Dermatology pharmacology and prescribing Flashcards
what makes a medication liscenced?
Approved for use in UK either by
MHRA – Medicines and Healthcare Products Regulatory Agency
EMA – European Medicines Agency
High standards of safety and quality
Trial evidence to show positive effect
SMC submission
Scottish Medicines Consortium
when is medication not liscenced?
Unlicensed
Not approved for use in the UK
‘Off label’
A licensed medication that is being used for an unlicensed indication
‘Specials’
unlicensed dermatological preparations
Long history of use, no strong evidence base but clinically effective.
what are causes of prescription errors?
Lack of knowledge
About the patient, the medication, allergies
Mistake writing/generating the prescription
Poor communication
No local or national guidelines
Pharmacy/medicine info service
what factors are associated with poor adherence?
Psychiatric co-morbidities
Slower acting agents
Multiple applications per day
Lack of patient education
Cosmetic acceptability of treatments
Unintentional non-adherence
what is pharmacokinetics?
The effect of the body on the drug
what is pharmacodynamics?
The effect of the drug on the body
what needs to be thought about in terms of pharmacokinetics?
Need to think about route of administration
topically where possible
If oral, optimal absorption important
Distribution – where the drug goes
Metabolism – especially in liver disease
Excretion – especially in renal disease
what needs to be thought about in terms of pharmacodynamics?
Individual variation in response
Think about
Age of patient
Pregnancy risk
Drug interactions
Pharmacogenetics
what is topical therapy?
Medication applied to the skin
Vehicle + active drug
Vehicle: pharmacologically inert, physically and chemically stable substance that carries the active drug
what factors effect topical absorption?
Concentration
Base/vehicle
Chemical properties of the drug
Thickness and hydration of stratum corneum
Temperature
Skin site
Occlusion
what are examples of drugs that are used topically?
Corticosteroid Chemotherapy
Antibiotic Parasiticidals
Antiviral Coal Tar
Dithranol Anti-inflammatory
Vitamin analogues Salicylic acid
what are topical steroids?
Anti- inflammatory and immunosuppressive properties
Regulate pro inflammatory cytokines
Suppress fibroblast, endothelial, and leukocyte function
Vasoconstriction
Inhibit vascular permeability
what do topical steroids do?
Regulate pro inflammatory cytokines
Suppress fibroblast, endothelial, and leukocyte function
Vasoconstriction
Inhibit vascular permeability
how are units of topical steroids measured for children especially?
About 0.5 g
Should treat area double the size of one hand
Useful in young children
Charts available for age
what are side effects of topical steroids?
Thinning /atrophy
Striae
Bruising
Hirsutism
Telangiectasia
Acne/rosacea/perioral dermatitis
Glaucoma
Systemic absorption
Cataracts
what are systemic treatments in dermatology?
Retinoids
Traditional immunosuppressants
Biologics (also immunosuppressive)
what are retinoids?
Vitamin A analogues
Normalise keratinocyte function
Anti inflammatory and anti cancer effects
Four different molecules used orally in dermatology
when is use of retinoids effective?
Acne isotretinoin
Psoriasis acitretin
Cutaneous T cell lymphoma bexarotene
Hand eczema alitretinoin
can retinoids be used in pregnant patients?
Careful patient selection
what are side effects of retinoids?
Cheilitis(dry lips) and xerosis (dry skin)
↑transaminases, ↑triglycerides
Rarely psychiatric, eye, bone side effects
what are immunosuppressants?
Treatment of inflammatory skin disorders
Oral steroids
Azathioprine
Ciclosporin
Methotrexate
Mycophenolate mofetil
what risks are associated with immunosuppressants?
Risk of malignancy and serious infection
Need regular blood test monitoring, in particular
FBC (esp in methotrexate and azathioprine)
Renal function (esp ciclosporin)
Liver function (esp methotrexate)
what are biologics?
The next generation in treatment of inflammatory conditions
Genetically engineered proteins derived from human genes
designed to inhibit specific components of the immune system
Very effective, but expensive
how are biologics named?
A series of infixes which immediately precede –mab:
zu humanised
ix chimeric
u fully human
li-/-l- immunomodulator
E.g.adalimumab = immunomodulator fully human monoclonal antibodies
Infliximab = immunomodulator chimeric monoclonal antibodies
