PHAR 300 Lecture 4: 4 PHAR300 - Cosmetics
7 Jun 2018
School
Department
Course
Professor
PHAR300
Drugs, cosmetics - skin, hair and teeth
Initially, drugs and cosmetics were 2 separated domains
-e.g. cream to treat baldness is more than just a cream -> has a biological action
-every time we brush our teeth -> use drugs
-some are classified just as cosmetics (only sit at the surface of the skin)
Reasons for why people use and buy cosmetics
-scale on how people describe themselves : looking handsome, beautiful, very attractive,
interesting looking…
-most people (males and females) put themselves in the middle, a small fraction feels that they
look better than the average
Skin
-largest organ -> people apply
various creams and lotions
from the beginning of their
life
-outer layer : epidermis ;
deeper layer : dermis
-various structures within the
dermis : hair follicle,
sebaceous glands that secrete
sebum which coats the surface
of the skin keeping it moist,
blood supply (ends at the base
of the epidermis, blood flow
can increase…), sweat glands
(cool the body), adipose tissue
at the bottom, sensory nerves
-function of the skin : protect
us (external coating), sends
impulses => can be aware of what happens in our surroundings
-amount and type of melanin varies
-melanocytes at the base synthesise the pigments, eject it -> taken up by the surrounding
keratinocyte, which is what gives the skin its color
-injury by UV light stimulates melanocytes to increase production of melanin (= tan) =>
protects against more injury
-special sense receptors in the skin
-on the surface -> very capable of healing -> if we just injure the epidermis, basal cells are able to
reproduce => fixes itself
-skin is not the same everywhere -> structure adapted to location (thickness is different) ->
different absorption depending on the site of the body we are looking at
-normally things don’t pass through the skin, they have to break the external barrier of the skin
-e.g. baby lotion -> says «!therapy!» but not really the definition
-behind the ear = very good place of absorption because very thin skin (e.g. anti-nausea drug)
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-photosensitivity : some drugs will sensitise the skin to the action of UV light -> antibiotics do
this, diuretics, antipsychotics, NSAIDS, many plants and herbal mixtures… => normal exposure
to sun can lead to various lesions and skin damage
Psoriasis : hyper-proliferation of keratinocyte
-abnormal immunological reaction of the skin
-treatment = drug
Cosmetics vs. cosmeceuticals
-cosmeceuticals : describe components that we put on our skin that have an active drug in them
and have been shown by various studies to have some effectiveness, tested
-very big industry now, expands all the time
-people want to see the evidence that the product works
-market for these products is very important now
-change some of the skin damage, reverse skin damage due to smoking, UV exposure…
Sunscreens
-prevent skin damage
-sun is damaging to the skin
-UVA and UVB that are able to penetrate the skin
-UVA goes deeper (dermis, 320-400nm wavelength), UVB more on the surface (epidermis,
290-320nm wavelength)
-both cause skin damage, including skin cancer
-tanning is a reaction to an injury
-particularly important when on the water (because of reflection)
-people are more or less vulnerable : melanin protects us, to some extend ; most vulnerable =
very light skin and have freckles (melanin is concentrated there so space between is very
vulnerable), especially during childhood (every sunburn during childhood increases a lot the
chance to have skin cancer
-photo ageing -> due to sun damage, causes wrinkles
-pigment changes, damaged blood vessels…
-skin cancer : basal cell carcinoma ; melanoma (most lethal)
-how to rate the effectiveness of sunscreen : SPF is a measure of efficacy (parallel to ED50…) ->
allows to tell how effective the application will be (SPF50 : can stay out 50 times longer)
-many different compounds have been developed -> some block UVA and some UVB, a few
block both (called broad spectrum)
-by broad spectrum (blocks UVA and UVB) SPF 15-30 ; waterproof if swimming
Retinoids
-acne :
-increased production of keratin in the epidermis ->
tends to block the duct
-increased amount of sebum -> blocks the duct
-inflammation in the sebaceous gland which can rupture
in the surrounding tissues
-growth of microorganisms in the duct -> trigger of
inflammation
-oxidised sebum (blackhead, closed) -> not dirt, sebum
and keratin are just stuck on the opening of the follicle
-trapped sebum along with keratin
-bacteria grow and leukocytes come in to deal with the
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Document Summary
Initially, drugs and cosmetics were 2 separated domains. E. g. cream to treat baldness is more than just a cream -> has a biological action. Every time we brush our teeth -> use drugs. Some are classi ed just as cosmetics (only sit at the surface of the skin) Reasons for why people use and buy cosmetics. Scale on how people describe themselves : looking handsome, beautiful, very attractive, Most people (males and females) put themselves in the middle, a small fraction feels that they interesting looking look better than the average. Largest organ -> people apply various creams and lotions from the beginning of their life. Outer layer : epidermis ; deeper layer : dermis. Function of the skin : protect us (external coating), sends impulses => can be aware of what happens in our surroundings. Melanocytes at the base synthesise the pigments, eject it -> taken up by the surrounding.
