1) Transdermal drug delivery systems (TDDS) are patches that deliver drugs systemically through the skin at controlled rates for predetermined periods of time. 2) TDDS offer advantages over other delivery methods like avoidance of first-pass metabolism, long duration of action, and suitability for drugs with short half-lives or narrow therapeutic windows. 3) However, TDDS also have limitations like poor diffusion of large molecules, potential for skin irritation, and requirement of high drug loads. Absorption also varies between different skin sites.

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.
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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.
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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.
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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.
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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 )
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8.  The skin has three layers:
1) Epidermis
2) Dermis
3) Hypodermis or Fat layer ( subcutaneous layer)
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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