451
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Mitragotri S, Coleman M, Kost J, Langer R. Transdermal extraction of analytes using low-frequency ultrasound. Pharm Res 2000; 17:466-70. [PMID: 10870992 DOI: 10.1023/a:1007537222591] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Transdermal extraction of clinically relevant analytes offers a potentially non-invasive method of diagnostics. However, development of such a method is limited by the low skin permeability. In this paper, we report a potential method for non-invasive diagnostics based on ultrasonic skin permeabilization and subsequent extraction of interstitial fluid (ISF) across the skin. METHODS In vivo experiments were performed using Sprague Dawley rats to assess ultrasound-induced skin permeabilization and subsequent extraction of various analytes. Serum and ISF concentrations of various analytes were measured. RESULTS Application of low-frequency ultrasound rapidly increased skin permeability. Skin remained in a state of high permeability for at least three hours. During this period, application of vacuum extracted ISF across rat skin in vivo at a rate of 25.7 microl/cm2/hr. We measured concentrations of various analytes including glucose, albumin, calcium, urea, triglycerides, lactate, and dextran in transdermally extracted fluid. The composition of the fluid extracted transdermally is similar to that of ISF. CONCLUSIONS Application of low-frequency ultrasound allows skin permeabilization and extraction of ISF across the skin.
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Affiliation(s)
- S Mitragotri
- Department of Chemical Engineering, University of California, Santa Barbara 93106, USA.
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452
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Kost J, Mitragotri S, Gabbay RA, Pishko M, Langer R. Transdermal monitoring of glucose and other analytes using ultrasound. Nat Med 2000; 6:347-50. [PMID: 10700240 DOI: 10.1038/73213] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J Kost
- Department of Chemical Engineering, Ben-Gurion University, Beer-Sheva, 84105 Israel.
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453
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Abstract
Macromolecules comprise a growing group of new drugs with great clinical promise. To date, the therapeutic application of these drugs has been limited, because they are effective only when administered parenterally. Unfortunately, macromolecular drugs are not absorbed following nonparenteral dosing, because the mechanisms of the human body are designed to degrade and/or exclude them. To overcome the numerous obstacles to the noninvasive delivery of these drugs, various approaches are under investigation including the use of delivery agents to promote drug absorption. This review provides a summary of the novel approaches currently in progress in the areas of transdermal, transmucosal, and oral delivery of macromolecular drugs facilitated by delivery agents. We review our own novel work in this area in some detail, including the methods developed for the synthesis of the delivery agents, in vitro screening techniques developed to select compounds for in vivo testing, and the results of in vivo screening in both rats and primates, including preliminary safety and efficacy studies. Finally, the results of Phase I clinical studies showing the oral delivery of heparin are presented.
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Affiliation(s)
- A Leone-Bay
- Emisphere Technologies, Inc., Tarrytown, NY 10591, USA
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454
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Frenkel V, Kimmel E, Iger Y. Ultrasound-induced intercellular space widening in fish epidermis. ULTRASOUND IN MEDICINE & BIOLOGY 2000; 26:473-480. [PMID: 10773379 DOI: 10.1016/s0301-5629(99)00164-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Transmission electron microscopy was employed to determine the effects of therapeutic ultrasound (US) (I(sata) < or =2.2 W cm(-2), 3 MHz), sonicated at different angles and durations, on the external epithelia of fish skin. Sonication at 1.7 W cm(-2) (90 s), where the ultrasonic beam was perpendicular to the skin surface, produced minor intercellular space widening (ICSW), as well as the disruption of desmosomes connecting between the cells. Increasing the intensity to 2.2 W cm(-2) increased ICSW, the extent of which was positively correlated to the duration of exposure (30 to 90 s). Perpendicular sonication produced ICSW, almost exclusively between cells of the two outermost cell layers, parallel to the skin surface. Sonicating at 45 degrees (2.2 W cm(-2), 90 s) produced ICSW in deeper cell layers in the tissues, in which the spaces were at seemingly random orientations. Mucous cells and macrophages were also found to be damaged, as were apoptotic epidermal cells. The suggested mechanism for ICSW is the formation of transverse (shear) waves at the interface between the aquatic medium and the skin surface. The waves, which are damped out within a few cell layers, give rise to shear stresses that, in turn, cause strains that act to separate between cells and damage some of the relatively weaker cells.
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Affiliation(s)
- V Frenkel
- Agricultural Engineering Department, Technion, Haifa, Israel
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455
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Langer R. Biomaterials in drug delivery and tissue engineering: one laboratory's experience. Acc Chem Res 2000; 33:94-101. [PMID: 10673317 DOI: 10.1021/ar9800993] [Citation(s) in RCA: 554] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This Account reviews our laboratory's research in biomaterials. In one area, drug delivery, we discuss the development of materials that are capable of releasing macromolecules such as proteins and peptides, intelligent delivery systems based on magnetism or microchip technology, new degradable materials such as polyanhydrides, and noninvasive approaches for delivering molecules through the skin and lungs. A second area, tissue engineering, is also discussed. New polymer systems for creating cartilage, blood vessels, nerves, and other tissues are examined.
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Affiliation(s)
- R Langer
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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456
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Stoll BR, Batycky RP, Leipold HR, Milstein S, Edwards DA. A theory of molecular absorption from the small intestine. Chem Eng Sci 2000. [DOI: 10.1016/s0009-2509(99)00308-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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457
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Mitragotri S, Farrell J, Tang H, Terahara T, Kost J, Langer R. Determination of threshold energy dose for ultrasound-induced transdermal drug transport. J Control Release 2000; 63:41-52. [PMID: 10640579 DOI: 10.1016/s0168-3659(99)00178-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Low-frequency (20 kHz) ultrasound has been shown to enhance transdermal transport of drugs, a phenomenon referred to as sonophoresis. In this paper, we report the threshold energy dose for ultrasound-induced transdermal drug transport. The threshold was determined by in vitro measurements of the dependence of sonophoretic enhancement on ultrasound parameters, including intensity, duty cycle, and exposure time. While the enhancement varies linearly with ultrasound intensity and exposure times, it is independent of the duty cycle in the range of parameters studied. The enhancement is also directly proportional to the ultrasound energy density once the threshold value is crossed. For full thickness pig skin, the threshold value is about 222 J/cm(2). The overall dependence of transport enhancement on ultrasound parameters is similar to that of cavitation measured in a model system, pitting of aluminum foil. Specifically, the extent of pitting is proportional to ultrasound intensity and exposure time and is independent of duty cycle. Furthermore, the extent of pitting is also proportional to the ultrasound energy density. The similarity between the parametric dependence of transport enhancement and cavitation is consistent with previous findings that cavitation plays the dominant role in sonophoresis.
