicon needles have been tested on mice.
Although early versions were fabricated with silicon, one of Stoeber's students, Iman Mansoor, found it would be far less expensive to create a metal coating through the process of electroplating a polymer mold.
Stoeber himself has bad memories of needles, having suffered from hay fever as a 10-year-old growing up in Germany.
“I don’t like needles. For several years, I had regular allergy-related injections, and it was definitely very uncomfortable,” he said. “That was a little bit of a personal motivation to develop these painless needles.”
He hopes a version of the microneedle array will be put on the market by 2018.
In the meantime, Stoeber’s lab is working towards getting another human clinical trial and tweaking designs to optimize the shape of the needles so they can be more effectively inserted into the skin.