Jet injectors

Therapeutic ultrasound has been found to first expand and then collapse air huhhles in the stratum corneum (the process of cavitation). Cavitation tends to liquefy the solid fats and allows molecules such as insulin to pass through the skin at levels which in diabetic rats causes blood sugar lowering. The permeability of the skin was found to increase as the frequency of ultrasound decreased and no long-term damage was caused. 

Rguie 9.31 Average % delivery of mannitol by jet injection through o 152 nm diameter nozzle into human ( ) and porcine ( ] skin. The error bars shown ore one standard deviation (n = 5-19 for each human skin data point). The magnitude of the delivery into human skin is higher than into porcine skin. 

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Strahl-antrieb, m. jet propulsion, -apparat, m. jet apparatus (as steam-jet injector, pump, or blower), -asbest, m. plumose asbestos, -baryt, m. radiated barite, Bologna stone, -blende, /. a variety of sphalerite. -dUse, /. jet nozzle. 

Haensler, J., Verdelet, C., Sanchez, V., Girerd-Chambaz, Y., Bonnin, A., Trannoy, E., Krishnan, S. and Meulien, P. (1999) Intradermal DNA immunization by using jet-injectors in mice and monkeys. Vaccine, 17, 628-638. 

Williams, J., Fox-Ley va, L., Christensen, C., Fisher, D., Schlicting, E., Snowball, M. etal. (2000) Hepatitis A vaccine administration comparison between jet-injector and needle injection. Vaccine, 18,1939-1943. 

When gas molecules under high pressure are allowed to escape and expand, they release kinetic energy. This energy has been harnessed to benefit human health by powering high-pressure injectors, better known as jet injectors. 

Today jet injectors use a tank of compressed gas and an automatic vaccine dispenser that works through a pistol-like injector. When triggered, the new device releases a measured dose of vaccine into a sterile chamber and a small volume of gas through a hose. As the compressed gas expands, it forces the vaccine at high velocity through the injector s nozzle. 

In 1958, Higson led a team that inoculated about 90 000 people in Asia and Africa against polio, typhoid, and cholera using the Hypospray. In 1965, the United Nation s World Health Organization used the jet injector. The organization freeze-dried vaccines for its successful worldwide smallpox eradication program. For its key role in eliminating smallpox from the list of human diseases, the jet injector earned a new name—the "Peace Pistol."... 

Baker, A.B. Sanders, J.E. Fluid mechanics analysis of a spring-loaded jet injector. IEEE Trans. Biomed. Engineer 1999, 46, 235-242. 

Kerum, G. Profozic, V. Granic, M. Skrabalo, Z. Blood glucose and free insulin levels after the administration of insulin by conventional syringe or jet injector in insulin treated type 2 diabetics. Horm. Metab. Res. 1987, 19, 422-425. 

Halle, J.-P. Lambert, J. Lindmayer, I. Menassa, K. Coutu, F. Moghrabi, A. Legendre, L. Legault, C. Lalumiere, G. Twice daily mixed regular and NPH insulin injections with new jet injector versus conventional syringes pharmacokinetics of insulin absorption. Diabetes Care 1986, 9, 279-282. 

Samo, M.J. Blase, E. Galindo, N. Ramirez, R. Schirmer, C.L. Trujillo-Juarez, D.E. Clinical immunogenicity of measles, mumps and rubella vaccine delivered by the Injex jet injector comparison with standard syringe injection. Pediatr. Infect. Dis. J. 2000, 19, 839-842. 

The first outbreak of a disease in which a jet injector was imphcated as the vehicle of transmission has been reported. Thirty-one attendees at a weight-reduction clinic in Southern California experienced hepatitis B after daily parenteral injections of human chorionic gonadotrophin given by jet injectors transmission appeared to have resulted from the multiple repeated jet injections (85). WHO and UNICEF have stated in their Guidehnes for selecting injection equipment for the Expanded Program on Immunization that the use of jet injectors should be restricted to circumstances in which reusable or disposable equipment is not feasible because of the large number of persons to be immunized within a short period of time (83). 