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Affiliation(s)
- S Mitragotri
- Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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458
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Abstract
THE SKIN ACTS AS A VITAL BARRIER between an individual and the environment by limiting water loss and by protecting against the entry of harmful substances. Various material can pass through the skin barrier, a process called percutaneous absorption. Although the skin’s permeability can lead to harmful effects, it can be beneficial in making the skin a possible route for the delivery of therapeutic drugs. Differences between adult and neonatal skin, especially preterm skin, expose the neonate to a greater potential for percutaneous absorption.1 Neonatal nurses need to be familiar with the characteristics of newborn skin, principles for maintaining skin integrity, and the risks and benefits of percutaneous absorption.
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Affiliation(s)
- M M Benis
- Fletcher Allen Health Care, University of Vermont, Burlington, USA
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459
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Fang J, Fang C, Sung KC, Chen H. Effect of low frequency ultrasound on the in vitro percutaneous absorption of clobetasol 17-propionate. Int J Pharm 1999; 191:33-42. [PMID: 10556738 DOI: 10.1016/s0378-5173(99)00230-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of low frequency ultrasound (20 kHz) on the permeation of clobetasol 17-propionate (CP) through skin (sonophoresis) was studied. The ultrasound was applied at either continuous or discontinuous modes and at different intensities. The results showed that low frequency ultrasound significantly enhanced the permeability of CP across hairless mouse skin in vitro. Delivering the same amount of ultrasonic energy in different modes of application markedly influenced the flux and skin residual of CP. The on/off discontinuous ultrasound had greater enhancement on CP permeation than the continuous ultrasound. The results of skin histopathology and permeation experiment using various membranes demonstrate that both disordering of stratum corneum and convective flow resulted from the cavitation effect were responsible for sonophoretic enhancement of CP. The permeation of CP through hair follicles and sweat ducts was susceptible to the application of ultrasound.
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Affiliation(s)
- J Fang
- Graduate Institute of Pharmaceutical Sciences, Taipei Medical College, 250 Wu-Hsing Street, Taipei, Taiwan.
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460
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Lee S, Kollias N, McAuliffe DJ, Flotte TJ, Doukas AG. Topical drug delivery in humans with a single photomechanical wave. Pharm Res 1999; 16:1717-21. [PMID: 10571277 DOI: 10.1023/a:1018954015441] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Assess the feasibility of in vivo topical drug delivery in humans with a single photomechanical wave. METHODS Photomechanical waves were generated with a 23 nsec Q-switched ruby laser. In vivo fluorescence spectroscopy was used as an elegant non-invasive assay of transport of 5-aminolevulinic acid into the skin following the application of a single photomechanical wave. RESULTS The barrier function of the human stratum corneum in vivo may be modulated by a single (110 nsec) photomechanical compression wave without adversely affecting the viability and structure of the epidermis and dermis. Furthermore, the stratum corneum barrier always recovers within minutes following a photomechanical wave. The application of the photomechanical wave did not cause any pain. The dose delivered across the stratum corneum depends on the peak pressure and has a threshold at approximately 350 bar. A 30% increase in peak pressure, produced a 680% increase in the amount delivered. CONCLUSIONS Photomechanical waves may have important implications for transcutaneous drug delivery.
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Affiliation(s)
- S Lee
- Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Department of Dermatology, Harvard Medical School, Boston 02114, USA.
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461
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Affiliation(s)
- R Langer
- MIT, 77 Mass. Ave., E25-342, Cambridge, MA 02139, USA
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462
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Frenkel V, Kimmel E, Iger Y. Ultrasound-induced cavitation damage to external epithelia of fish skin. ULTRASOUND IN MEDICINE & BIOLOGY 1999; 25:1295-303. [PMID: 10576272 DOI: 10.1016/s0301-5629(99)00069-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Transmission electron microscopy was used to show the effects of therapeutic ultrasound (< or = 1.0 W/cm2, 1 MHz) on the external epithelia of fish skin. Exposures of up to 90 s produced damage to 5 to 6 of the outermost layers. Negligible temperature elevations and lack of damage observed when using degassed water indicated that the effects were due to cavitation. The minimal intensity was determined for inducing cellular damage, where the extent and depth of damage to the tissues was correlated to the exposure duration. The results may be interpreted as a damage front, advancing slowly from the outer cells inward, presumably in association with the slow replacement of the perforated cell contents with the surrounding water. This study illustrates that a controlled level of microdamage may be induced to the outer layers of the tissues.
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Affiliation(s)
- V Frenkel
- Agricultural Engineering Department, Technion, Haifa, Israel
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463
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Abstract
As the millennium approaches nurses are challenged to reflect on the evolving role of technology on the profession. A preview of the technologies coming to the clinical arena in the not-so-distant future is provided. Eight guidelines for wise technology integration are offered to assist providers in appropriately using technology while preserving humanity in an increasingly high-technology world.
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Affiliation(s)
- M Buus-Frank
- Children's Hospital at Dartmouth and Southern New Hampshire Medical Center, Nashua, NH, USA
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464
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Ramkissoon-Ganorkar C, Liu F, Baudys M, Kim SW. Modulating insulin-release profile from pH/thermosensitive polymeric beads through polymer molecular weight. J Control Release 1999; 59:287-98. [PMID: 10332061 DOI: 10.1016/s0168-3659(99)00006-1] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Stimuli-sensitive statistical terpolymers of N-isopropylacrylamide (NIPAAm) (temperature-sensitive), butyl methacrylate (BMA) and acrylic acid (AA) (pH-sensitive) of various molecular weight (MW) with NIPAAm/BMA/AA feed mol ratio of 85/5/10 were used to modulate release of insulin, a model protein drug, from pH/thermosensitive polymeric beads. Protein drug loading from an aqueous medium into the beads was achieved by preparing a 7 or 10% (w/v) polymer solution with 0.2% (w/v) insulin at low pH and below the lower critical solution temperature (LCST) of the polymer (pH 2.0 and 4 degrees C), and then dropping the solution into an oil bath above the LCST of the solution (35 degrees C). This loading procedure maintained protein stability while achieving high loading efficiency, between 90 and 95% in the beads. Insulin-release studies from beads prepared from terpolymers of the same composition but increasing MW were performed at pH 2.0 and 7.4, at 37 degrees C. It was observed that there was negligible loss of insulin at pH 2.0 from the beads, indicating no burst effect. At pH 7.4, insulin release was seen from all the beads and the release rate was a function of the MW of the polymer. The low MW polymeric beads eroded, dissolved and released most of the insulin within 2 h at pH 7.4 and 37 degrees C, the intermediate MW polymeric beads swelled slightly, dissolved and released most of the insulin within 4 h, whereas the high MW polymeric beads swelled slowly and gradually released the loaded insulin over a period of 8 h. Thus, the release of protein from the low MW polymeric beads is controlled by the rate of dissolution of the polymer, whereas the release from the high MW polymeric beads is controlled by swelling of the beads and drug diffusion. Studies using fluorescein-labeled insulin revealed that insulin was uniformly distributed in the beads regardless of polymer MW. The loaded and released insulin were fully bioactive. Based on the described results, the low MW polymeric beads may be used for immediate delivery of protein drugs in the duodenum, the intermediate MW polymeric beads may be used for lower small intestine targeting, while the high MW polymeric beads may be used to target protein drugs predominantly to the colon.
