Needle-Free Injection

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Overview

Needle-free jet injectors propel liquid or powder through a narrow orifice creating a high velocity stream that penetrates the skin and underlying tissue. The absence of needles, speed of delivery, relative ease of use, and demonstrated efficacy make these devices an attractive alternative mode of drug delivery.

A continuing issue with drug delivery using needle-free jet injectors (JI's) is repeatable delivery of a specific amount of active therapeutic to the target tissue. Commercial jet injectors powered by springs or compressed gases use a single jet velocity which affords little to no control over the pressure applied to the drug during the time course of the injection and
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could at high velocities result in shearing and loss of activity of larger therapeutic protein molecules. Furthermore, these devices are often loud and sometimes deemed painful [1][2]. Some pressure pulse shaping has been achieved by using variable gas orifices [3] and fast/slow pyrotechnic charges [4]. More recently, piezo-electric stack actuators [5] have been used to achieve controlled delivery but limited piston stroke constrains the volume of fluid delivered and scaling this technology is difficult.

We have developed a platform technology that uses a custom designed linear Lorentz-force motor to effect drug delivery. This technology is capable of accelerating drugs almost to the speed of sound (in air) in 2 to 10 ms dependent on the control scheme and can attain pressures as high as 100 MPa.

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Our actuator affords robust and precise control over coil position and thereby over injection depth and volume. Energy delivered to the actuator in an electrical form allows us to impose a time varying pressure profile (i.e. injection trajectory) on the drug volume during the course of the injection through the use of a monitored and servo-controlled amplifier. Injection trajectories are generated with two distinct phases of delivery: a brief high-speed pulse to breach the skin and deliver drug to the desired depth followed by a lower speed follow through period. During the initial phase of delivery, the coil is accelerated to a speed that achieves the desired jet velocity (Vjet), which is maintained for the user-defined time (Tjet), and then gently decelerated to the desired follow through speed (Vfollow). Vfollow is maintained until the coil position approaches the displacement at which the defined volume is realized.
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Drug delivered at this lower velocity reduces the potential for shearing and loss of stability while permitting absorption into the tissue.

Controlling the volume of drug delivered ensures that the relevant dose is delivered, potentially reduces the dose and cost per injection course, and increases the availability of drugs in limited supply. Controlling the depth of injection ensures delivery to the appropriate tissue layer regardless of body type and enables more accurate delivery of tissue-specific drugs.

Our technology affords a large mechanical displacement allowing flexible fluid handling with a wide volume range that includes bolus or rapid delivery of incremental volumes, the potential to deliver a wide variety of drugs, including lyophilized drugs, without reformulation, is bidirectional permitting easy loading, reloading, and reconstitution of drug, and can be coupled with sensors to provide quantitative measurement of qualitative variables such as mechanical properties of the skin. Delivery is both fast (<150 ms) and relatively silent (mean sound pressure of ~60 dB), attributes that have the potential to improve compliance.

Current research is directed toward evaluating the feasibility of using this technology to deliver vaccines and biotherapeutics to a variety of target tissues and organs.

Publications

  1. Taberner, A., Hogan, N.C., and Hunter, I.W. "Needle-free Jet Injection Using Real-time Controlled Linear Lorentz-force Actuators." Medical Engineering and Physics, 2012, doi:10.1016/j.medengphy.2011.12.01. [6]
  2. Hemond, B. D. Taberner, A., Hogan, C., Crane, B., and Hunter, I. W. "Development and performance of a controllable autoloading needle-free jet injector." Journal of Medical Devices 5 (1), pp. 015001-1-015001-7, 2011.[7]
  3. Hemond, B.D, D.M. Wendell, C. Hogan, A.J. Taberner, I.W. Hunter, "A Lorentz-Force Actuated Autoloading Needle-free Injector", Proc. 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society , 2006. [8]
  4. Hogan, N.C., B.D. Hemond, D.W. Wendall, A.J. Taberner, and I.W. Hunter Delivery of Active Collagenase to Skin Using a Lorentz-Force Actuated Needle-Free Injector, Proc. 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society , 2006. [9]
  5. Taberner, A.J., N.B. Ball, N.C. Hogan, I.W. Hunter A Portable Needle-free Jet Injector Based on a Custom High Power-density Voice-coil Actuator, Proc. 28th Conference of the IEEE Engineering in Medicine and Biology Society , 2006. [10]
  6. Wendell, D.M., B.D. Hemond, N.C. Hogan, A.J. Taberner, I.W. Hunter The Effect of Jet Parameters on Jet Injection, Proc. 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society , 2006. [11]
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