Micro needles can be highly effective and minimally invasive. Photo credit: Sahan Ranamukhaarachchi
Among the many innovations that the original Star Trek series offered to illustrate how much more comfortable life in the future could be, perhaps none was more intimate than the delivery of medicine into a patient’s body. In place of today’s hypodermic needles, Dr. Leonard “Bones” McCoy of the USS Enterprise used apparently painless injections called a hypospray that barely grazed the skin.
That imagery stayed with Sahan Ranamukhaarachchi, who has turned it into a centrepiece of his career. Now a doctoral student in electrical and computer engineering at the University of British Columbia, he previously studied food engineering and chemical engineering, with a keen interest in nutraceutical and pharmaceutical products. Along the way Ranamukhaarachchi began to examine how agents such as vaccines are delivered, which led him to consider alternatives to the traditional class of needles.
While a great many of these needles have gotten thinner over the years — shrinking from a standard diameter of about 1.3 millimetres to only 0.3 millimetres — the smallest is still about four millimetres in length, which can cause pain by poking through the skin into sensitive muscle layers below. “Over the past decade, there has been a lot of research in the area of micro-injection,” he says, referring to needles on the order of 200 to 800 micrometres in length. “When you press them against your skin, they don’t penetrate deep enough into the tissue to cause you any pain. All you feel is a slight pressure.”
Nevertheless, such needles actually turn out to be more effective because the skin serves as a superior delivery medium, acting like a highly efficient sponge that sops up and disperses the injection. In fact, skin is packed with antigen-sensitive cells that respond rapidly to the contents of a vaccine, which means less medicine needs to be used. “For rabies, for example, you only need one-tenth of the standard dose if you inject the vaccine into the skin, compared to injecting into muscle,” Ranamukhaarachchi says. That savings can add to the capability of health authorities working in difficult settings such as the developing world, where rabies and infectious diseases remain a much more widespread threat but the cost of vaccines might limit their accessibility.
Ranamukhaarachchi adds that micro-needles also minimize the risk of accidental needle sticks, a hazard that often leads to individuals acquiring serious infections from needles that have been exposed to viruses or bacteria. In the United States alone there are some 500,000 reported cases of this problem every year, posing a serious challenge in many clinical settings.
Two years ago, Ranamukhaarachchi and his colleagues began to develop micro-needle technology commercially through a UBC-based spin-off company called Microdermics, which recently received the top award at the New Ventures BC 2016 competition. The company’s work has moved beyond the concept of tradition drug injection to prospects such as allergy testing devices or minimally invasive biosensors. This work is approaching Phase 1 human clinical trials, which should be completed by next spring.