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At least 631 records · Page 35Linked to original sources
PubMed1997

Evaluation of Yucatan micropig skin for use as an in vitro model for skin permeation study.

Skin permeation rates of five non-steroidal anti-inflammatory drugs, three of them lipophilic (ibuprofen, indomethacin and ketoprofen) and two hydrophilic (sodium diclofenac and antipyrine), through Yucatan hairless micropig (YMP) full-thickness skin were determined in vitro using Franz-type diffusion cells, and the usefulness of YMP skin as an animal model skin was investigated. Five-month-old YMP skin showed small variation with respect to drug permeation rates, if the region of skin site was the same. But skin from 6-month-old YMPs showed faster and varied permeation rates due to skin defects. In the case of hydrophilic drugs, no effects on permeation due to the region from which the skin was obtained were observed, although higher permeation rates were observed through the flank than through dorsal skin in the case of ibuprofen and ketoprofen. For YMP skin, the permeation coefficients of drugs were lower than those for hairless rat skin, especially for hydrophilic drugs. Compared with reported human data on permeation coefficients, the permeation coefficients of drugs through YMP skin were 1/2-1/8 of those through human skin, regardless of whether the drugs were hydrophilic or lipophilic. YMP skin could be used as an in vitro animal skin model because of the reproducibility of the permeation rate of drugs through this skin and its similarity to human skin.

Administration, Topical↗
PubMed2001

Transdermal drug delivery by electroporation applied on the stratum corneum of rat using stamp-type electrode and frog-type electrode in vitro.

Transdermal enhancement effects of electroporation applied only on the stratum corneum by two electrode types, the stamp-type electrode and the frog-type electrode, were investigated in vitro using excised rat skin. Carboxyfluorescein (CF) was selected as a model compound. The excised skin was set in a Franz type diffusion cell and a square wave electric pulse was applied to the stratum corneum under various electric pulse conditions. We determined the permeability of CF to the receptor compartment under these conditions. Voltage, electric pulse length, and number of electric pulses, were varied from 10 to 1000 V, 50 micros to 15 ms and 5 to 30 pulses, respectively. Flux rate was enhanced as the electric pulse condition strengthened. However, the maximum value was attained in the flux rate, above which no increase was observed despite strengthening of the electric pulse. Although at low electric pulses, the enhancement effect of the frog-type electrode was superior to that of the stamp-type electrode, the maximum flux rates were the same. These results indicate that electroporation on the stratum corneum using the stamp-type electrode or frog-type electrode, is useful for transdermal drug delivery.

Administration, Cutaneous↗
PubMed2004

Skin whitening effect of linoleic acid is enhanced by liposomal formulations.

Linoleic acid (LA) is known to have a whitening effect on hyperpigmented skin, and is encapsulated in liposomes for topical application because of its low solubility in aqueous solution, although the effect of liposomalization of LA on the whitening activity has not been evaluated. In the present study, we evaluated the effect of liposomalization on the whitening activity of LA by using LA in ethanol, hydrogel containing LA, and hydrogel containing liposomal LA towards the UV-stimulated hyperpigmented dorsal skin of brownish guinea pigs. The whitening effect was far greater for hydrogel containing liposomal LA (0.1% w/w as a final concentration of LA) than for free LA in ethanol or hydrogel containing LA. Next, the whitening effect of LA was examined with UV-stimulated hyperpigmented human upper arm skin by using a hydrogel containing liposomal LA (0.1% LA) and non-liposomal LA (3.0, 10.0% LA). Liposomal LA (0.1%) showed a whitening effect comparable to 10.0% non-liposomal LA and was far more effective than 3.0% non-liposomal LA. These results indicate that liposomal formulations are favorable for the transdermal application of LA.

Administration, Cutaneous↗
PubMed1999

Effects of removal of stratum corneum, delipidization and addition of enhancers, ethanol and l-menthol, on skin permeation of benzoic acid and its 4-n-alkyl substituents in excised guinea pig dorsal skin.