Condensers.—From a thermal standpoint, condensers may be classified as mixing (horizontal independent jet, injector or barometric) and non-mixing (surface) types.. The equations above given for feed-water heaters will apply as an error on the safe side, x may be taken as 1.0. The value of ti is determined by the available supply of cooling water in this latitude under summer conditions, it is rarely below 70°. That of to will be in surface condensers 6 to 10° below tj and that of t2 the same amount below U- The value of to determines the best possible vacuum. Orrok gives k = SfiOr VF, for clean copper tubes, where V = water velocity in tubes, feet per second, r = ratio of partial pressure of steam to total pressure in the condenser. If condensers and vacuum pumps are tight, r == 0.95. 

More investigation is needed into transcutaneous delivery. Needle-free systems such as jet injectors , which force liquid or powdered drug though the skin by the means of compressed gas, could be an alternative if discomfort (bruising) is minimised. The microneedle system of delivery also seems very promising. Compared with hypodermic needles, microneedles do not significantly stimulate nerve endings and are thus well tolerated. 

Jet injectors may also be combined with monolith reactors. Monoliths are usually tube reactors with channeled flow. The reaction occurs at the gas-liquid interface as well as on the channel wall, which are usually catalytic or coated with catalytic material. Monoliths can be made into vertical (similar to bubble column) or horizontal tubes, airlift devices (whereby the riser would a monolith), or even into a mechanically stirred device. Usually, however, monoliths are designed like bubble columns or airhft reactors (Broekhuis et al., 2001). 

There are different devices conunerciaUy available for needle-free injectirai. Commonly jet injectors produce a high-velocity jet of medicine that penetrate the skin. Medicines and vaccines can be administered either intramuscularly or subcutaneously by means of a narrow, high velocity fluid jet that penetrates the skin. The gas-forced needle-free injection systems are typically made up of three components including an injection device, a disposable needle free syringe and a gas cartridge. 

Jet injectors deliver insulin transcutaneously by an air-jet mechanism. The insulin solution or suspension is forced at high pressure through a fine nozzle, penetrates the skin without a needle, and creates a multitude of small depots. The dispersion of insulin deposited in the tissue explains the more rapid absorption of both rapid- and retarded-acting preparations (Taylor et al, 1981 Malone eta/., 1986 Houtzagerse/a/., 1988). Jet injection seems to affect the action profile of NPH insulin more markedly than that of the Lente t e insulins (Houtzagers et al, 1988). These devices are not painless and, in a European study, not well accepted by patients irrespective of the presence or absence of needle phobia (Houtzagers etal, 1988). However, in a more recent American study, the majority of patients preferred to take insulin by jet injector compared to needle injection (Denne et al, 1992). Jet injection has been found to be associated with a diminished antibody... 

Denne, J. R., Andrews, K. L., Lees, D. V., and Mook, W., 1992, A survey ofpatient preference for insulin jet injectors versus needle and syringe. Diabetes Educ. 18 223-227. 

Skeletal Muscle DNA. Hypertonic sucrose, bupivicaine, Naja nagricollis cardiotoxin, gene gun, jet injector... 

Lastly, droplet distribution curves and droplet size characteristic measurements were made for each of the sprays. Figure 15.13 shows the droplet size characteristics for the pressure swirl injector and Fig. 15.14 shows the droplet size characteristics for the liquid jet injector. The droplet size distribution is shown in both a cumulative and normalized sense. The cumulative volume fraction is used to determine DvO.l, DvO.5, and DvO.9 measurements. The calculated values for DIO, D31, and SMD are also shown on each plot. In general, the pressure swirl injector analyzed had a tighter distribution of injected droplets. The tighter distribution means that there are fewer larger droplets measured, which create smaller values for all of the key droplet characteristics, measured (D31, DIO, DvO.l, Dv05, DvO.9, and D32). 

Fig. 15.14 Spray quality comparison—droplet size (liquid jet injector)...

Figure 7.8 Microreactor channel design with droplet jet injector, (a) Channel schematic showing dimensions, (b) Optical micrograph of droplet injection cross, (c), (d) Cross-sectional view of the channel, (e) Side view of the channel. (Reproduced form Ref [99].)...

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