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Affiliation(s)
- C Ramkissoon-Ganorkar
- Department of Pharmaceutics and Pharmaceutical Chemistry, Center for Controlled Chemical Delivery, University of Utah, Salt Lake City, UT 84112, USA
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465
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Abstract
Therapeutic modalities are useful adjuncts in the rehabilitation of many patients commonly seen by hand surgeons. Therapeutic heat, cold, electrical stimulation, and laser and magnetic field treatments are evaluated for their respective mechanisms of action, indications, contraindications, and clinical results. The majority of therapeutic modalities have been extensively investigated and relevant basic science and randomized well-controlled clinical studies addressing the efficacy of therapeutic modalities are emphasized.
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Affiliation(s)
- J H Bissell
- Department of Physical Medicine and Rehabilitation, Centura Rehabilitation, St Mary Corwin Medical Center, Pueblo, CO 81004, USA
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466
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Misík V, Riesz P. EPR characterization of free radical intermediates formed during ultrasound exposure of cell culture media. Free Radic Biol Med 1999; 26:936-43. [PMID: 10232837 DOI: 10.1016/s0891-5849(98)00282-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Free radicals and/or hydrogen peroxide produced by exposure of cells to ultrasound are potentially cytotoxic and mutagenic. The formation and type of free radical species can be substantially modulated by the chemical composition of the media in which the ultrasound exposures of cells are carried out. In the current study, we examined the free radical intermediates formed during ultrasound exposure of a typical cell culture medium (RPMI-1640); the dominant free radicals that were identified by spin trapping were derived from the hydrophobic amino acids Trp, Leu, and Phe, and were formed by hydrogen abstraction from these amino acids. Compared to exposures in phosphate-buffered saline, the yield of *OH radicals and H2O2 was significantly reduced in the cell culture medium, glucose (the main organic component in the medium), and the hydrophobic amino acids (Trp, Phe, Tyr, Leu, Val, Met) being chiefly responsible for this effect. In contrast, other nonhydrophobic amino acids did not contribute significantly to the *OH or H2O2 decrease. These findings are consistent with the accumulation of hydrophobic solutes at the liquid-gas interface of the collapsing cavitation bubbles resulting in increased efficiency of radical scavenging.
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Affiliation(s)
- V Misík
- Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1002, USA
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467
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Abstract
The application of electrical high voltage pulses has been shown to greatly enhance the transdermal transport of water-soluble compounds. The resistance of the skins most important barrier, the stratum corneum, drops within less than 1 µs by orders of magnitude. This effect is attributed to electroporation, a nonthermic phenomena known to occur in phospholipid double layers. The striking difference between the stratum corneum lipid layers and the usually investigated phospholipid systems is the phase transition temperature. While lipid layers used for electroporation experiments are in liquid crystal phase above the phase transition temperature, the stratum corneum lipids (phase transition at approximately 70 degrees C) form a rigid quasi-crystalline membrane at room temperature.After the electrical stimulus a recovery of the passive flux was found making high voltage pulsing a suitable tool for controlling transdermal drug delivery. By ordinary light microscopy no dramatic changes in skin structure were found supporting the thesis of electroporation. However the microstructure shows clearly persistent structural changes. Recently the involvement of Joule heating due to the electric stimulus was shown as an important factor for skin permeabilization and molecular transport.
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468
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Abstract
Transdermal drug delivery has many potential advantages, but the skin's poorly-permeable stratum corneum blocks delivery of most drugs at therapeutic levels. Short high-voltage pulses have been used to electroporate the skin's lipid bilayer barriers and thereby deliver compounds at rates increased by as much as four orders of magnitude. Evidence that the observed flux enhancement is due to physical alteration of the skin by electroporation, as opposed to only providing an iontophoretic driving force, is supported by a number of different transport, electrical and microscopy studies. Practical applications of electroporation's unique effects on skin are motivated by large flux increases for many different compounds, rapidly responsive delivery profiles, and efficient use of skin area and electrical charge. Greater enhancement can be achieved by combining skin electroporation with iontophoresis, ultrasound, and macromolecules. Sensation due to electroporation can be avoided by using appropriate electrical protocols and electrode design. To develop skin electroporation as a successful transdermal drug delivery technology, the strong set of existing in vitro mechanistic studies must be supplemented with studies addressing in vivo/clinical issues and device design.
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469
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Emilien G, Maloteaux JM, Ponchon M. Pharmacological management of diabetes: recent progress and future perspective in daily drug treatment. Pharmacol Ther 1999; 81:37-51. [PMID: 10051177 DOI: 10.1016/s0163-7258(98)00034-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Glycaemic control in Type 1 diabetes has been proven efficient in preventing microvascular and neurological complications. The assumption that good control of hyperglycaemia may also have significant impact on alleviation of complications in Type 2 diabetes has gained growing support in recent years. Measures such as body weight reduction and exercise improve the metabolic defects, but pharmacological therapy is most frequently used. The sulphonylureas stimulate insulin secretion. Metformin and troglitazone increase glucose disposal and decrease hepatic glucose output without causing hypoglycaemia. Acarbose helps to spread the dietary carbohydrate challenge to endogenous insulin over time. These pharmacological treatments can improve blood glucose regulation in Type 2 diabetes patients. However, the key to strict glycaemic control with use of exogenous insulin lies in the creation of delivery methods that emulate physiologic insulin secretion. Insulin lispro, a recombinant insulin analogue, is identical to human insulin except for the transposition of proline and lysine at positions 28 and 29 in the C-terminus of the B chain. Evidence suggests that patients perceive their quality of life to be improved with insulin lispro when compared with regular human insulin, and that satisfaction with treatment is greater with the insulin analogue. Numerous new pharmacological approaches are under active investigation, with the aim of promoting insulin secretion, improving the action of insulin, or slowing carbohydrate absorption. With respect to continuous subcutaneous insulin infusion therapy and implantable pumps, despite that this approach is not widely utilised, it appears to bring us as close to achieving glycaemic control as is feasible with current treatment approaches. However, general application of such technology requires significant improvements in several areas, such as improvement of patency of catheter, pump failures due to early battery depletion incidents, and pump miniaturisation. Future perspective resides on insulin analogues with longer half-lives that would provide better basal insulin coverage in association with fast-acting analogues.
