Dermatological vehicle additives Flashcards
What are common additives to dermatological vehicles
- Humectants
- increase hydration of the skin at low conc
- withdraw moisture at high conc
- prevent prodcut from drying out
- propylene glycol, glycerol, PEG
- Levigating agents
- liq to aid in incorporation and particle size reduction of powder -> oint
- maximum 5% of final formualtoin
- mineral oil, glycerol
- Penetration enhancers
- Temorarily increase the permeability of the skint o allow drug molecules to pass
- ex: chemical permeation enhancers, specialized delivery systems
- Temorarily increase the permeability of the skint o allow drug molecules to pass
- Antioxidants
- Preservatives
what are the properties of penetration enhancers
- Pharmacologically inert
- Non-toxic, non-irritating, non-allergenic
- Immediate and predictable effect
- Immediate recovery of the barrier property of the skin after removal of the agent •Should not cause loss of body fluids, electrolytes or other endogenous materials •Compatible with drugs and excipients
- Good drug solvent
- Cosmetically acceptable (good spreadability and “feel”)
- Readily formulated into the various types of topical preparations
- Odourless, tasteless, colourless and inexpensive
ex of chemical permeation enhancers
Sulfoxides (DMSO)
Azone
Pyrrolidones
Fatty acids (Oleic acid)
Alcohols, glycols (ethanol, propylene glycol)
Surfactants (SDS, Tween 80)
Urea
Terpenes
Phospholipids
Biochemical enhancers
delivery ststems that act as peneation enhancers
Liposomes and other lipid-based systems
Nanoparticles
occlusion as method to enhance percutaneous absorption
Formation of an impermeable layer on the skin to prevent evaporation of water.
Can be accomplished by plastic wrap (over applied ointment)
Increased hydration (by preventing evaporation of water from the skin)
Softening of the skin (emollient action)
ex of antioxidants
Butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) Ascorbic acid, ascorbyl palmitate Hydroquinone
Tocopherol
Sulfites, bisulfites
ex of antimicrobial preservatives
*topical baes with aqueous phases, carbohydrates and proteins are readily attacked by bacteria and fungi
alcohols: ethanol, isopropanol
acid: benzoic acid
Mercurials; thimerosal
Phenols; phenol, cresol
p-hydroxybenzoates: methyl, propyl, butylparaben
Quaternary ammonium compounds:benzalkonium chloride, cetrimide
treatment of acne
- chronic inflammation of pilsosebaceous unit, inc sebum production
- free fatty acids produced by P acnes bacteria
- Therapy
- Bacteriostatics: benzoyl peroxide
- topical antibiotics
- exfoliants: sulfur, resorcinaol, tretinoin, salicylic acid, benzoyl perioxide
- Types of bases: liquids, gels, creams, o/w emulsions, ]NO OCCULSIVE BASES
what type of bases to avoid for treatment of acne
occlusive bases
alopecia
- Pathophysiology
- natural or abnormal loss of hiar on scalp
- family history
- angrogenic influences
- aging
- systemic disorders
- natural or abnormal loss of hiar on scalp
- Appearance
- baldness, totalid (no hair) or areata (patchy hair loss
- Treatment
- no satisfactory treatment (possibly Minoxidil/Rogaine®)
types of bases used to treat alopecia
water or alcohol based liquids
gels
creams
eczema
- pathophysiology
- superficial inflammation of skin
- atopic dermatitis (allergic condition)
- contact dermatitis (delaye hypersensitivity rxn)
- superficial inflammation of skin
- Appearance
- intense itching, erthema, swelling edema, oozing, scaling
- Therapy
- Emollients
- Astringents
- Antipruritics
- Topicalcorticosteroids
types of bases used to treat excema
creams
lotions
try to avoid occlusion
psoriasis
- pathophysiology
- chonric inflammatory skin disease
- Appearance
- red patches on scalp or extremities
- lesions covered with silver white scales will bleed if removed
- therapy
- emollients (hydration)
- keratolytics (remove scales)
- corticosteriods (treat inflammation)
types of abses used to treat psoriasis
occlusive (the more the better) -> hydrocarbons, silicon bases
- creams
- ointments with plastic wrap (INC hydration)
Urticaria
- Pathophysiology
- vascular reactionto insect bites, diet or drugs
- Appearance
- wheals surrounded by halo accompanied by severe tiching and burning
- therapy
- topical astringents
- anti-inflammatory lotions
- anti-histamines
types of bases used to treat urticaria
non-occlusive
gels
shake lotions (cool — relieve burning and itching)
creams
herpes simplex
- pathophysiology
- recurrent viral infection of the skin and mucous membranes
- Appearance
- vesicles appearing in clusters on erythematous base
- therapy
- topcial antiviral prep
- lotetions containing camphor and tannic acid
types of bases used to treat herpes simplex
non-occlusive
liquid lotions
PEG
gels
corns and calluses
- Pathophysiology
- corns: raised conical hyperkaratinous lesions extending down to dermis and pressing inward on nerve endigns
- causing paina nd irritation
- calluses: circumsized thickness of skin due to pain and pressue
- corns: raised conical hyperkaratinous lesions extending down to dermis and pressing inward on nerve endigns
- Appearance
- dry thickings of skin on or between toes
- Therapy
- remove causative factor
- keratolytics (salicylic acid> 10%)
- caustics (lactic acid, tricholoroacetic acid emulsions)
- emollients
types of bases used to treat corns and calluses
- occlusive - the more the better (easier to remove by abrasion)
- collodions (liquid with organic solvents + polymer that deposits on skin)
atheltes foot
- pathophysiology
- superficial fungal infection of the skin
- appearance
- small blisters between toes, cracks, redness, maceration, itching, burning
- Therapy
- thorough dry feet after shower/bath
- topical antifungal creams
types of bases used to treat athletes foot
non-occlusive
o/w creams
Define shunt route of drug permeation into/through skin?
Shunt route = absorption through the appendages
Define acid mantle. Win this context, what is the significance of pH 5.5?
Acid mantle pH 4.2 - 5.6 → bacteriostatic and fungistatic secretions (short chain fatty acids from sebaceous and eccrine sweat glands)
– formulations with pH 5.5 are said to be the most compatible with the skin
The skin is an important heat barrier; what is the consequence of heat or cold exposure on the skin vasculature and percutaneous absorption?
- Heat conservation (vasoconstriction, shivering, goose bumps)
- percutaneous absorption decreases
- Heat loss (vasodilation, skin reddening)
- percutaneous absorption increases
Define ‘sink conditions’
Blood circulation in the dermis maintains sink conditions by taking up drug absorbed into skin into the systemic circulation thereby maintaining high concentration gradient between the formulation and the skin
Define occlusion and its effects on the skin.
Occlusio = formation of an impermeable layer on the skin to prevent evaporation of water.
*Can be accomplished by plastic wrap over generally greasy ointments
Effects:
- > Increased hydration (by preventing evaporation of water from the skin)
- > Enhanced percutaneous absorption
- > Softening of the skin (emollient action)