Skin penetration of benzoic acid and its 4-alkyl substituents (methyl, ethyl, n-propyl and n-butyl) through excised guinea pig dorsal skin was examined, and effects of removal of stratum corneum, delipidization and addition of the penetration enhancers, ethanol and l-menthol plus ethanol, were observed. Permeability coefficients, which increased with the increase in their alkyl chain lengths, depended on the ratio of undissociated form of the derivatives. Removal of stratum corneum by tape stripping and delipidization by a chloroform-methanol mixture, whose effects on the permeation were similar, increased the permeability coefficients of the derivatives, especially those of relatively hydrophilic derivatives. Addition of 1% l-menthol plus 15% ethanol increased the permeability coefficient of benzoic acid, but decreased those of ethyl-, n-propyl- and n-butyl-substituents, and differences in the permeability coefficients among these acids almost disappeared. A similar though weaker tendency was observed for the effects of 15% ethanol itself. Analysis of transfer free energy of the methylene group from vehicle to skin revealed that tape stripping and delipidization induced the reduction of lipophilic barrier property, although it still remained after these treatments. The analysis also showed that the addition of the enhancers made the skin relatively more hydrophilic compared to the vehicle, which induced an increase in permeability coefficient of benzoic acid and decreases in those of its lipophilic substituents.

Animals↗
PubMed1989

[Evaluation of excised loach skin for studies on transdermal permeation of drugs in vitro].

Transdermal permeation of drug across the excised skin of Asian pond loach (Misgurnus anguillicaudatus Cantor) was studied in vitro. Ten kinds of drugs, D-glucose, L-glucose, sucrose, salicylic acid, cefazolin, urea, antipyrine, naphazoline, propranolol and enviomycin were permeated through the excised loach skin, whereas dextran, a polysaccharide, could not be permeated through the skin. The observed transdermal flux (J), the slope of the line obtained from plots of the cumulative amount of drug permeated vs. time, increased as the drug concentration in the donor compartment solution (50----300 mM), as the temperature of the skin (test solution) increased (4----37 degrees C), or as the molecular weight of compound decreased. These results suggested that the transport of drug across the loach skin was due to the passive diffusion mechanism. The effect of pH on the permeation of drug could not be elucidated since the loach skin was drastically impaired below pH 5.0. The J values of antipyrine and naphazoline varied in proportion to the drug concentration in the donor compartment solution at time zero (C0). The permeability constants (Kp, cm.h-1) of antipyrine and naphazoline were 12.9 x 10(-2) and 9.2 x 10(-2), respectively. However, the J values of salicylic acid and urea were not proportional to C0 in high concentration (300 mM). Probably, these results were related to the irritative effect of salicylic acid or urea on the skin.

Animals↗
PubMed2000

[FOITS (fast optical in vivo topometry of human skin): new approaches to 3-D surface structures of human skin].

FOITS (Fast Optical In-vivo Topometry of human Skin) is a new technique for the three-dimensional analysis of the microstructures of the skin. Based on the surface roughness standards used in the metal-working industry, it uses computer-assisted strip analysis to process information gathered from high-speed, non-contact scanning. It is possible to visualise the mathematical data in 3D form. So far, surface relief parameters have had to be acquired indirectly by first making silicone casts of the skin and then digitalising them with image analysis, mechanical scanners or, more recent, laser profilometry and confocal microscopy. We selected the roughness parameters Ra, Rz and Rmax (DIN defined) and "positive" and "negative" volume to describe the skin surface. In 40 healthy volunteers we were able to define significant intra-individual differences in these roughness parameters, which were correlated with the location of the area of skin being scanned (p < 0.05). When healthy areas of skin were compared with areas of chronic eczema in 10 patients with neurodermatitis the differences in the above-mentioned roughness parameters were just as striking (p < 0.05). In patients with chronic atopic eczema there was a statistically significant correlation between changes in the parameters "positive" and "negative" volume, and the smoothing of the skin seen after 14 days of treatment with standard ointments (p < 0.02). Apart from its industrial uses, we see potential applications for FOITS in the investigation of quantitative and qualitative aspects of aging processes, physiological and pathological processes in the skin, and the effect of topical preparations applied to the skin.