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Affiliation(s)
- G Emilien
- Laboratory of Pharmacology, Université Catholique de Louvain, Brussels, Belgium
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470
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Lee S, McAuliffe DJ, Flotte TJ, Kollias N, Doukas AG. Photomechanical transcutaneous delivery of macromolecules. J Invest Dermatol 1998; 111:925-9. [PMID: 9856797 DOI: 10.1046/j.1523-1747.1998.00415.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transcutaneous drug delivery has been the subject of intensive research. In certain situations, rapid transcutaneous delivery is very desirable. A mechanical (stress) pulse generated by a single laser pulse was shown to transiently increase the permeability of the stratum corneum in vivo. The barrier function of the stratum corneum recovers within minutes. The increased permeability during these few minutes allows macromolecules to diffuse through the stratum corneum into the viable epidermis and dermis. Macromolecules (40 kDa dextran and 20 nm latex particles) were deposited into the skin using a photomechanical pulse generated by a single 23 ns laser pulse. This treatment can potentially be utilized in therapies that currently require occlusive dressings for hours or day(s).
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Affiliation(s)
- S Lee
- Massachusetts General Hospital, Department of Dermatology, Harvard Medical School, Boston 02114, USA
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471
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Singer AJ, Shallat J, Valentine SM, Doyle L, Sayage V, Thode HC. Cutaneous tape stripping to accelerate the anesthetic effects of EMLA cream: a randomized, controlled trial. Acad Emerg Med 1998; 5:1051-6. [PMID: 9835465 DOI: 10.1111/j.1553-2712.1998.tb02661.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED Most medications are not absorbed topically due to the stratum corneum barrier. While effective as a topical anesthetic, EMLA cream is absorbed slowly, delaying its effects for up to one hour, thereby limiting its usefulness. OBJECTIVE To determine whether removal of the cornified layer of the skin by tape stripping (TS) would allow more rapid onset of anesthesia after topical application of EMLA cream prior to IV catheterization (IVC). METHODS This was a prospective, randomized, controlled trial comparing the levels of pain of IVC 15 minutes after topical application of EMLA cream in patients who had TS vs patients who did not. The setting was a suburban university-affiliated ED. A convenience sample of 68 alert adult patients requiring IVC were enrolled. The primary outcomes measured were pain of IVC and pain of TS using a previously validated 100-mm visual analog scale as well as the IVC success rate. RESULTS The pain of IVC was less for TS vs control patients [29.7 mm (95% CI=20.4 to 39.0 mm) vs 15.9 mm (95% CI=9.1 to 22.6 mm), p=0.017]. The mean pain of TS was 4.8+/-7.4 mm. The IVC success rate for TS vs control patients was 91% vs 74% (p=0.056). There were no adverse events after TS. CONCLUSIONS Removal of the cornified layer of the skin resulted in a more rapid anesthetic effect of EMLA cream as evidenced by lower IVC pain scores after TS. The effectiveness of TS for enhanced absorption of other medications should be investigated.
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Affiliation(s)
- A J Singer
- Department of Emergency Medicine, State University of New York at Stony Brook, USA.
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472
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Hikima T, Hirai Y, Tojo K. Effect of ultrasound application on skin metabolism of prednisolone 21-acetate. Pharm Res 1998; 15:1680-3. [PMID: 9833987 DOI: 10.1023/a:1011944209274] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The effect of ultrasound on skin penetration and metabolism of prednisolone (PN) and prednisolone 21-acetate (PNA) was investigated in the hairless mouse skin in vitro. METHODS The abdominal skin excised freshly was pretreated under different ultrasound intensities (4.32, 2.88, and 1.50 W/cm2) for 10, 30, and 60 min. The penetration/metabolism rate of PNA and its metabolite (PN) was then measured using a side-by-side diffusion cell. RESULTS The skin penetration of PN was enhanced by the ultrasound pretreatment. This enhancement was attributed to the decrease in the stratum corneum barrier capacity by ultrasound energy. The steady-state appearance rate of PN following the skin bioconversion of PNA decreased appreciably with increasing the product of the duration of pretreatment (Dp, min) and the intensity of ultrasound applied (Iu, W/cm2). When the product value was less than 40 W/cm2 . min, the steady-state appearance rate of the PN hardly increased in spite of the penetration enhancement of PNA. CONCLUSIONS These findings indicated a possible deactivation of the skin enzymes by ultrasound energy.
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Affiliation(s)
- T Hikima
- Department of Biochemical Science and Engineering, College of Computer Science and Biosystems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka, Japan
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473
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Pettit DK, Gombotz WR. The development of site-specific drug-delivery systems for protein and peptide biopharmaceuticals. Trends Biotechnol 1998; 16:343-9. [PMID: 9720323 DOI: 10.1016/s0167-7799(98)01186-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The desire to deliver protein and peptide biopharmaceuticals conveniently and effectively has led to intense investigation of site-specific drug-delivery systems. Despite challenges, progress towards the convenient noninvasive delivery of proteins and peptides has been achieved through specific routes of administration. In addition, the delivery of proteins and peptides to specific sites of action has been utilized to lower the total delivered dose, to gain access to specific organs or body compartments and to concentrate a therapeutic dose at a specific site of pharmacological action.
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Affiliation(s)
- D K Pettit
- Department of Analytical Chemistry and Formulation, Immunex, Seattle, WA 98101, USA.
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474
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Henry S, McAllister DV, Allen MG, Prausnitz MR. Microfabricated microneedles: a novel approach to transdermal drug delivery. J Pharm Sci 1998; 87:922-5. [PMID: 9687334 DOI: 10.1021/js980042+] [Citation(s) in RCA: 632] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although modern biotechnology has produced extremely sophisticated and potent drugs, many of these compounds cannot be effectively delivered using current drug delivery techniques (e.g., pills and injections). Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of skin. Because the primary barrier to transport is located in the upper 10-15 micron of skin and nerves are found only in deeper tissue, we used a reactive ion etching microfabrication technique to make arrays of microneedles long enough to cross the permeability barrier but not so long that they stimulate nerves, thereby potentially causing no pain. These microneedle arrays could be easily inserted into skin without breaking and were shown to increase permeability of human skin in vitro to a model drug, calcein, by up to 4 orders of magnitude. Limited tests on human subjects indicated that microneedles were reported as painless. This paper describes the first published study on the use of microfabricated microneedles to enhance drug delivery across skin.
