Separation of epidermis from dermis in the Rhesus monkey

Frank, John D.; Manson, Jeanne M.; Cartwright, Mark E.

doi:10.1111/j.1600-0625.1995.tb00228.x

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…Tissues collected included skin from five different skin sites (neck, dorsolateral back, ventral abdomen, left and right inguinal regions, and left and right axillary regions), lymph nodes (left and right inguinal, prescapular, and submandibular nodes), liver (left, right, and middle lobes), kidneys (cortical and medullary regions of the left and right kidneys), gall bladder, heart (left and right ventricular walls and intraventricular septum), lungs (cranial, middle, and caudal lobes), brain (cerebrum, thalamus, midbrain, and cerebellum), and feces (sample from upper colon). Epidermis was separated from dermis prior to ICP-MS analysis using the dry heat method described by Frank et al (1995). According to this method, skin is heated between two blocks at 63°C for 2 min and the two layers are separated using titanium-free instruments.…”

Section: Methodsmentioning

confidence: 99%

Lack of Significant Dermal Penetration of Titanium Dioxide from Sunscreen Formulations Containing Nano- and Submicron-Size TiO2 Particles

Sadrieh

Wokovich

Gopee

et al. 2010

Toxicological Sciences

275

168

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Titanium dioxide (TiO(2)) is included in some sunscreen formulations to physically block ultraviolet radiation. A dermal penetration study was conducted in minipigs with three TiO(2) particles (uncoated submicron sized, uncoated nano-sized, and dimethicone/methicone copolymer-coated nanosized) applied 5% by weight in a sunscreen. These and control formulations were topically applied to minipigs at 2 mg cream/cm(2) skin (4 applications/day, 5 days/week, 4 weeks). Skin (multiple sites), lymph nodes, liver, spleen, and kidneys were removed, and the TiO(2) content was determined (as titanium) using inductively coupled plasma mass spectroscopy. Titanium levels in lymph nodes and liver from treated animals were not increased over the values in control animals. The epidermis from minipigs treated with sunscreens containing TiO(2) showed elevated titanium. Increased titanium was detected in abdominal and neck dermis of minipigs treated with uncoated and coated nanoscale TiO(2). Using electron microscopy-energy dispersive x-ray analysis, all three types of TiO(2) particles were found in the stratum corneum and upper follicular lumens in all treated skin samples (more particles visible with coated nanoscale TiO(2)). Isolated titanium particles were also present at various locations in the dermis of animals treated with all three types of TiO(2)-containing sunscreens; however, there was no pattern of distribution or pathology suggesting the particles could be the result of contamination. At most, the few isolated particles represent a tiny fraction of the total amount of applied TiO(2). These findings indicate that there is no significant penetration of TiO(2) nanoparticles through the intact normal epidermis.

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Section: Methodsmentioning

confidence: 99%

Lack of Significant Dermal Penetration of Titanium Dioxide from Sunscreen Formulations Containing Nano- and Submicron-Size TiO2 Particles

Sadrieh

Wokovich

Gopee

et al. 2010

Toxicological Sciences

275

168

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“…The skin sections with 9 mm diameter were punched from a piece of human cadaver skin, using a cork borer. The epidermis and the dermis were separated for each section, using the modified heat separation method (23,24). Both the epidermis and the dermis, for each skin section, were separately treated with 50 μL of the drug solutions for 4 h in microcentrifuge tubes.…”

Section: The Recovery Of Cpo From Epidermis and Dermismentioning

confidence: 99%

“…The skin used in the finite dose permeation study was further analyzed for drug content by separating the epidermis and the dermis using a modified heat separation method (23,24). Post the finite dose skin permeation experiment, the skin was dismounted from the Franz cell and washed with Nanopure water thrice on both the epidermal and the dermal sides to remove any surface drug.…”

Section: Finite Dose Skin Penetration Of Cpomentioning

confidence: 99%

A Preformulation Strategy for the Selection of Penetration Enhancers for a Transungual Formulation

