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At least 649 records · Page 36Linked to original sources
PubMed2005

Effects of vehicle and region of application on absorption of hydrocortisone through canine skin.

OBJECTIVE: To determine the effects of various vehicles on the penetration and retention of hydrocortisone applied to canine skin. SAMPLE POPULATION: 20 canine skin samples obtained from the thorax, neck, and groin regions of 5 Greyhounds. PROCEDURE: Skin was harvested from dogs after euthanasia and stored at -20 degrees C until required. The skin was then defrosted and placed into diffusion cells, which were maintained at approximately 32 degrees C by a water bath. Saturated solutions of hydrocortisone that contained trace amounts of radiolabelled [14C]-hydrocortisone in each vehicle (ie, PBS solution [PBSS] alone, 50% ethanol [EtOH] in PBSS [wt/wt], and 50% propylene glycol in PBSS [wt/wt]) were applied to the outer (stratum corneum) surface of each skin sample, and aliquots of receptor fluid were collected for 24 hours and analyzed for hydrocortisone. RESULTS: The maximum flux of hydrocortisone was significantly higher for all sites when dissolved in a vehicle containing 50% EtOH, compared with PBSS alone or 50% propylene glycol, with differences more prominent in skin from the neck region. In contrast, higher residues of hydrocortisone were found remaining within the skin when PBSS alone was used as a vehicle, particularly in skin from the thorax and neck. CONCLUSIONS AND CLINICAL RELEVANCE: Penetration of topically applied hydrocortisone is enhanced when EtOH is used in vehicle formulation. Significant regional differences (ie, among the thorax, neck, and groin areas) are also found in the transdermal penetration and skin retention of hydrocortisone. Variability in clinical response to hydrocortisone can be expected in relation to formulation design and site of application.

Administration, Cutaneous↗
PubMed1986

Quantification of texture match of the skin graft: function and morphology of the stratum corneum.

In an attempt to analyze the "texture match" of grafted skin, functional and morphological aspects of the stratum corneum were studied using the Skin Surface Hydrometer (IBS Inc.) and the scanning electron microscope. The results showed that hygroscopicity and water holding capacity of the stratum corneum played a crucial role in making the skin surface soft and smooth. Morphologically there were regional differences in the surface pattern and the mean area of corneocytes, suggesting that these differences affect skin texture. It is suggested that the present functional and morphological studies of the stratum corneum can provide a quantitative measure of the "texture match".

Adolescent↗
PubMed1979

Penetration of cephradine and cefazolin into ulcers of patients suffering from peripheral arterial circulatory insufficiency.

11 patients with peripheral arterial circulatory insufficiency with ulcers on the big toe or on the heel were given 1 g of cephradine intravenously (i.v.) and later 1 g of cefazolin i.v., two cephalosporins with different degrees of protein binding. Antibiotic concentrations were followed in serum and wound secretions after the injections. The peripheral circulatory state of the patients and the degree of protein binding of the cephalosporins used seemed to be of minor importance for the concentrations of the antibiotics in the ulcers, i.e. the infectious focus, compared to local factors such as the bacterial flora of the ulcers. In-vitro studies with bacterial strains isolated from the ulcers of 2 of the patients indicated that beta-lactamases from gram-negative bacteria might be at least part of the explanation for the low concentrations in wound secretion of one or other of the agents used in 4 out of the 11 patients.

Aged↗
PubMedDate not supplied

Flow conductivity of rat dermis is determined by hydration.

The flow rate of phosphate buffered saline through dermis was measured as a function of applied pressure. Hyaluronan and collagen, the two principal materials which confirm resistance to flow in dermis, were not lost from the tissue during the experiments which lasted up to two days. From Darcy's Law, the average flow conductivities were 2 to 6 x 10(-12) cm4/dyn x s and decreased with increasing applied pressure. We conclude that the tissue is compacted in proportion to the applied pressure during the flow experiments. The hydraulic flow conductivity is described mathematically as a function of compaction induced by the applied pressure.

Animals↗
PubMedDate not supplied

Iontophoresis in dermatology.

Iontophoresis is the process of increasing the penetration of drugs into the skin by application of an electric current. The drug is applied under an electrode of the same charge as the drug, and a return electrode opposite in charge to the drug is placed at a neutral site on the body surface. Electrical energy assists the movement of ions across the skin using the principle "like charges repel each other and opposite charges attract". In this article, we discuss the mechanism, principles, factors influencing iontophoresis and its application for various dermatological conditions.

