Drug Delivery by Jet Injectors Conventional needles offer the primary method for the delivery of macromolecular
drugs. However, patient compliance with needle injection is low, especially for chronic
prescriptions. To minimize pain and discomfort of injections, jet injectors were proposed
several decades ago, which produce a high velocity jet (d ~150 mm, v > 100 m/s) that
penetrates into the skin. Jet injections have been marketed for mass immunization and
insulin delivery and recently, jet injectors have also been utilized for gene delivery.
However, occasional pain and bruising still limit the widespread use of jet injectors. Our research is focused on studying the fundamental mechanisms of drug delivery
by jet injection in order to identify design parameters for a new painless generation of jet
injectors. Specifically, we are investigating the mechanisms of penetration and dispersion
of the jet into skin. We continue to assess the mechanisms through which jet-induced
stresses lead to skin rupture and subsequent jet entry into the skin. Experimental studies are being conducted to determine the dependence of jet penetration and dispersion on important jet and material parameters. Our experimental analysis includes characterization of jets (using pressure sensors and high-speed imaging), mechanical testing of skin and other model materials (universal mechanical tester, durometer), measurement of jet-induced erosion (microscopy), determination of jet penetration into skin (radiolabeled drugs), and characterization of jet dispersion (digital image analysis). By using theories of turbulent jets and pressure-driven flow in poro-elastic media we are developing a model of drug delivery by jet injection. Continued research on jet injection is expected to yield a sophisticated understanding of the interactions of liquid jets and skin which will allow the manipulation of identified parameters for the development of a small, painless, jet injector that improves patient compliance. |