pharmacology in dermatology Flashcards
what is pharmacokinetics and what affects it?
Pharmacokinetics= the effect of the body on a drug
Need to think of:
- Route of administration
- Distribution
- Metabolism – important in liver disease
- Excretion- important in renal disease
what is pharmacodynamics and what affects it
Pharmacodinamics= the effect of the drug on the body
Need to think of:
- Age of patient
- Pregnancy risk
- Drug interaction
- Pharmacogenetics
What affects individual adherence to drugs
Lack of adherence related to:
- Psychological factors
- Co-morbitidities
- Multiple applications a day
- Un-intentional
- Cosmetic complications
- Lack of education
What is administered during topical application of a drug
Active drug + vehicle
Vehicle= inactive substance which carries the active drug
What affects absorption?
- temperature
- concentration
- Vehicle
- Thickness and hydration of stratum corneum
- skin site
- occlusion
Examples of topical drugs
- Corticosteroids
- Antibiotics/ antiviral
- Chemotherapy
- Vitamin analogue
- Anti-inflammatory
- Coal tar
- Salicyclic acid
- Parasiticidals
- Topical immunomodulators- NEX GENERATION
How do topical steroids work?
Have anti-inflammatory and immunosuppressive qualities:
- Reduce the effect of pro-inflammatory cytokines
- suppress fibroblast, endothelial and leukocyte action
- vasoconstriction
- reduce vascular permeability
Side effects of topical steroids
- Atrophy
- Thinning
- Bruising
- Hirtuism
- Telangiectasia: thinning of blood vessels
- Acne/ rosacea
- Glaucoma
- Catarracts
Dosage of topical steroids
- In children: finger tip unit- should be about 0.5 grams
- BNF
Examples of systemic treatments
- Retinoids
- Traditional immunosuppressants
- Biologics (also immunosuppressive)
what are retinoids? and what do they do?
-Vitamin A analogues so:
• Normalise keratinocyte activity
• Anti-inflammatory and anti-cancer effects
which are the 4 retinoids used in dermatology?
Acne=isotretinoin
Psoriasis=acitretin
Cutaneous T cell lymphoma= bexarotene
Hand eczema=alitretinoin
contraindications for retinoids
- Teratogenic: damage to foetus
- Chelitis- dry lips
- Xerosis- dry skin
- Increases transaminases – increases protein synthesis
- Increases TAG
- rare psychiatric, eye, bone disease
which are the common immunosuppressants used in dermatology?
- Oral steroids
- Azathioprine
- Ciclosporin
- Methotrexate
- Mycophenolate mofetil
what are the contraindications for topical steroids
- Risk of infection and malignancy
- Need regular FBC FOR methotrexate and azathioprine
- Need regular LFT for methotrexate
- Need regular KFT for ciclosporin