Administration, Topical↗
PubMedDate not supplied

Permeation enhancers compatible with transdermal drug delivery systems. Part I: selection and formulation considerations.

Part I of this article reviews the classification, chemistry, properties, selection, and use of skin permeation enhancers in transdermal drug delivery systems and dermal patches. The authors discuss ideal properties of enhancers and describe various enhancers' actions on the skin. Part II will describe interactions between permeation enhancers and other transdermal delivery system components, such as backing materials, pressure-sensitive adhesives, membranes, and release liners. Adhesive properties critical to the optimization of a transdermal formulation will be discussed.

Adjuvants, Pharmaceutic↗
PubMedDate not supplied

Permeation enhancers compatible with transdermal drug delivery systems: part II: system design considerations.

Part I of this article reviewed the classification, chemistry, properties, selection, and use of skin permeation enhancers in transdermal drug delivery systems and dermal patches. In Part II, the authors discuss ideal properties of enhancers and describe various enhancers' actions on the skin, as well as interaction among permeation enhancers and other transdermal delivery system components, such as backing materials, pressure-sensitive adhesives, membranes, and release liners. Adhesive properties critical to the optimization of a transdermal formulation are discussed.

Adjuvants, Pharmaceutic↗
PubMedDate not supplied

Epicutaneous and transcutaneous immunization using DNA or proteins.

Mucocutaneous surfaces are constantly exposed to an array of exogenous antigens including environmental proteins, peptides and low molecular weight and microbial pathogens. These tissues are covered by an epithelium which exerts both the role of a barrier, limiting the penetration of microbes and of hydrophylic antigenic moieties, but at the same time ensures that antigens which penetrate through the epithelium are rapidly captured and transported to draining lymph nodes for initiation of a specific immune response. Epithelial dendritic cells represent the immunocompetent cells responsible for the dynamic uptake and presentation of antigen entering peripheral tissues, and are unique in their efficiency in triggering the immune system and in initiating a primary immune response.

Administration, Cutaneous↗
PubMed1976

[Skin mediator reactivity in workers in contact with lead].

The intracutaneous adrenomimetic test is discussed against the background of overall neurovascular reactivity. The skin-mediator test is recommended as a reference of the functional condition of vegetovasal substrates. A certain degree of synchronization between dermal reaction and degree of clinical syndromes and their stages is sought for. Emphasis is laid on parasympathetic excitation in the initial stage. Adrenergic reactivity considered in a constellation with the other indicators, has a definite diagnostic-prognostic value.

Adult↗
PubMed1976

Effects of ethanol on the permeability of frog skin.

Ethanol (3%) decreases the potential difference and short-circuit current across the isolated frog skin in chloride Ringer's solution. Unidirectional fluxes of Na and Cl indicate that the drop in short-circuit current is due to an inhibition of the sodium influx. However, ethanol had no effect on the electrical parameters or sodium fluxes, when the frog skin was bathed in chloride-free solutions on both sides or the outside alone. The ethanol response is anion-dependent. In addition, chloride-free media in the inside bathing solution reduced the short-circuit current, indicating a sodium transport pathway which is dependent on chloride and confirming previous data in the literature. Other anions such as sulfate and nitrate could not substitute for chloride. The vasopressin-induced natriferic response and the ethanol effect were found to work independently of each other and different pathways of action are suggested for these agents. The intracellular sodium content of the isolated frog skin epithelium increased and potassium decreased in the presence of the Na-K adenosine triphosphatase inhibitor, ouabain, whereas ethanol or amiloride had no effect. The oxygen consumption of the isolated frog skin was unaffected by up to 10% ethanol. A general metabolic action is probably thus not mediating the response. Urea, in iso-osmotic concentrations to the ethanol, did not mimic its effect. Tritiated water fluxes (in the absence of an osmotic gradient) were reduced by 30% in the presence of 3% ethanol. It is suggested that ethanol may impede the flow of water across frog skin by a physicochemical interaction with membrane pores and the water molecules. The permeability coefficient (Ktrans) for ethanol was found to be 10 times smaller than the Ktrans for water.

Animals↗