By David Warmflash
When Star Trek first aired during the 1960s, most of the imaginary technologies seemed appropriate for a setting two to three centuries into the future—excluding those 20th century plastic spray bottles that you might use to mist the leaves of a house plant. But that part has changed quickly over the last 45 years, especially in the realm of medicine. Previously, I’ve discussed the fictional antiradiation drug hyronalin, making its way from science fiction to science fact, and I mentioned a real-life medical tricorder under development.
Another Star Trek health innovation that’s essentially already here and subject to rapid improvement in the years to come is what they called a “hypospray,” referring to needle-free injection, which can particularly make things easier for pharmacists. Over the last several years, pharmacists have played an increasing role in the administration of vaccines, most of which are injected intramuscularly. Furthermore, many patients have to inject themselves in various situations. This is a common scenario in the case of insulin-dependent diabetics, a group that includes many children who require injections everyday (usually more than once). It also includes people with severe allergies to certain foods or bee stings; they, or their parents, must carry an injector at all times for emergency treatment with fast-acting agents such as epinephrine.
But whether at the drug store, in a clinic or hospital setting, or by one’s own hands or those of a family member, injection through a needle entails several disadvantages. First, most patients do not like needles. Even though injection with a high-gauge needle does not trigger many pain receptors when given quickly and correctly, many people, especially children, have trypanophobia, or fear of needles. They are anxious about the idea of an object pricking through their flesh and leaving a drop of blood, which may be one reason why many people avoid vaccinations. Second, needle injection often leads to soreness at the injection site, or even referred pain at other locations. Needles can break, and they also need to be recapped and put through sharp biohazard disposal protocol, since injection puts them into contact with body fluids. Recapping and disposing of injection needles places the operator at risk of a needle prick. If they are pricked, this initiates a series of procedures to evaluate their exposure risk, and, if needed, to begin treatment for infective agents transmitted in body fluids, such as HIV and the various types of hepatitis. Although the incidence of needle pricks decreases as one’s skill level increases, studies show that health care workers in training are at particularly high risk.
To avoid all of these problems, several devices similar to Dr. McCoy’s hypospray are under development, and some are already in use for administering certain agents. All are based on the principle that you can force a drug through the skin and underlying tissues, using very high pressure concentrated in a very narrow jet of liquid. One jet injector developed at MIT, for instance, can shoot a drug solution through the skin at up to 340 meters per second. Another injector, called Pharmajet, is in use for vaccine administration.
Because the stream is no thicker than the proboscis of a mosquito, and because the process takes under a millisecond, patients injected with these devices do not feel anything, except for the tip of the injector against the skin.
The MIT injector is so powerful that it also can deliver drugs in powder form, plus it can be used to withdraw body fluids, such as a blood sample. Given these capabilities, the MIT researchers are actually calling the device a hypospray, although it’s not reported to inject through a shirt (as I distinctly remember Bones McCoy doing frequently). On the other hand, there is no reason why the jet shouldn’t be able to shoot through a shirt, if the sleeve is thin and tight. In health care, we’d still want to inject directly through skin that has been swabbed with alcohol, but shirt-penetrating capability might be useful for those needing to render one of Khan Singh’s thugs unconscious.
David Warmflash, M.D., is an astrobiologist, science writer, and physician. He is principal investigator on a Planetary Society-sponsored investigation of the effects of the space environment on organisms.