285 research outputs found
Drug Delivery Targeted to the Eye Using Microneedles
No full text2015 Fall Meeting of the NanoFANS Forum. Presented on October 29, 2015 from 11 a.m.-3 p.m. in the Marcus Nanotechnology Building (Rooms 1116-1118) on the Georgia Tech campus.NanoFANS Fall 2015 - Event Focus: Current Trends in OphthalmologyDr. Mark Prausnitz is a Professor of Chemical and Biomolecular Engineering at Georgia Tech.Runtime: 45:15 minute
Electroporation of tissue and cells for drug delivery applications
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1994.Includes bibliographical references (leaves 245-262).by Mark R. Prausnitz.Ph.D
Biophysical Methods of Drug Delivery
No full text2010 Fall
Meeting of the NANOFANS Forum. Presented on November 18, 2010 from 11 am-2 pm in the Marcus Nanotechnology Building (Rooms 1116-1118) on the Georgia Tech campus.The focus for this presentation was "Nanotechnology in Drug Delivery".Dr. Mark Prausnitz is a Professor
at the School of Chemical &
Biomolecular Engineering and
the Director of the Center for
Drug Design, Development and
Delivery at GaTech. A major
area of focus involves the use of
microneedle patches to apply
vaccines to the skin in a painless,
minimally invasive manner.Runtime: 41:02 minutesMany medical therapies would benefit from better control over drug transport into and within the body. Medicinal chemists often
control drug transport by changing drug structure in ways that alter its physicochemical properties. Pharmacists frequently control
drug transport by modifying the drug formulation by encapsulating drugs within carriers or adding excipients. These conventional
approaches accept the transport barriers imposed by the body as a given and work to design drugs and formulations that work
around those constraints. In our laboratory, we seek to remove those constraints by transiently breaking down transport barriers in
the body using biophysical mechanisms. The optimal extent and duration of barrier disruption depends on the nature of the barrier
and the desired application. The challenge of this approach is to achieve a balance between perturbing the barrier enough to achieve
drug delivery goals, but not so much as to cause lasting damage, safety concerns or pain. In some scenarios, we create
micrometer-scale pathways in tissue to target delivery to precise locations within tissues. Using microfabrication technology, we
have designed solid microneedle patches with coated or encapsulated drugs and vaccines for painless administration to the skin. We
showed that targeted influenza vaccination to the skin in this way induces more potent immune responses compared to conventional
intramuscular injection in mice. In addition, hollow microneedles that inject insulin in the skin of human diabetics show faster
pharmacokinetics and better blood glucose control compared subcutaneous infusion. We have also shown that hollow microneedles
enable injection into the suprachoroidal space of the eye, facilitating minimally invasive drug delivery targeted to the retina in rabbits
and pigs. In separate projects, we have used thermal ablation and microdermabrasion to selectively remove the outer permeability
barrier of the skin "the stratum corneum" and thereby allow absorption of macromolecules. In other scenarios, we create
nanometer-scale holes in cell membranes to drive molecules into tissues and cells more effectively. One approach involves
electroporation, which we employ to drive genetic material into cells for gene therapy and DNA vaccination and to increase
permeability of epithelial barriers to increase drug absorption. We also study the use of ultrasound under conditions that generate
cavitational bubble activity, which can be harnessed to increase cell membrane permeability for uptake of macromolecules. More
recently, we have employed laser-activated nanoparticles that similarly open cell membranes for drug uptake by a mechanism
believed to involve cavitation as well. Overall, we seek to enable and increase the efficacy of pharmaceutical therapies by transiently
disrupting transport barriers in the body at the nanometer and micrometer lengthscales in order to increase uptake and target
delivery of drugs, proteins, DNA and vaccines
Transdermal drug delivery.
No full text1261 Perhaps the greatest challenge for transdermal delivery is that only a limited number of drugs are amenable to administration by this route. With current delivery methods, successful transdermal drugs have molecular masses that are only up to a few hundred Daltons, exhibit octanolwater partition coefficients that heavily favor lipids and require doses of milligrams per day or less Another area of great interest is the delivery of vaccines 7 . In addition to avoiding hypodermic needles, transdermal vaccine delivery could improve immune responses by targeting delivery to immunogenic Langerhans cells in the skin (Box 1). Given the external placement and patient control over patches, it might also be possible to develop modulated or pulsatile delivery, which could involve feedback control. Indeed, an analgesic patch was recently approved in the United States that uses patient-regulated delivery of fentanyl modulated by electricity to control pain (iontophoresis) 8 , which has also been launched in Europe. Finally, there is the possibility of not only delivering drugs, but also extracting molecules (analytes) through the skin 9 . This has already been achieved for glucose monitoring by extracting interstitial fluid using electrical means and is in clinical trials using other approaches, such as ultrasound. From a global perspective, we propose that advances in transdermal delivery systems can be categorized as undergoing three generations of development from the first generation of systems that produced many of today's patches by judicious selection of drugs that can cross the skin at therapeutic rates with little or no enhancement; through the second generation that has yielded additional advances for small-molecule delivery by increasing skin permeability and driving forces for transdermal transport; to the third generation that will enable transdermal delivery of small-molecule drugs, macromolecules (including proteins and DNA) and virus-based and other vaccines through targeted permeabilization of the skin's stratum corneum. In this review, we describe the transdermal delivery methods in each generation. We then comment on their current and future potential in medicine. Transdermal delivery represents an attractive alternative to oral delivery of drugs and is poised to provide an alternative to hypodermic injection, too 1-4 . For thousands of years, people have placed substances on the skin for therapeutic effects and, in the modern era, a variety of topical formulations have been developed to treat local medical conditions. The first transdermal system for systemic delivery-a three-day patch that delivers scopolamine to treat motion sickness-was approved for use in