skin formulations Flashcards
what is the advantage to using skin formulations
can be applied directly to diseased tissue
what is the disadvantage to using skin formulations
skin is designed to be a highly effective barrier- prevent drug entry
what are topical formulations used for
localised action Reach systemic circulation at sub-therapeutic levels
what are transdermal formulations used for
External Skin is not primary target Drugs transport through percutaneous route to systemic circulation
what are some examples of skin formulations
solutions collodion suspensions emulsions
what is the role of emollients
to rehydrate the skin
what is the role of barrier creams
protect skin from irritants
how is ciclosporin cream formulated
W/O
how are NSAID creams formulated
O/W
what are the four types of ointments
hydrophobic fats/oils emulsifying water soluble
what are the 5 dermatological target regions
surface stratum corneum skin appendages viable epidermis-dermis systemic
how does transdermal delivery work
Released drug at rate below maximal rate for controlled systemic therapy
what are the two routes transdermal absorption
Transcellular: through the keratinocytes Intercellular: around keratinocytes via small gaps
what are the advantages of transdermal drug delivery
- Avoids first pass metabolism in liver- Consistent site of absorption - Constant drug input rate - Can stop by removing patch
what are some examples of drugs that are delivered transdermally
- Scopolamine : travel sickness - GTN : angina - Estradiol : HRT - Contraceptives
how are drug candidates decided for transdermal delivery
high potency - only small amount passes through timescale of exposure site/skin condition formulation skin barrier alteration skin hydration
how does skin hydration affect transdermal drug delivery
hydrated skin is more permeable
name 3 drugs formulated for skin that are currently used
glucocorticoids retinoids vitamin d analogues
how do glucocorticoids work topically/transdermally
inhibit release of inflammatory mediators (NFkB), neutrophils activation and mast cell release
what is an example of a mild steroid cream
hydrocortisone
what is an example of a moderate steroid cream
clobetasone
what is an example of a potent steroid cream
betamethasone
what is an example of a very potent steroid cream
clobetasol
what are some side effects of prolonged topical steroid use
rebound atrophy infection rosacea
how do retinoids work topically/transdermally
bind to RXR/RAR nuclear receptors in keratinocytes/sebaceous glands to decrease proliferation and sebum production
side effects of retinoids
dry skin stinging joint pains teratogenic
how do vitamin d analogues work topically/transdermally
○ Act via VDR to modulate gene transcription in keratinocytes, fibroblasts, langerhans cells and sebaceous glands ○ Inhibit T cell activation
what is the main side effect for topical/transdermal vitamin d analogues
skin irritation