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Affiliation(s)
- S Henry
- Institute for Bioengineering and Bioscience, School of Chemical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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475
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Wu J, Chappelow J, Yang J, Weimann L. Defects generated in human stratum corneum specimens by ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 1998; 24:705-710. [PMID: 9695274 DOI: 10.1016/s0301-5629(98)00049-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Over the last two decades, ultrasound (US) has been applied to enhance transdermal drug delivery. This method is called sonophoresis. The physical mechanism of the enhancement is far from being fully understood. It has been shown in our study that 168-kHz continuous US of spatially averaged pressure amplitude of 1.9 x 10(5) Pa induced a new structural state and generated defects (entrapped air pockets) in human stratum corneum specimens. The dimensions of the defects were found to be about 20 microns, large enough to allow the transdermal passage of high-molecular-weight drug molecules that normally elude the unenhanced transdermal drug delivery.
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Affiliation(s)
- J Wu
- Department of Physics, University of Vermont, Burlington 05405, USA
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476
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Liu J, Lewis TN, Prausnitz MR. Non-invasive assessment and control of ultrasound-mediated membrane permeabilization. Pharm Res 1998; 15:918-24. [PMID: 9647359 DOI: 10.1023/a:1011984817567] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE Ultrasound has been shown to transiently permeabilize biological membranes, thereby facilitating delivery of large compounds such as proteins and DNA into cells and across tissues such as skin. In this study, we sought to quantitatively determine the dependence of cell membrane permeabilization on ultrasound parameters and to identify acoustic signals which correlate with observed membrane permeabilization. METHODS Bovine red blood cells were exposed to ultrasound at 24 kHz over a range of controlled conditions. The degree of membrane permeabilization was measured by release of hemoglobin and was determined as a function of ultrasound parameters and measured acoustic signals. RESULTS These studies showed that permeabilization increased with incident ultrasound pressure, increased with total exposure time above a threshold of approximately 100 msec, showed a weak dependence on pulse length with a small maximum at 3 msec, and did not depend on duty cycle under the conditions examined. Using measured acoustic spectra we found that red blood cell membrane permeabilization correlated best with the pressure measured at half the driving frequency (f/ 2 = 12 kHz) and its ultraharmonics, less strongly with the broadband noise pressure measured between peaks, and least strongly with pressure measured at the driving frequency and its higher harmonics. Permeabilization caused by ultrasound applied at any set of conditions tested in this study could be well predicted by the parameter tau x Pf/2, which characterizes the total cavitational exposure. CONCLUSIONS This study provides a quantitative guide to designing ultrasound protocols useful for drug delivery. The acoustic measurements support the hypothesis that ultrasonic cavitation is the mechanism by which membranes are permeabilized. They also suggest that measurable acoustic signals can provide noninvasive, real-time feedback about membrane permeabilization and drug delivery.
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Affiliation(s)
- J Liu
- School of Chemical Engineering and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta 30332-0100, USA
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477
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Malghani MS, Yang J, Wu J. Generation and growth of bilayer defects induced by ultrasound. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 1998; 103:1682-1685. [PMID: 9514030 DOI: 10.1121/1.421263] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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478
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Frinking PJ, Bouakaz A, de Jong N, Ten Cate FJ, Keating S. Effect of ultrasound on the release of micro-encapsulated drugs. ULTRASONICS 1998; 36:709-712. [PMID: 9651601 DOI: 10.1016/s0041-624x(97)00122-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Although ultrasound is used extensively in medical therapies and diagnostics, it has been recognized only recently as a method for external controlled diversity of drugs. In this paper, firstly, a literature review on drug delivery and the combination with ultrasound is given. Then an experiment is described on measuring the release of a model drug (hexabrix) under ultrasound irradiation, from a polymer carrier.
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Affiliation(s)
- P J Frinking
- Thoraxcenter, Erasmus University, Rotterdam, The Netherlands.
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479
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Affiliation(s)
- Z Laron
- Endocrinology and Diabetes Research Unit, WHO Collaborative Center For Diabetes Education, Sackler Faculty of Medicine, Tel Aviv University, Israel
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480
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Singer AJ, Homan CS, Church AL, McClain SA. Low-frequency sonophoresis: pathologic and thermal effects in dogs. Acad Emerg Med 1998; 5:35-40. [PMID: 9444340 DOI: 10.1111/j.1553-2712.1998.tb02572.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Low-frequency sonophoresis has recently been shown to significantly facilitate transdermal permeability of various substances (e.g., insulin) in animal models, thus eliminating the need to inject such agents. Prior to human trials, the authors studied the safety profile of low-frequency sonophoresis in dogs by evaluating microscopic and temperature changes in the skin after sonophoresis. METHODS An evaluator-blinded canine study of sonophoresis using different energy intensities and probe diameters was performed. Low-frequency ultrasound was applied for 60 seconds to the clipped abdominal skin of 3 anesthetized adult mongrel dogs using a sonicator operating at a frequency of 20 KHz with a maximal energy output of 400 W. The sonicator was immersed in normal saline, and intensities of 4%, 10%, 20%, 30%, and 50% were applied during 600 msec of every second (pulsed mode). Three probes, 1-cm cylindrical, 5-cm cylindrical, and 10-cm disc-shaped, were evaluated. Each experimental condition was performed twice. Subcutaneous temperatures were measured by temperature probe before and after sonophoresis. At 30 minutes post-sonophoresis, full-thickness skin biopsies were taken for blinded histopathologic evaluation. RESULTS Minimal urticarial reactions were noted with the 1-cm probe at intensities of < or = 20% and with the 5-cm probe at 4% intensity. With higher intensity, thermal injuries were observed grossly with erythema and vesicles. The microscopic correlates were papillary and dermal edema with neutrophils and telangiectasia. The conditions producing vesicles grossly had foci of epidermal necrosis, subepidermal vesicles, and degeneration of papillary dermal collagen. With still higher intensities, confluent epidermal necrosis became apparent. Use of the 10-cm probe did not result in any injury. CONCLUSIONS Low-frequency ultrasound at low intensities appears safe for use to enhance the topical delivery of medications, producing only minimal urticarial reactions. Higher-intensity conditions resulted in second-degree burns, most likely attributable to localized heating.
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Affiliation(s)
- A J Singer
- Department of Emergency Medicine, State University of New York, University Medical Center, Stony Brook, NY, USA.
