[TERM2:L2]: Transdermal Drug Delivery Systems and Technologies Flashcards
Absorption of substances from outside the skin to positions beneath the skin, including entrance into the bloodstream.
Percutaneous Absorption
the drug incorporated in an appropriate vehicle must
interface the skin surface in sufficient concentration
Right Vehicle
as concentration of the drug substance in the
vehicle increases, the amount of drug percutaneously absorbed increases Factors Affecting Percutaneous Absorption
Drug Concentration
more is absorbed through the percutaneous absorption when the drug substance is applied to a larger surface area
Surface Area
the drug substance should have a greater physicochemical attraction to the skin than to the vehicle
Physicochemical Attraction
same degree of solubility of the drug both in oil and
water is essential for effective percutaneous absorption Factors Affecting Percutaneous Absorption
Degree of Solubility
drug absorption appears to be enhanced from vehicles
that easily cover the skin surface, mix readily with the sebum and bring the
drug into contact with the tissue cells for absorption
Nature of Vehicle
vehicle that increase the amount of moisture
imbibed by the skin generally favor the percutaneous absorption of the
drug
Moisturizing Vehicle
this appears to increase the rate of passage of all
substances that penetrate the skin Factors Affecting Percutaneous Absorption
Skin hydration
hydration of the skin is influenced not only by the type of vehicle but also by the absence or presence of a bandage over the medicated application. Occlusive bandage is more effective
Bandage
The amount of rubbing in or inunctions of the topical
application will have a bearing on the amount of drug absorbed Factors Affecting Percutaneous Absorption
Skin stimulation
thin horny layer absorption has greater percutaneous
absorption of the drug
Horny Layer
period of time the medicated application is permitted to remain in contact with the skin. The longer the period of time, the greater is
the absorption
Length of Time
Factors Affecting Percutaneous Absorption
- Right Vehicle
- Drug Concentration
- Surface Area
- Physicochemical Attraction
- Degree of Solubility
- Nature of Vehicle
- Moisturizing Vehicle
- Skin hydration
- Bandage
- Skin stimulation
- Horny Layer
- Length of Time
a film of emulsified material composed of a
complex mixture of sebum, sweat and
desquamating horny layer.
Skin
a layer of dead epidermal cells, situated directly beneath the emulsified film.
HORNY LAYER OR STRATUM CORNEUM
a 10- to 15-millimicron thick layer of flat partially desiccated, non-living tissue
which forms the skin’s outermost surface. * The percutaneous absorption of a drug generally results from the direct penetration of the drug through this layer.
HORNY LAYER OR STRATUM CORNEUM
Being keratinized tissues, it behaves as a semi-permeable artificial membrane and drug molecules penetrate by passive diffusion.
HORNY LAYER OR STRATUM CORNEUM
The lipid component of this tissue is considered the
factor directly responsible for low penetration of drugs
HORNY LAYER OR STRATUM CORNEUM
Located beneath the horny layer
If the skin is intact, the main site for the penetration of a drug is
through this tissue
BARRIER LAYER OR LIVING EPIDERMIS OR STRATUM
GERMINATIVUM
When the drug reaches the vascularized dermal layers, it becomes available for absorption into the general circulation
DERMIS OR TRUE SKIN
Histological Divisions of Skin
- HORNY LAYER OR STRATUM CORNEUM
- BARRIER LAYER OR LIVING EPIDERMIS OR STRATUM
GERMINATIVUM - DERMIS OR TRUE SKIN
rise from the subcutaneous fat tissue into the dermis up to the epidermis
BLOOD CAPILLARIES AND NERVE FIBERS
present in the subcutaneous tissue yield their products by way of sweat ducts which find their way to the surface of the skin
SWEAT GLANDS