the United States in 1979. A decade later, nicotine patches became the first transdermal blockbuster, raising the profile of transdermal delivery in medicine and for the public in general. Today, there are 19 transdermal delivery systems for such drugs as estradiol, fentanyl, lidocaine and testosterone; combination patches containing more than one drug for contraception and hormone replacement; and iontophoretic and ultrasonic delivery systems for analgesia Transdermal delivery has a variety of advantages compared with the oral route. In particular, it is used when there is a significant first-pass effect of the liver that can prematurely metabolize drugs. Transdermal delivery also has advantages over hypodermic injections, which are painful, generate dangerous medical waste and pose the risk of disease transmission by needle re-use, especially in developing countries 5 . In addition, transdermal systems are noninvasive and can be self-administered. They can provide release for long periods of time (up to one week). They also improve patient compliance and the systems are generally inexpensive. Transdermal drug delivery Mark R Prausnitz 1 & Robert Langer 2 Transdermal drug delivery has made an important contribution to medical practice, but has yet to fully achieve its potential as an alternative to oral delivery and hypodermic injections. First-generation transdermal delivery systems have continued their steady increase in clinical use for delivery of small, lipophilic, low-dose drugs. Second-generation delivery systems using chemical enhancers, noncavitational ultrasound and iontophoresis have also resulted in clinical products; the ability of iontophoresis to control delivery rates in real time provides added functionality. Third-generation delivery systems target their effects to skin's barrier layer of stratum corneum using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound. Microneedles and thermal ablation are currently progressing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. Using these novel second-and third-generation enhancement strategies, transdermal delivery is poised to significantly increase its impact on medicine
Microneedle Drug Delivery Device
No full textSimple microneedle devices for delivery of drugs across or into biological tissue are provided, which permit drug delivery at clinically relevant rates across or into skin or other tissue barriers, with minimal or no damage, pain, or irritation to the tissue. The devices include a substrate to which a plurality of hollow microneedles are attached or integrated, and at least one reservoir, containing the drug, selectably in communication with the microneedles, wherein the volume or amount of drug to be delivered can be selectively altered. The reservoir can be formed of a deformable, preferably elastic, material. The device typically includes a means, such as a plunger, for compressing the reservoir to drive the drug from the reservoir through the microneedles. In one embodiment, the reservoir is a syringe or pump connected to the substrate.Georgia Tech Research Corporatio
Microneedle Drug Delivery Device
No full textSimple microneedle devices for delivery of drugs across or into biological tissue are provided, which permit drug delivery at clinically relevant rates across or into skin or other tissue barriers, with minimal or no damage, pain, or irritation to the tissue. The devices include a substrate to which a plurality of hollow microneedles are attached or integrated, and at least one reservoir, containing the drug, selectably in communication with the microneedles, wherein the volume or amount of drug to be delivered can be selectively altered. The reservoir can be formed of a deformable, preferably elastic, material. The device typically includes a means, such as a plunger, for compressing the reservoir to drive the drug from the reservoir through the microneedles, In one embodiment, the reservoir is a syringe or pump connected to the substrate.Georgia Tech Research Corporatio
Method Of Applying Acoustic Energy Effective To Alter Transport Or Cell Viability
No full textA method for reversibly, or irreversibly, altering the permeability of cells, tissues or other biological barriers, to molecules to be transported into or through these materials, through the application of acoustic energy, is enhanced by applying the ultrasound in combination with devices for monitoring and/or implementing feedback controls. The acoustic energy is applied directly or indirectly to the cells or tissue whose permeability is to be altered, at a frequency and intensity appropriate to alter the permeability to achieve the desired effect, such as the transport of endogenous or exogenous molecules and/or fluid, for drug delivery, measurement of analyte, removal of fluid, alteration of cell or tissue viability or alteration of structure of materials such as kidney or gall bladder stones. In the preferred embodiment, the method includes measuring the strength of the acoustic field applied to the cell or tissue at the applied frequency or other frequencies, and using the acoustic measurement to modify continued or subsequent application of acoustic energy to the cell or tissue. In another preferred embodiment, the method further includes simultaneously, previously, or subsequently exposing the cell or tissue to the chemical or biological agent to be transported into or across the cell or tissue. In another preferred application, the method includes removing biological fluid or molecules from the cells or tissue simultaneously, previously or subsequently to the application of acoustic energy and, optionally, assaying the biological fluid or molecules.Georgia Tech Research Corporatio
Devices And Methods For Enhanced Microneedle Penetration Of Biological Barriers
No full textMicroneedle devices and methods of use thereof are provided for the enhanced transport of molecules, including drugs and biological molecules, across tissue by improving the interaction of microneedles and a deformable, elastic biological barrier, such as human skin. The devices and methods act to (1) limit the elasticity, (2) adapt to the elasticity, (3) utilize alternate ways of creating the holes for the microneedles to penetrate the biological barrier, other than the simply direct pressure of the microneedle substrate to the barrier surface, or (4) any combination of these methods. In preferred embodiments for limiting the elasticity of skin, the microneedle device includes features suitable for stretching, pulling, or pinching the skin to present a more rigid, less deformable, surface in the area to which the microneedles are applied (i.e. penetrate). In a preferred embodiments for adapting the device to the elasticity of skin, the device comprising one or more extensions interposed between the substrate and the base end of at least a portion of the microneedles.Georgia Tech Research Corporatio
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