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481
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Benson HAE, Prankerd RJ. Optimisation of Drug Delivery: 4. Transdermal Drug Delivery. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/jppr1997276441] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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482
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Lejbkowicz F, Salzberg S. Distinct sensitivity of normal and malignant cells to ultrasound in vitro. ENVIRONMENTAL HEALTH PERSPECTIVES 1997; 105 Suppl 6:1575-8. [PMID: 9467085 PMCID: PMC1469937 DOI: 10.1289/ehp.97105s61575] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The effect of ultrasonic irradiation on the viability of human normal (foreskin fibroblast and amniotic fluid epithelial) and tumor (breast carcinoma, melanoma, and lung carcinoma) cells lines was studied. Cells were subjected to ultrasonic irradiation with a frequency of 20 kHz and an intensity of 0.33 W/cm2 for variable periods of time. Several parameters were tested to determine the effects of ultrasonic irradiation on cell viability and cellular function. Normal cells were relatively resistant to ultrasonic irradiation, whereas malignant cells were much more sensitive. Maximum damage occurred 4 min after exposure of the malignant cells to irradiation. Cellular DNA and protein synthesis were significantly affected as a function of time of irradiation and cloning efficiency of malignant cells exposed to irradiation was greatly reduced. To generalize the consistency of the ultrasonic effect, studies on additional normal and malignant human cells of distinct origin are under way to test their sensitivity to ultrasonic irradiation. Thus, the applicability of ultrasonic irradiation as an antitumor agent may be important in the development of a new methodology in the treatment of cancer.
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Affiliation(s)
- F Lejbkowicz
- Institute of Clinical Immunology, Rambam Medical Center, Haifa, Israel.
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483
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Mitragotri S, Blankschtein D, Langer R. An explanation for the variation of the sonophoretic transdermal transport enhancement from drug to drug. J Pharm Sci 1997; 86:1190-2. [PMID: 9344179 DOI: 10.1021/js960528v] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Over the last few decades, application of therapeutic ultrasound (frequency between 1 and 3 MHz and intensity between 1 and 2 W/cm2) has been attempted to enhance transdermal transport of several drugs, a method referred to as sonophoresis. The sonophoretic enhancement of transdermal drug transport was found to vary significantly from drug to drug. In certain cases, ultrasound did not induce any enhancement of transdermal drug transport. This variation in the efficacy of sonophoresis has raised a controversy regarding its applicability as a transdermal delivery enhancer. The objective of this paper is to provide a summary of the literature data on sonophoresis and an explanation for the observed variation of the sonophoretic enhancement from drug to drug. This paper also presents an equation to qualitatively predict whether therapeutic ultrasound may enhance transdermal transport of a given drug based on knowledge of the drug passive skin permeability and octanol-water partition coefficient.
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Affiliation(s)
- S Mitragotri
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA
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484
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Johannesen J, Petersen KF, Berger M, Binder C. New insulins and other possible therapeutic approaches. Diabetologia 1997; 40 Suppl 3:B89-93. [PMID: 9345654 DOI: 10.1007/bf03168195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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485
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Rapoport N, Smirnov AI, Timoshin A, Pratt AM, Pitt WG. Factors affecting the permeability of Pseudomonas aeruginosa cell walls toward lipophilic compounds: effects of ultrasound and cell age. Arch Biochem Biophys 1997; 344:114-24. [PMID: 9244388 DOI: 10.1006/abbi.1997.0176] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The objective of this research was to elucidate the factors effecting the permeability of cell membranes of gram-negative bacteria toward hydrophobic compounds. Ultrasound treatment, cell age, and the phase state of phospholipid membranes were considered. Spin-labeling EPR method was used to quantify the penetration and distribution of a lipophilic spin probe, 16-doxylstearic acid (16-DS), in Pseudomonas aeruginosa cell membranes. This bacterium was chosen because of its reported resistance to the action of hydrophobic antibiotics caused by the low permeability of the outer cell membrane for hydrophobic compounds. EPR spectra were collected from cell pellets and cell lysates. The overall spin probe uptake was measured in 10% SDS-cell lysates. Lysis with 0.6% SDS revealed the fraction of the probe located in membrane sites readily accessible to the surfactant. The results indicated a structural heterogeneity of P. aeruginosa membranes, with the presence of structurally "stronger" and "weaker" sites characterized by different susceptibility to the SDS treatment. The intracellular concentration of 16-DS was higher in insonated cells and increased linearly with the sonication power. EPR spectra indicated that ultrasound enhanced the penetration of the probe into the structurally stronger sites of the inner and outer cell membranes. The effect of ultrasound on the cell membranes was transient in that the initial membrane permeability was restored upon termination of the ultrasound treatment. These results suggest that the resistance of gram-negative bacteria to the action of hydrophobic antibiotics was caused by a low permeability of the outer cell membranes. This resistance may be reduced by the simultaneous application of antibiotic and ultrasound. This hypothesis was confirmed in our experiments with P. aeruginosa exposed to erythromycin.
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Affiliation(s)
- N Rapoport
- Department of Materials Science and Engineering, University of Utah, Salt Lake City 84112, USA.
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486
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Wyber JA, Andrews J, D'Emanuele A. The use of sonication for the efficient delivery of plasmid DNA into cells. Pharm Res 1997; 14:750-6. [PMID: 9210192 DOI: 10.1023/a:1012198321879] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE Ultrasonic methods have considerable potential for the introduction of macromolecules into cells. In this paper we demonstrate that, under controlled conditions, application of 20 kHz ultrasound to a suspension of yeast cells facilitates the delivery of plasmid DNA into these cells. METHODS Aliquots of growing yeast cells (Saccharomyces cerevisae, strain AH22) were suspended in buffer and exposed to 20 kHz ultrasound from a laboratory (probe-type) sonicator in the presence of microgram quantities of plasmid DNA. Efficiency of DNA delivery was scored as the number of cells transformed. RESULTS Cell transformation was optimal at 30 seconds sonication using an output of 2.0 watts and resulted in a 20 fold enhancement over control values. At extended sonication times, fewer cells showed evidence of transformation because of reduced cell viability. The increased DNA uptake and the decreased cell viability were both attributable to acoustic cavitation events during sonication. The extent of acoustic cavitation was measured and it was found that there was an increase in cavitation events with increased sonication time. Cell viability was shown to be directly related to the number of cavitation events. The effects of sonication on plasmid DNA were investigated and indicated that the structural integrity of plasmid DNA was unaffected by the sonication conditions employed. CONCLUSIONS Under controlled conditions, ultrasound is an effective means of delivering plasmid DNA into cells. The subsequent expression of DNA molecules in cells depends upon a balance between transient cell damage and cell death.