Adolescent↗
PubMed2003

Delivering vaccines into the skin without needles and syringes.

The skin is a highly accessible organ and due to the presence of powerful antigen-presenting cells in the epidermis, it functions as an immune barrier. This makes the skin an attractive route for potential delivery of vaccines by painless and user-friendly methods without the requirement of needles and syringes. This article reviews current attempts to administer vaccines into the skin and discusses some of the scientific issues related to the emerging delivery technologies.

Administration, Cutaneous↗
PubMedDate not supplied

Cancer epidemiology and the workplace.

Occupational exposure occurs most frequently through direct contact with carcinogenic agents, with any of their active metabolites during absorption (skin, respiratory tract); or during excretion (urinary tract). In the USA, from 2-8% of cancer are attributed to this circumstance. In developing countries emphasis should be made on prevention measures of possible carcinogenic exposure factors, with three basic premises: a) identify exposure markers (biological monitoring); b) identification of high risk subjects, presumable before exposure occurs, and c) early identification of signs of sickness (medical surveillance). This article proposes that, in theory, all occupational cancer can be prevented.

Carcinogens↗
PubMed1989

Review of tissue penetration and clinical efficacy of enoxacin in skin and skin structure infections and in osteomyelitis.

Enoxacin achieves a high penetration into skin tissue and blister fluid, reaching a maximum serum concentration (Cmax) of 3.7 mg/L at a time to reach maximum concentration (tmax) of 1.9 hours and a blister-fluid Cmax of 2.9 mg/L at a tmax of 3.7 hours after an oral dose of 600 mg. The half-life of enoxacin is 6.2 hours in serum and 7.2 hours in blister fluid. In a multicentre, open, non-comparative trial, clinical cure or improvement in skin or skin structure infections was achieved after oral administration of enoxacin 200 to 600 mg twice daily in 88% of 196 evaluable patients. Overall satisfactory bacteriological response was obtained in 76% of patients. In a multicentre, randomised, double-blind trial comparing oral enoxacin 400 mg twice daily with cephalexin 500 mg twice daily, satisfactory clinical outcome was achieved in 92% of 73 evaluable patients receiving enoxacin and in 99% of 72 evaluable patients receiving cephalexin. Furthermore, there was no statistically significant difference between the bacteriological efficacy of the 2 agents. In 3 single-centre trials, satisfactory clinical results were achieved in 75 to 100% of patients, and satisfactory bacteriological results occurred in 47 to 76% of patients after administration of oral enoxacin 400 mg twice daily for 7 to 14 days. In vitro uptake of enoxacin in bone leads to a concentration of 300 micrograms/g, with 83% being retained by bone after 3 washings with saline at pH 7.2. Clinical trials involving oral enoxacin in osteomyelitis are currently under way.

Enoxacin↗
PubMed1977

Vitamin A acid: a review of its pharmacological properties and therapeutic use in the topical treatment of acne vulgaris.

Vitamin A acid (retinoic acid: tretinoin) is a vitamin A derivative used in the topical treatment of acne. It acts by 'unseating' comedones, improvement developing slowly over a period of 2 to 3 or more months, and is also said to prevent the formation of new lesions. About three-quarters of patients with acne vulgaris benefit from treatment. In controlled studies, results achieved after a 3 to 4 months course of treatment were superior to those with sulphur-resorcinol-salicylic acid. When compared with benzoyl peroxide, results were variable and appear to depend on the length of treatment, the types of formulations used, and the concentrations compared. Application of vitamin A acid should be continued until the patient has been free of new lesions for several months. Further continued application at a less frequent interval or using a less active dosage form may help to prevent exacerbations of acne. A systemic antibacterial agent such as tetracycline can be given as well as in patients with moderate to severe lesions. Vitamin A acid is used in conjunction with gentle washing (to remove surface oil) but should be applied to a dry skin to avoid unnecessary irritation. Patient education and encouragement are crucial during the initial phase of treatment when microcomedones may be converted to pustules prior to desquamation.

Acne Vulgaris↗
PubMed1978

Econazole: a review of its antifungal activity and therapeutic efficacy.

