Structure of skin
- 1. Presented by Aishwarya C. Patil M.Pharm (First Year) Dept.of Pharmaceutics Rajarambapu College Of Pharmacy Kasegaon.
- 2. TDDS are topically administered medicaments in the form of patches that deliver drugs for systemic effects at predetermined and controlled rate. Transdermal patch is an adhesive patch, that has a coating of medicine (drug), that is placed on the skin to deliver specific dose of the medicine, into the blood over a period of time. 15/11/2017 2
- 3. Transdermal therapeutic are defined as self contained dosage form which when applied to the intact skin deliver the drugs, through the skin, at a controlled rate to the systemic circulation. 15/11/2017 3
- 4. Avoidance of first-pass effect Long duration of action Comparable characteristics with IV infusion No interference with gastric and intestinal fluids Suitable for administered of drug having- • Very short half-life, e.g. nitroglycerine. • Narrow therapeutic window. • Poor oral availability. 15/11/2017 4
- 5. Poor diffusion of large molecules Skin irritation Requires high drug load Unsuitable –If drug dose is large Absorption efficiency is vary with different sites of skin. 15/11/2017 5
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- 7. The skin is the largest organ of the body, with a total area of about 20 square feet. The skin protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold. It covers an area of about 2m2 and 4.5-5 kg i.e. about 16% of total body weight in adults. Thickness is in range of 0.5mm (on eyelids ) to 4.0mm ( on heels ) 15/11/2017 7
- 8. The skin has three layers: 1) Epidermis 2) Dermis 3) Hypodermis or Fat layer ( subcutaneous layer) 15/11/2017 8
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- 10. Stratum Cornium- consists of 25 to 30 layers of flattened dead keratinocytes. Which makes it water repellent. Stratum Granulosm- consists of 3 to 5 layers. It contains granules known as Keratohyalin. These granules release Lipid rich secretion, which acts as the water repellent. Stratum Spinosum- contains 8 to 10 layers of cells and it is closely arranged. Stratum Basal- consists of single layer of cubical or columnar keratinocytes. 15/11/2017 10
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- 12. The stratum basale is a single layer of cells primarily made of basal cells. A basal cell is a cuboidal-shaped stem cell that is a precursor of the keratinocytes of the epidermis. The first is a Merkel cell, which functions as a receptor and is responsible for stimulating sensory nerves that the brain perceives as touch. The second is a melanocyte, a cell that produces the pigment melanin. 15/11/2017 12
- 13. The stratum spinosum is composed of eight to 10 layers of keratinocytes, formed as a result of cell division in the stratum basale. In the keratinocytes of this layer is a type of dendritic cell called the Langerhans cell, which functions as a macrophage by engulfing bacteria, foreign particles, and damaged cells that occur in this layer. 15/11/2017 13
- 14. The stratum granulosum has a grainy appearance due to further changes to the keratinocytes as they are pushed from the stratum spinosum. The cells (three to five layers deep) become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin, which is fibrous, and keratohyalin, which accumulates as lamellar granules within the cells. 15/11/2017 14
- 15. The stratum lucidum is a smooth, translucent layer of the epidermis. located just above the stratum granulosum and below the stratum corneum. The keratinocytes that compose the stratum lucidum are dead and flattened. protein rich in lipids, derived from keratohyalin, which gives these cells their transparent appearance and provides a barrier to water. 15/11/2017 15
- 16. The stratum corneum is the most superficial layer of the epidermis. A keratinocytes is a cell that manufactures and stores the protein keratin. Keratin is an intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties. There are usually 15 to 30 layers of cells in the stratum corneum. This dry, dead layer helps prevent the penetration of microbes and the dehydration of underlying tissues, and provides a mechanical protection against abrasion for the more delicate, underlying layers. 15/11/2017 16
- 17. Composed of strong connective tissue containing collagen and elastic fibers, hence it can easily stretch and recoil easily. Blood vessel, nerves gland and hair follicles are embedded in this layer. 15/11/2017 17
- 18. The papillary layer is made of loose, areolar connective tissue, which means the collagen and elastin fibers of this layer form a loose mesh. This superficial layer of the dermis projects into the stratum basale of the epidermis to form finger- like dermal papillae. Within the papillary layer are fibroblasts, a small number of fat cells (adipocytes), and an abundance of small blood vessels. 15/11/2017 18
- 19. Underlying the papillary layer is the much thicker reticular layer, composed of dense, irregular connective tissue. This layer is well vascularized and has a rich sensory and sympathetic nerve supply. Elastin fibers provide some elasticity to the skin. Collagen fibers provide structure and tensile strength, with strands of collagen extending into both the papillary layer and the hypodermis. 15/11/2017 19
- 20. It is also called as Hypodermis. It is made up of loose connective tissue, including Adipose tissue. This helps to insulate the body by monitoring heat gain and heat loss. The hypodermis consists of well-vascularized, loose, areolar connective tissue and adipose tissue, which functions as a mode of fat storage and provides insulation and cushioning for the integument. 15/11/2017 20
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