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Affiliation(s)
- J A Wyber
- School of Pharmacy and Pharmaceutical Sciences, University of Manchester, UK
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487
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Weaver JC, Vanbever R, Vaughan TE, Prausnitz MR. Heparin alters transdermal transport associated with electroporation. Biochem Biophys Res Commun 1997; 234:637-40. [PMID: 9175766 DOI: 10.1006/bbrc.1997.6701] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Short, high-voltage (HV; U(skin,max) approximately 100 V) pulses have been shown to increase rates of transdermal transport by several orders of magnitude via a mechanism hypothesized to involve electroporation. We show that heparin, a linear, highly charged macromolecule, significantly alters the molecular transport capacity and lifetime of aqueous pathways across human stratum corneum (SC) created by such pulses. If co-transported during pulsing, heparin molecules can interact with the SC and other molecules, thereby altering ionic and molecular transport. We also observed an increase in post-pulse skin permeability and persistent lower skin resistance. Because most heparin molecules are long enough to span the five to six lipid bilayer membranes that separate corneocytes within the SC, these results can be explained by the hypothesis that heparin molecules were trapped within the skin, holding open pathway segments connecting adjacent corneocytes. These results support the skin electroporation hypothesis and provide the first demonstration of a chemical enhancer effect for transdermal transport by HV pulsing.
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Affiliation(s)
- J C Weaver
- Harvard-M.I.T. Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
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488
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Lu B, Federoff HJ, Wang Y, Goldsmith LA, Scott G. Topical application of viral vectors for epidermal gene transfer. J Invest Dermatol 1997; 108:803-8. [PMID: 9129236 DOI: 10.1111/1523-1747.ep12292254] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Efficient gene transfer with extended gene expression is essential for successful treatment of skin diseases using gene therapy. Previously we evaluated a physical gene transfer method (gene gun delivery) for its ability to transfect the epidermis in vivo. In this study, we tested two viral vectors for their ability to transduce murine epidermis through topical application. Both an adenoviral vector and a herpes simplex virus (HSV) amplicon vector transduced murine epidermis with high efficiency after topical application. Differences in amount and duration of transgene expression were compared between these two vectors. Quantitative analysis of reporter lacZ gene expression showed that the viral vector-mediated gene transfers were superior to gene-gun delivery of plasmid DNA. Significant necrosis and cytotoxicity, however, were observed in the HSV-treated skin. In addition, we show that murine epidermis developed hyperkeratosis and acanthosis 4 d after an adenoviral vector containing a human TGF-alpha expression unit was applied topically. Finally we demonstrate the feasibility of transduction of fetal skin in utero by intraamniotic injection of an adenovirus vector.
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Affiliation(s)
- B Lu
- Department of Dermatology, University of Rochester School of Medicine and Dentistry, New York 14642, USA
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489
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Yamashita N, Tachibana K, Ogawa K, Tsujita N, Tomita A. Scanning electron microscopic evaluation of the skin surface after ultrasound exposure. Anat Rec (Hoboken) 1997; 247:455-61. [PMID: 9096784 DOI: 10.1002/(sici)1097-0185(199704)247:4<455::aid-ar3>3.0.co;2-q] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Transdermal drug-delivery systems have become widely accepted clinically for the administration of several systemic drugs. Recently, research on ultrasound irradiation to facilitate the penetration of drugs through the skin have been reported. The present study investigated the morphological changes induced in skin after ultrasound irradiation to hairless mouse skin and human skin. METHODS Hairless mice and human skin were immersed in an ultrasound irradiation water tank. Ultrasound was delivered for a duration of 5 min. Ultrasound frequency of 48 kHz was generated at an intensity of 0.5 W/cm2. The surface of the skin was observed with scanning electron microscopy for comparison with skin samples unexposed to ultrasound energy. RESULTS For hairless mouse exposed to ultrasound, the cells of the stratum corneum of the skin surface were almost completely removed. The polygonal cells of the stratum spinosum and basal cells were exposed. In addition, large craterlike pores with a diameter of 100 microns were formed sporadically in some of the skin samples. In contrast, the surface of human skin exposed to ultrasound showed only slight removal of keratinocytes around the hair follicles. CONCLUSION The removal of the stratum corneum and other alterations in hairless mouse and human skin by ultrasound may explain the enhancement of transdermal drug penetration. The effect on human skin was relatively minor compared with that on hairless mouse skin.
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Affiliation(s)
- N Yamashita
- First Department of Anatomy, Fukuoka University School of Medicine, Nanakuma, Japan
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490
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Abstract
Ultrasound permeabilizes Chinese hamster ovary (CHO) cells for the endonucleases AluI and benzon nuclease which leads to the induction of chromosomal aberrations by these enzymes. A few aberrant cells were observed when trypsinized cells or adherent cells were exposed to the enzymes in the absence of ultrasound. Our data show that sonication can be used to introduce endonucleases into CHO cells. We further demonstrate that few cells can internalize endonucleases without previous permeabilization.
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Affiliation(s)
- C Johannes
- University of Essen, Department of Genetics, Germany
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491
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Affiliation(s)
- J Brange
- Novo Nordisk A/S, Bagsvaerd, Denmark
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492
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Abstract
Transdermal administration by iontophoresis (enhanced transport via the skin using the driving force of an applied electric field) has been successfully demonstrated but no formal relationship between peptide sequence/structure and efficiency of delivery has been established. There are notable examples, such as the lipophilic leutinizing hormone releasing hormone (LHRH) analogs, Nafarelin and Leuprolide, that exhibit down-regulation of their own transport across the skin under the influence of an iontophoretic current. The hypothesis that this phenomenon is due to neutralization of the skin's net negative charge by these cationic peptides was examined with LHRH oligopeptides. The impact of these compounds on the electroosmotic flow of solvent into the skin, which is induced by iontophoresis and which contributes significantly to the electrotransport of large, positively charged ions, was examined and quantified. Close juxtaposition of cationic and lipophilic residues profoundly inhibited electroosmosis and, presumably, peptide flux. The results indicate that the lipophilicity of the oligopeptides facilitates van der Waals interactions with hydrophobic patches along the transport route, thereby permitting the positively charged oligopeptide to interact with carboxylate side chains that give the skin its net negative charge at neutral pH. The lipophilic, cationic oligopeptide, therefore, becomes anchored in the transport path, neutralizing the original charge of the membrane, and completely altering the permselective properties of the skin.
