0000000000247587
AUTHOR
Richard H. Guy
showing 5 related works from this author
Iontophoresis: electrorepulsion and electroosmosis.
2000
Over the last 10-15 years, the electrical enhancement of drug delivery across the skin has undergone intense investigation. During this period, considerable amounts of experimental data have been generated, and the successful enhancement of a diverse array of molecules has been achieved. Indeed, the commercial exploitation of the method can be envisaged within the next few years. Despite this progress, however, the mechanistic understanding of iontophoresis remains a challenging scientific question that is yet to be fully resolved. The routes of permeation under the influence of an applied electrical potential, and the molecular interactions of the transporting drug with these pathways, hav…
Transdermal therapy and diagnosis by iontophoresis
1997
Iontophoresis, the use of an electric current to drive charged molecules across the skin, has the potential to expand the feasible range of drugs for transdermal administration significantly. This method of delivery is being examined carefully with respect to higher-molecular-weight therapeutics (in particular, peptides and small proteins), which cannot be absorbed following oral administration and for which, at this time, an invasive injection remains the only option. In addition, the procedure of so-called 'reverse' iontophoresis would appear to represent a truly noninvasive approach for diagnostic monitoring of blood chemistry.
Transdermal and Skin-Targeted Drug Delivery
1997
Background: The application of therapeutic agents to the skin addresses three general objectives: (a) the treatment of a variety of dermatologic diseases; (b) the “targeted” delivery of drugs to deeper subcutaneous tissues, with a concomitant reduction in systemic exposure; and (c) socalled transdermal administration to elicit a systemic pharmacologic effect. Objective: Recently, significant progress towards all three goals has been recorded and the level of research and development activity remains high. We aim to discuss these advances from mechanistic and clinical standpoints. Results: For the topical treatment of skin disease, novel vehicles (e.g., stabilized, supersaturated systems and…
Application of the threshold of toxicological concern (TTC) to the safety evaluation of cosmetic ingredients.
2007
The threshold of toxicological concern (TTC) has been used for the safety assessment of packaging migrants and flavouring agents that occur in food. The approach compares the estimated oral intake with a TTC value derived from chronic oral toxicity data for structurally-related compounds. Application of the TTC approach to cosmetic ingredients and impurities requires consideration of whether route-dependent differences in first-pass metabolism could affect the applicability of TTC values derived from oral data to the topical route. The physicochemical characteristics of the chemical and the pattern of cosmetic use would affect the long-term average internal dose that is compared with the re…
Noninvasive sampling of phenylalanine by reverse iontophoresis.
1999
While iontophoresis is typically associated with drug delivery across the skin, the symmetry of the technique permits its application to the essentially noninvasive withdrawal of biologically important analytes from the subcutaneous space to the body's surface. The identification of other substances which can be monitored by this procedure, and to its optimization and development as a more general clinical chemistry tool, is a long-term objective. In this paper, we describe a preliminary in vitro investigation into the feasibility of extracting and analyzing the amino acid, phenylalanine, with the ultimate aim to develop a diagnostic test for phenylketonuria, a potentially fatal metabolic d…