2013

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Onychomycosis is associated with the cutaneous fungal infection of the nail and the nail folds (skin surrounding the nail). It is therefore important to target drug delivery into the nail folds along with nail plate and the nail bed. Systematic and strategic selection of the penetration enhancers specific for the skin and the nail is discussed. Twelve penetration enhancers were screened for their ability to improve solubility, in vitro nail penetration, in vitro skin permeation, and in vitro skin penetration of the antifungal drug ciclopirox olamine. In contrast to transdermal drug delivery, the main selection criteria for skin penetration enhancer in topical drug delivery were increased drug accumulation in the epidermis and minimal permeation across the skin. Thiourea improved the solubility and nail penetration of ciclopirox olamine. It also showed enhancement in the transungual diffusion of the drug. Propylene glycol showed a 12-fold increase in solubility and 3-fold increase in epidermal accumulation of ciclopirox olamine, while minimizing the transdermal movement of the drug. Thiourea was the selected nail permeation enhancer and propylene glycol was the selected skin penetration enhancer of ciclopirox olamine. A combination of the selected enhancers was also explored for its effect on drug delivery to the nail and nail folds. The enhancer combination reduced the penetration of ciclopirox in the skin and also the permeation through the nail. The proposed preformulation strategy helps to select appropriate enhancers for optimum topical delivery and paves way towards an efficient topical formulation for passive transungual drug delivery.

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“…Stratum corneum is usually prepared by immersing full-thickness skin in hot water for brief seconds. This technique is also known as heat-separated epidermis (HSE) [ 4 , 6 , 7 , 8 , 9 ]. Other approaches to isolate skin layers include chemical or enzymatic separation, but those are rarely used techniques.…”

Section: Introductionmentioning

confidence: 99%

Reconstructed Human Epidermis: An Alternative Approach for In Vitro Bioequivalence Testing of Topical Products

Agonia

Palmeira‐de‐Oliveira

Cardoso³

et al. 2022

Pharmaceutics

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The use of in vitro human skin permeation tests is of value when addressing the quality and equivalence of topical drug products in Europe and the US. Human skin is the membrane of choice for these studies. The use of human skin as a membrane is hindered by limited access, high variability of results, and limited applicability for drugs with low skin permeability. Reconstructed human epidermis (RhE) models are validated as skin surrogates for safety tests and have been explored for percutaneous absorption testing. Clotrimazole poorly permeates human skin and is widely available for topical treatments. In this study, clotrimazole creams were used to test the ability of RhE to be used as biological membrane for bioequivalence testing, based on the Draft Guideline on Quality and Equivalence of Topical Products (CHMP/QWP/708282/2018) using a discriminative and modified in vitro permeation test (IVPT). To fulfill the validation of a discriminatory method, Canesten® 10 mg/g cream was compared with a test product with the same drug strength, along with two “negative controls” dosed at a 50% and 200% drug strength. Products were compared in finite dose conditions, regarding maximal flux (Jmax) and the total amount of drug permeated (Atotal). The results showed the discriminatory power of the method among the three drug strengths with no interference of the placebo formulation. The study design and validation complied with the requirements established in the guideline for a valid IVPT. This new test system allowed for the equivalence comparison between test and comparator product. Higher permeability of the RhE compared to human skin could be observed. This arose as a strength of the model for this modified IVPT bioequivalence testing, since comparing permeation profiles among products is envisaged instead of drawing absolute conclusions on skin permeation extent. These results may support the acceptance of RhE as biological membranes for modified IVPT in bioequivalence testing of topical products.

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Separation of epidermis from dermis in the Rhesus monkey

Cited by 4 publications

References 13 publications

Lack of Significant Dermal Penetration of Titanium Dioxide from Sunscreen Formulations Containing Nano- and Submicron-Size TiO2 Particles

Lack of Significant Dermal Penetration of Titanium Dioxide from Sunscreen Formulations Containing Nano- and Submicron-Size TiO2 Particles

A Preformulation Strategy for the Selection of Penetration Enhancers for a Transungual Formulation

Reconstructed Human Epidermis: An Alternative Approach for In Vitro Bioequivalence Testing of Topical Products

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