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Affiliation(s)
- J Hirvonen
- Department of Biopharmaceutical Sciences, University of California-San Francisco, CA 94143-0446, USA
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493
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Affiliation(s)
- R H Guy
- Centre Interuniversitaire de Recherche et d'Enseignement, Pharmapeptides, Campus Universitaire, Archamps, France
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494
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Zhang I, Shung KK, Edwards DA. Hydrogels with enhanced mass transfer for transdermal drug delivery. J Pharm Sci 1996; 85:1312-6. [PMID: 8961145 DOI: 10.1021/js9601142] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The sonophoretic transport rates of monomeric insulin and vasopressin across human skin in vitro in the presence of a 20 kHz ultrasound field are shown to differ substantially depending on whether molecules enter the skin from a saline solution or from a viscous ultrasonic coupling medium (specifically, a methyl cellulose hydrogel or viscous sol). Theoretically, the reduction in sonophoretic transport caused by the hydrogels can be explained by boundary layers that form within the hydrogel owing to the relatively rapid rate of molecular transport across the (ultrasonically) permeated stratum corneum as well as poor diffusive mass transfer between the skin and gel. The results of in vitro experiments performed with an ac current accompanying the ultrasound show that the mass-transfer barrier posed by the hydrogel can be eliminated for both vasopressin and insulin by suppressing the diffusive boundary layers, indicating that relatively high rates of sonophoretic molecular transport across human skin are achievable when hydrogels are used as the ultrasound coupling medium as long as method is used to induce molecular mixing within the gel.
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Affiliation(s)
- I Zhang
- Department of Chemical Engineering, 204 Fenske Lab, PA 16802, USA
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495
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Danilenko DM, Ring BD, Pierce GF. Growth factors and cytokines in hair follicle development and cycling: recent insights from animal models and the potentials for clinical therapy. MOLECULAR MEDICINE TODAY 1996; 2:460-7. [PMID: 8947911 DOI: 10.1016/1357-4310(96)10045-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hair growth disorders, particularly those that lead to hair loss (alopecia), are common and frequently cause significant mental anguish in affected individuals. The mechanisms underlying the majority of these disorders are unknown. However, insights into the specific molecular mechanisms of hair follicle development and cycling have recently been made using animal models, particularly mice that over- or underexpress a specific gene for a growth factor or cytokine. Other animal models have demonstrated that certain growth factors and cytokines can prevent much of the alopecia caused by cancer chemotherapeutic agents. These animal models have confirmed the importance of growth factors and cytokines in hair follicle development and cycling, and have formed the foundation for potential clinical therapy of hair growth disorders, particularly alopecia. Nevertheless, important questions concerning their efficacy, safety and delivery will need to be answered before successful clinical therapy of any hair growth disorder becomes a reality.
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Affiliation(s)
- D M Danilenko
- Department of Pathology, Amgen Inc., Thousand Oaks, CA 91320-1789, USA.
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496
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497
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Johnson ME, Mitragotri S, Patel A, Blankschtein D, Langer R. Synergistic effects of chemical enhancers and therapeutic ultrasound on transdermal drug delivery. J Pharm Sci 1996; 85:670-9. [PMID: 8818988 DOI: 10.1021/js960079z] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effects of (i) a series of chemical enhancers and (ii) the combination of these enhancers and therapeutic ultrasound (1 MHz, 1.4 W/cm2, continuous) on transdermal drug transport are investigated. A series of chemical enhancer formulations, including (i) polyethylene glycol 200 dilaurate (PEG), (ii) isopropyl myristate (IM), (iii) glycerol trioleate (GT), (iv) ethanol/pH 7.4 phosphate buffered saline in a 1:1 ratio (50% EtOH), (v) 50% EtOH saturated with linoleic acid (LA/EtOH), and (vi) phosphate buffered saline (PBS), as a control, are evaluated using corticosterone as a model drug. LA/EtOH is the most effective of these enhancers, increasing the corticosterone flux by 900-fold compared to that from PBS. Therapeutic ultrasound (1 MHz, 1.4 W/cm2, continuous) increases the corticosterone permeability from all of the enhancers examined by up to 14-fold (LA/EtOH) and increases the corticosterone flux from the saturated solutions by up to 13,000-fold (LA/EtOH), relative to that from PBS. Similar enhancements are obtained with LA/EtOH with and without ultrasound for four other model drugs, dexamethasone, estradiol, lidocaine, and testosterone. The permeability enhancements for all of these drugs resulting from the addition of linoleic acid to 50% EtOH increase with increasing drug molecular weight. Likewise, the permeability enhancement attained by ultrasound and LA/EtOH relative to passive EtOH exhibits a similar size dependence. A mechanistic explanation of this size dependence is provided. It is suggested that bilayer disordering agents, such as linoleic acid and ultrasound, transform the SC lipid bilayers into a fluid lipid bilayer phase or create a separate bulk oil phase. The difference in diffusivity of a given solute in SC bilayers and in either fluid bilayers or bulk oil is larger for larger solutes, thereby producing greater enhancements for larger solutes.
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Affiliation(s)
- M E Johnson
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA
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498
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Machet L, Pinton J, Patat F, Arbeille B, Pourcelot L, Vaillant L. In vitro phonophoresis of digoxin across hairless mice and human skin: Thermal effect of ultrasound. Int J Pharm 1996. [DOI: 10.1016/0378-5173(96)04447-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Colombo P, Bettini R, Peracchia MT, Santi P. Controlled release dosage forms: from ground to space. Eur J Drug Metab Pharmacokinet 1996; 21:87-91. [PMID: 8839681 DOI: 10.1007/bf03190256] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Controlled release of drugs is one of the most significant advances in pharmacy. Due to the proposition of new routes for drug administration, today it is considered as a part of 'drug delivery'. Developments in biotechnology producing natural molecules, peptides and proteins have allowed high activity substances that require careful formulation for administration. Drug delivery is the discipline striving to sole the problem of optimisation of drug efficacy. In this contribution the last 25 years of drug delivery research have been examined pointing out the most significant break-through steps.
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Affiliation(s)
- P Colombo
- Dipartimento Farmaceutico, Università di Parma, Italy
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Abstract
Over the past decade there has been considerable interest shown in an understanding of the mechanisms of skin penetration and its enhancement. Sophisticated biophysical techniques have been used to probe, at a molecular level, the ways in which chemical and physical enhancement can be achieved. Two types of chemical penetration enhancers can be identified and their co-administration can result in synergistic effects. Another attractive method for enhancing skin penetration is the use of supersaturation but problems associated with stability must be addressed. Biotech drugs are inherently difficult to administer and recent progress using iontophoresis and sonophoresis has identified that medicines of this type can be delivered percutaneously. It is also possible to use the percutaneous route to monitor plasma levels non-invasively. Coupling non invasive monitoring with controlled delivery allows the possibility of creating transdermal systems which act with bio feedback.
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Affiliation(s)
- J Hadgraft
- Welsh School of Pharmacy, University of Wales, Cardiff, UK
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