Dermatology Pharmacology and Prescribing Flashcards
are adverse drug reactions common and ar ethey preventable?
3-6% of hospital admissions are due to adverse drug reactions - Half are preventable
What is a difficulty when prescribing in dermatology?
Difficulty in dermatology with rarity of some skin conditions and lack of evidence behind treatments
how is medication licensed in the uk?
• 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
what are different names for medication wihtout a licence?
Unlicensed
‘Off label’
‘Specials’
what is unlicensed medication?
Not approved for use in the UK
What is ‘Off label’ medication?
A licensed medication that is being used for an unlicensed indication
what are ‘Specials’ medication without a licence?
unlicensed dermatological preparations
Long history of use, no strong evidence base but clinically effective
what are the 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
what can be used to help prevent prescribing errors?
Pharmacy/medicine info service
what is pharmacology?
The branch of medicine concerned with the uses, effects, and modes of action of drugs
what is the definition of Pharmacokinetics?
The effect of the body on the drug
what is the defnition of Pharmacodynamics?
The effect of the drug on the body
what different things come under and need to be thought baout in relation to 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 things need to be thought about in relation to Pharmacodynamics?
- Individual variation in response
- Think about:
- Age of patient
- Pregnancy risk
- Drug interactions
- Pharmacogenetics
Influences on adherence - in a psoriasis study, Which patients stuck to treatment plan?
Female
Married
Employed
Not paying for their prescriptions
Increasing age
what are 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
what is topical therapy?
Medication applied to the skin
what are the 2 components that make up topical therapy?
Vehicle + active drug
Vehicle: pharmacologically inert, physically and chemically stable substance that carries the active drug
what are factors that affect absorption?
- Concentration
- Base/vehicle
- Chemical properties of the drug
- Thickness and hydration of stratum corneum
- Temperature
- Skin site
- Occlusion
what are the different vehicles that may be used for topical therapy?
Solution
Cream
Lotion
Gel
Foam
Tape
Paste
Spray powder
Shampoo
Ointment
Paint
what are examples of drugs that are used tropically?
Corticosteroid
Antibiotic
Antiviral
Dithranol
Vitamin analogues
Chemotherapy
Parasiticidals
Anti-inflammatory
Coal Tar
Salicylic acid
The next generation – topical immunomodulators
what is the function of topical steroids?
• Anti-inflammatory and immunosuppressive properties
What are the anti-inflammatory and immunosuppressive properties of topical steroids?
- Regulate pro inflammatory cytokines
- Suppress fibroblast, endothelial, and leukocyte function
- Vasoconstriction
- Inhibit vascular permeability
what is the strength of topical steroids like?
Range of potencies
Mild, moderate, potent, super potent
are topical steroids safe?
When used appropriately – very safe
what do you need to do when prescribing topical steroids?
• Prescribe enough!
- See BNF guide for adults
- Can use finger-tip units
what is a finger tip unit?
- About 0.5 g
- Should treat area double the size of one hand
- Useful in young children
- Charts available for age
what are some side effects of topical steroids?
- Thinning/atrophy
- Striae
- Bruising
- Hirsutism
- Telangiectasia
- Acne/rosacea/perioral dermatitis
- Glaucoma
- Systemic absorption
- Cataracts
(picture showing typical reaction from someone who has used to much steroid)
what are Systemic Treatments in Dermatology?
- Retinoids (found use in medicine where they regulate epithelial cell growth)
- Traditional immunosuppressants
- Biologics (also immunosuppressive)
what are retinoids? and what effects do they have?
• Vitamin A analogues
- Normalise keratinocyte function (an epidermal cell which produces keratin)
- Anti inflammatory and anti cancer effects
what are the 4 different retinoids used in dermatology and what for?
- Four different molecules used orally in dermatology
- Effective in:
Acne - isotretinoin
Psoriasis - acitretin
Cutaneous T cell lymphoma - bexarotene
Hand eczema - alitretinoin
who are retinoids harmful to?
Teratogenic - Careful patient selection
A teratogen is an agent that can disturb the development of the embryo or fetus. Teratogens halt the pregnancy or produce a congenital malformation (a birth defect)
what are the side effects of retinoids?
Cheilitis (dry lips) and xerosis (dry skin)
↑ transaminases, ↑ triglycerides
Rarely psychiatric, eye, bone side effects
what are immunosuppressants used for?
Treatment of inflammatory skin disorders
Effective at suppressing T cell responses
what are different kinds of immunosuppressents?
Oral steroids
Azathioprine
Ciclosporin
Methotrexate
Mycophenolate mofetil
what is the risk of taking immunosuppressents?
Risk of malignancy and serious infection
when on immunosuppressents, regular blood test monitoring is required, in particular what?
FBC (esp in methotrexate and azathioprine)
Renal function (esp ciclosporin)
Liver function (esp methotrexate)
biologics are the next generation in treatment of inflammatory conditions
what are they?
Genetically engineered proteins derived from human genes
designed to inhibit specific components of the immune system
Very effective, but expensive
what does the suffix ‘-cept’ indicate? (in biologics)
• Suffix ‘-cept’ indicates that it is a it is a Receptor fusion
Etanercept - genetically engineered fusion protein
what does the suffix “-mab” mean?
• Suffix “-mab” is used to denote monoclonal antibodies
what are some 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
How many currently licensed biologics are there for each dermatology condition?
Psoriasis – nine
Hidradenitis suppurativa – one
Chronic spontaneous urticarial – one
Atopic eczema – one
Pemphigus – one
what are the risks of biologics?
• Risk of infection
- TB reactivation
- Serious infection
- Avoid live vaccines
- Risk of malignancy
- TNF inhibitors – risk of demyelination
how are biologics being used in melanoma?
- A revolution in treatment options for advanced melanoma - ~20% 5 year survival in stage 4 disease
- Targeted treatment:
- If BRAF 600 mutation
- Vemurafenib
- Dabrafenib
- Immunotherapies
- Ipilumumab
- Pembrolizumab
