Pharmacology (General) Flashcards
The stratum corneum
The Bricks are …
The Mortar is….
flatted dead cells (corneocytes)
multiple bilayer of lipids in plate like structure
water and lipids dont mix t/f
t
lipid r hydrophobic
Two routes of crossing stratum corneum?
transcellular
intercullalr
wHAT INFLUENCES DIFFUSION
HOW PERMEABLE
CONCENTRATION
HOW MUCH HAS TO CROSS
VEHICLE DOES NOT INFLUENCE RATE AND EXTEN OF ABSORP t/f
what factors affect?
f (permiability,concentration, solb)
vehicle dictates permeability and conc (with regards to crossing stratumn corneum)
Drug solubility in vehicle important and is dictated by vehicle
Lipophilic drug in hydrophilic base will diffuse across the stratum corneum …. and diffuse into blood stream …..
lots, lots
like attracts like, hydropgilic base will stay on stratum corneum and repel the lipophilic drug into the mortar of the skin
Lipophilic drug in lipophilic base will diffuse across the stratum corneum …. and diffuse into blood stream …..
moderately, moderately
hydrophillic drug in hydrophilic base will diffuse across the stratum corneum …. and diffuse into blood stream …..
not at all, not at all
hydrophilic drug in Lipophilic base will diffuse across the stratum corneum …. and diffuse into blood stream …..
a tiny bit, a tiny bit
When drugs are applied topically only the soluble fraction provides the driving force for absorption
t/f
t
Physical and chemical factors that can influence how readily the drug disassociates from the vehicle?
Hydratig the skin (prevents water loss)
Choose the right vehicle (ointments over some creams)
Site of application
Integrity of skin (trauma, inflammation)
Decreased partitioning results from a reduction in the barrier function of the stratum corneum
t/f
F
increase partitioning
Describe molecular mechanism of glucocorticosteroids
1) Glucocorticosteroids diffuse across lipophilic cell membrane
2) Bind to receptor GR2a and activates it
Heats shock proteins disassociate from GR2a receptor
GR”a and glucocorticosteroid translocate to nucleus and form homodimers
3) Bind to glucocorticoid receptor elements on promoter region of DNA
Results in transcription of certain genes switched. Less mediator proteins, less synthesis rate.
Subcutaneous route of administration?
Drug delivered by a needle into adipose tissue just beneath epidermis
Advantages of subcutaneous route?
Slow absorption due to less circulation in adipose tissue
Can be used to introduce a depot of drug under the skin that is slowly released into circulation
Subcut administration is used for many …. drugs, such as insulin and many …. based drugs such as steroids
protein, oil based
Skin is a good route because?
Avoids first pass metabolism
Avoids potential toxicity of drugs to organs such as liver
Simple and non sterile (topical application)
Allows for steady state plasma conc to be achieved (slow release)
Skin bad route because?
Only limited drugs diffuse across epidermis
How does TDD work?
Drug accumulated in adhesive patch and diffuse across cutaneous barrier
TDD can only be used topically t/f
F can be used to treat systemic disease
TDD is most suitable for drugs that are.. (4)
1 low molecular weight
2 moderately lipophilic
3 potent
4 brief half life
Chemical enhancers of TD interact with ….. to increase permeability mainly to drugs that can already ……
lipid matrix, cross skin reasonably well
Chemical enhancers of TDD do not have an issue with irritation/toxicity t/f
F they do
Chemical enhancers of TDD are highly effective for highly water soluble drugs or macromolecules
F
they are NOt HIGHLY effective for highly waater soluble drugs, mostl work for drugs that lipophilic
agents for chemical enhancers of TDD include
…… - this creates a ‘pore’ pathway and causes prolonged occlusion
………, such as ehthanol
………, such as sodium dodecyl sulphate
water, solvents, surfactants
Management of itch?
1) Treat CAUSE (ONDANESTRON opiate antagonist - buildup causes itch in liver problems, anti epileptics for certain neurogenic causes of itch)
2) Anti itch ttreatment
- anti histamines
- cooled emollients
- antidepressants
- phototherapy (dampens immune response)
Mild: Moderate: Potent: Very potent: (mometasone, hydrocortisone, clobetasol,modrasone)
Mild: Hydrocortisone
Moderate: Modrasone
Potent: Mometasone
Very potent: Clobetasol
Side effects of topical corticosteroids?
- Thinning of skin
- Purpura
- Stretch marks
- steroid rosacea
- fixed telangectasia
- Perioral dermatitis
- May mask infections
- Tachypulaxis: decrease in response to anti-inflammatory effects
- rebound flare disease (body stops producing own steroids)
What is an example of an antipuritic?
Menthol lotion
Capaicin - reduces neural transmission from red chilli peppers
An example of a keratolytic? Where is it used?
Used for viral warts, hyperkeratotic eczema and psoriasis, corns
SALICYLIC ACID
Dithranol works how? Used where? Disadvantages?
Slows cell replication
Stable chronic plaque psoriasis
Messy and smelly
Vitamin D analogue works how? Used where? Pros and cons?
Affects rate of cell division
Stable chronic plaque psoriasis
Can be irritant. Clean no smell, easy to apply
Coal tar works how? Used where? Disadvantages?
antiinflammatory
Stable chronic plaque psoriasis
Messy and smelly
Treatment for scalp psoriasis?
Greasy ointments to soften scale
Tar shampoo
Steroids in alcohol base or shampoo
Vitamin D analogues
Wet wrap therapy?
This is used for very dry (xerotic) skin with mosituriser, cooling and soothing. prevent scratch aply paste time consuming
Indications for topical corticosteroids?
Eczema
Psoriasis (eg flexures) Beware rebound, triggering pustular psoriasis)
Other non-infective inflammatory dermatoses e.g. lichen planus
Keloid scars (usually intralesional)
Tacrolimus and pimecrolimus are examples of?
Calicneurin inhibitors
Calcineurin inhibiter work how? When and for what? Risks and cons?
Suppress lymphocyte activation.
Second line treatment eczema
Risk infection and skin cancer?
burning sensation on application
Antiseptics indicated for? Examples?
Recurrent infections
Antibiotic resisistance
Wound irrigation
Triclosan, hydrogen peroxide
Treatment for shingles?
Treat with acyclovir 800mg 5 times daily for 7-10 days
Tramadol for 4 days
Local cooling agents
Dermatitis herpetiformis lab confirmation? What condition is associated w dermatitis herpetiformis?
IGA anti tissue transglutaminase and FBC
celiac disease
