Needle-Free Injection Devices Face ObstaclesMike Bykowski, Senior Writer
[Skin & Allergy News 30(8):13, 1999. © 1999 International
Medical News Group.]
BETHESDA, MD. -- Needle-free jet injection devices can and should play a major role in solving the problems of needle-stick injuries and needlephobia in the United States, Dr. Bruce G. Weniger said at a meeting on needle-free injection sponsored by the Centers for Disease Control and Prevention.
Yet the needle-free jet injector industry is struggling to overcome significant obstacles in this country and abroad before these devices become widely accepted and used for administering drugs and especially for administering vaccines, said Dr. Weniger, assistant chief for vaccine development at the Centers for Disease Control and Prevention's National Immunization Program in Atlanta.
Most needle-free jet injectors use metal springs, compressed air, or CO2 gas to power the injection. The device's nozzle is held against the patient's skin at the injection site, and once activated, the device injects a fine stream of the vaccine or drug at a high pressure, penetrating into the skin.
The most common orifice size is 0.127 mm, whereas that of a 25-gauge needle is 1 mm, he noted.
Around the world, needle-free jet injectors have a small but established market among diabetic patients who do not share them with others.
In this country, about a dozen needle-free jet injectors have been licensed by the Food and Drug Administration and are on the market.
A few of these devices are being used in physicians' offices and clinics across the country.
One of the more popular needle-free jet injection devices used to deliver vaccines, according to Dr. Weniger, is the Biojector 2000.
This particular device is being used by 116 office-based physicians in the United States, according to a spokesperson for Bioject Inc., the Portland, Ore.-based manufacturer.
Currently, each manufacturer makes its own type of cartridge that holds the vaccine and is attached to the device before injection.
None of these cartridges are interchangeable, and that is a major limitation to their widespread use in physicians' offices in this country, said Dr. Weniger, who is promoting standard cartridge interfaces to solve the problem.
Third World countries would benefit greatly from needle-free injection technology, since many underdeveloped countries have a high rate of reusing disposable needles and have tremendous problems with safely disposing of them, Dr. Weniger said at the meeting, which was also sponsored by the World Health Organization and the Association of Needle-Free Injection Manufacturers.
But a key barrier is that current needle-free cartridges cost several times what developing countries now pay for conventional syringes and needles, the physician added.
However, Donatus Ekwueme, Ph.D., a CDC economist, presented an analysis showing that the hidden costs of iatrogenic disease from unsafe reuse of syringes in many African settings greatly exceeded the extra costs for needle-free injection devices.
Needle-free jet injectors can be categorized as either high-workload devices, which can inject more than 150 people per health care worker per hour and are designed for mass immunization campaigns, or low-workload devices, which can inject about 30 people per health care worker per hour and are intended for use in physicians' offices.
One major concern associated with the use of older devices that use the same metal nozzle for consecutive vaccinees is the potential for the transmission of infectious diseases from one patient to another, Dr. Weniger said.
The World Health Organization has issued a moratorium on the use of such high-workload devices, except in cases of an emergency, because of the fear of disease transmission in mass immunization campaigns.
In 1986, a high-workload jet injector was linked to the transmission of hepatitis B in at least 31 patients who were receiving injections of human chorionic gonadotropin via the device at a weight reduction clinic in Long Beach, Calif.
Experts are unsure of the exact transmission mechanism. One theory is that minute quantities of blood or tissue fluid are transferred to the nozzle of the device as it injects a product, and these are then injected along with the product to the next patient.
Manufacturers of newer devices have solved this problem by using disposable, single-use-only cartridges/nozzles in order to prevent transmission of infectious diseases.
The immune responses induced by needle-free injection devices tend to be equivalent to and often better than those by needle and syringe, Dr. Weniger said.
But immediate local reactions of erythema and hematoma and delayed soreness tend to occur more frequently with jet injectors than with needles and syringes. Injection sites from needle-free jet injections are also more likely to bleed than are injection sites from needles and syringes.
These devices were initially touted as being pain free or at least
as causing less pain than needles and syringes. But recent studies have
indicated that pain may be equivalent to or even greater than that associated
with needles, Dr. Weniger said.