Econazole1 is a recently introduced imidazole antifungal agent which is very closely related structurally to another imidazole derivative, miconazole. For local application the nitrate salt of econazole is used, while in preliminary investigations of systemic use in a few patients econazole base has been administered orally or intravenously. In uncontrolled studies in large numbers of patients, econazole nitrate has been administered topically in the treatment of dermatomycoses due to a wide variety of fungi, and vaginally in the treatment of vaginal candidosis; but it has not been compared with any other antifungal drug in controlled therapeutic trials in mycoses of the skin and has only been compared with nystatin in a few patients with vaginal candidosis. Until adequate comparative studies are done the relative place of econazole in the treatment of dermatomycoses and vaginal condidosis, compared with traditional antifungal agents and with other imidazole derivatives such as miconazole or clotrimazole, cannot be clearly stated. Nevertheless, econazole nitrate is an effective antifungal drug. In dermatological studies about 90% of a large number of patients were cured, often after a relatively short treatment period (2 to 6 weeks, as occurs with other imidazole antifungal agents). The cure rate was only slightly lower (about 85%) in patients with severe mycoses of many years' duration than in those whose infections were of more recent onset. In vaginal candidosis a 3-day treatment regimen using a 150mg suppository once daily was only slightly less effective (85% mycological cure rate) than a 15-day regimen using a 50mg dose (suppository or cream) once daily (90% cure rate). A 3 to 5 day 'higher' dose regimen was slightly more effective than a standard 15-day regimen of nystatin vaginal inserts in a small group of patients with vaginal candidosis. The convenience of the higher-dose shorter term regimen would likely be an important advantage to most patients. Whether other agents useful in vaginal candidosis would be as effective as econazole were they to be used in this way, has not been determined. Topical or intravaginal econazole nitrate has usually been well tolerated, side effects being limited to local irritation in about 1 to 4% of patients in most studies.

Adult↗
PubMed1984

Isotretinoin. A review of its pharmacological properties and therapeutic efficacy in acne and other skin disorders.

Isotretinoin is a new orally active retinoic acid derivative for the treatment of severe refractory nodulocystic acne. The pharmacological profile of isotretinoin suggests that it acts primarily by reducing sebaceous gland size and sebum production, and as a result alters skin surface lipid composition. Bacterial skin microflora is reduced, probably as a result of altered sebaceous factors. Isotretinoin 1 to 2 mg/kg/day for 3 to 4 months produces 60 to 95% clearance of inflammatory lesions in patients with severe, recalcitrant nodulocystic acne, with evidence of continued healing and prolonged remissions in many patients after treatment withdrawal. Doses as low as 0.1 mg/kg/day have also proven successful in the clearance of lesions; however, with such low doses the duration of remission after discontinuation of therapy is usually shorter. Encouraging results have also been seen in small numbers of patients with rosacea, Gram-negative folliculitis, Darier's disease, ichthyosis and pityriasis rubra pilaris, the response in keratinising disorders resembling that with the related drug etretinate. While long term follow-up studies in these patients have not been reported, prolonged remission after withdrawal of isotretinoin in disorders of keratinisation is unlikely, as with other drugs used in these conditions. Isotretinoin is only partially effective in psoriasis, in contrast to etretinate which is very effective in psoriasis but ineffective in severe acne. Some encouraging results have also been reported with isotretinoin in patients with squamous and basal cell carcinomas, but isotretinoin has proven unsuccessful in non-squamous cell epithelial and non-epithelial cancer. Side effects affecting the mucocutaneous system occur in nearly all patients receiving isotretinoin, but rarely lead to drug withdrawal. Raised serum triglyceride levels are also commonly reported. The possibility of long term spinal or skeletal bone toxicity may restrict the use of isotretinoin in severe disorders of keratinisation requiring prolonged administration. Isotretinoin is strictly contraindicated in women of childbearing potential due to its severe teratogenic properties, unless an effective form of contraception is used. Thus, isotretinoin offers an effective advance on the treatment options available in a difficult therapeutic area - those patients with severe, nodulocystic acne not responding to 'traditional' therapy.

Acne Vulgaris↗