Pharmaceutics II: Lecture 1: Topical Dosage Forms

dilwent

Describe the Epidermis:

Non-vascular multilayered structure that varies in thickness; cells within it divide and produce the stratum corneum/horny layer on the surface of the skin (Upper Layer)

Describe the Keratinocyte:

The principle epidermal cell and is lipophilic in nature

Describe the Dermis:

Matrix of connective tissue (elastic) formed from fibrous proteins which are embedded in a semi gel matrix of mucopolysaccharide; nerves, blood vessels and lymphatics traverse the matrix of the layer and skin appendages pierce it; blood supply quickly absorbs compounds passing the epidermis, promoting percutaneous absorption

Describe the Subcutaneous Tissue:

A network of fat cells that act as shock absorber and a thermal barrier

Describe the Sweat Gland:

Produces sweat to regulate body temperature and removal of waste

A topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation and thus helps protect against sunburn

Sunscreen

What is the stratum corneum?

A layer of fully keratinized (Cornified) impermeable dead cells

Describe the Sebaceous Glands:

Produce sebum and are associated with hair follicles

Which skin layer is responsible for the mechanical function of skin?

The Dermis provides the mechanical properties of skin, with the epidermis playing a minor part

Which skin layer is responsible for the protective function of the skin and what are the different aspects within it? (examples: 5)

The Epidermis provides the protective function of skin,

Aspects:

1- Microbiological barrier: sloughing of squames with its

adhering microorganisms.

2- Chemical barrier

3- Radiation barrier

4- Heat barrier and temperature regulation.

5- Electrical barrier

What are the physical properties of the "Stratum Corneum Barrier"? What is the result of these properties on topical formulations?

1- Very high density of cells

2- Low hydration

3- Composed of keratin and lipids

4- Contains intercellular region (lipids and desmosomes)

Therefore the horny layer (SC) is very impermeable to

chemicals and contributes the rate-limiting step in percutaneous absorption

What are the routes for drugs penetration through the skin? (examples: 5)

- Macro Routes for Drug Penetration to the skin:

1- Across the continuous stratum corneum

2- Through the hair follicles with their associated sebaceous glands

3- Via the sweat duct

- Across the continuous stratum corneum:

1- Intercellular

2- Transcellular

What are the main target regions for topical preparations? (examples: 5)

1- Skin surface

2- Horny layer/S.C.

3- Viable epidermis and upper dermis

4- Skin appendages

5- Systemic circulation (Transdermal Route)

Surface treatments: (examples: 2)

1- Insect repellents: Natural/Synthetic

2- Sunscreens

The most common active synthetic ingredient in insect repellents; It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection against mosquitoes and many biting insects

DEET (diethyltoluamide)

Formulation of Natural/Plant-Based Insect Repellents:

Lemon and Eucalyptus oils

What is SPF and how to you calculate it?

Sun Protection Factor (SPF) is a measure of the fraction of sunburn-

producing UV rays that reach the skin; if SPF= X then 1/X of the burning radiation reaches the skin

Stratum Corneum Treatments: (examples: 2)

1- Emollients

2- Sloughing stimulants/Exfoliating agents

Sloughing Stimulants/Exfoliating Agents: (examples: 2)

1- Salicylic acid

2- Uncooked oats

Skin Appendage Treatments: (examples: 4)

1- Anti-perspirants

2- Deodorants

3- Depilatory agents/Hair removal products

4- Topical Anti-biotics or Anti-fungals

Reduce the amount of underarm perspiration from the sweat glands/block sweat gland

Anti-perspirants

Mask and/or reduce axillary odor through the use of an antimicrobial agent with a fragrance

Deodorants

Viable Epidermis and Dermis Treatments Types: (examples: 5)

1- Anti-inflammatory

2- Anesthetic

3- Anti-histamine

4- Anti-biotics

5- Anti-fungals

Systemic Treatments via Percutaneous Absorption: (examples:

1- Motion sickness (hyoscine)

2- Angina (nitroglycerin)

Work on the surface of the skin/the medication does not reach the blood stream; product acts locally

Topical Medications

Topical Medications: (examples: 1)

1- Topical hydrocortisone ointment used to treat skin rashes

Penetrates the skin and enters the blood, thereby allowing effects on the whole body through distribution of medicine via the bloodstream; product acts systemically

Transdermal Medications

Transdermal Medications: (examples: 1)

1- Transdermal nitroglycerin patch (to treat angina) used to relieve heart or chest pain