Pharmacology in Dermatology Flashcards
Prescribing Difficulties in Dermatology
Difficulty in dermatology with rarity of some skin conditions and lack of evidence behind treatments.
3-6% of hospital admissions are due to adverse drug reactions
Half are preventable
Licensed medication
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 **
Medicine without licence
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.
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
Patient adherence
Between one third to a half of all medicines prescribed for long term conditions are not taken as recommended
Essential to take a non-judgmental approach
Not the patient’s problem
Not about taking more medication
Factors 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
** The NHS spends £100 million annually on unused medicine **
Pharmacology
The branch of medicine concerned with the uses, effects, and modes of action of drugs.
Pharmacokinetics
The effect of the body on the drug
Pharmacodynamics
The effect of the drug on the body
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
Pharmacodynamics
Individual variation in response Think about Age of patient Pregnancy risk Drug interactions Pharmacogenetics
Topical therapy
Medication applied to the skin
Vehicle + active drug
Vehicle: pharmacologically inert, physically and chemically stable substance that carries the active drug
Factors that affect topical absorption
Concentration Base/vehicle Chemical properties of the drug Thickness and hydration of stratum corneum Temperature Skin site Occlusion
Vehicle 11
Solution Paste Cream Spray powder Lotion Shampoo Gel Ointment Foam Paint Tape
Drugs used topically
Examples include:
Corticosteroid Chemotherapy Antibiotic Parasiticidals Antiviral Coal Tar Dithranol Anti-inflammatory Vitamin analogues Salicylic acid
The next generation – topical immunomodulators
Topical Steroids
Anti- inflammatory and immunosuppressive properties
Regulate pro inflammatory cytokines
Suppress fibroblast, endothelial, and leukocyte function
Vasoconstriction
Inhibit vascular permeability
Range of potencies
Used appropriately – very safe
Prescribe enough!
See BNF guide for adults
Can use finger-tip units.
Finger tip unit
About 0.5 g
Should treat area double the size of one hand
Useful in young children
Charts available for age
