Dermatology Pharmacology and Prescription Flashcards
What % of hospital admissions are due to ADRs?
3-6% (with half of these being preventable)
Define “off labels” medications
A licensed medication that is being used for an unlicensed indication
Define “specials” medication
– Unlicensed dermatological preparations
– Long history of use, no strong evidence base but clinically effective
List some causes of prescription error
- Lack of knowledge - About patient/medication/ allergies
- Mistake writing/generating the prescription
- Poor communication
- No local or national guidelines
- Pharmacy/medicine info service
Define pharmacology
The branch of medicine concerned with the uses, effects, and modes of action of drugs.
Define pharmacokinetics
The effect of the body on the drug (ADME)
Define pharmacodynamics
The effect of the drug on the body
What are the 4 main principles underlying pharmacokinetics?
Absorption
Distribution
Metabolism
Excretion
What can cause variation in pharmacokinetics?
Individual variation in response Think about – Age of patient – Pregnancy risk – Drug interactions – Pharmacogenetics
What are some 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
What is a drug vehicle?
Vehicle: pharmacologically inert, physically and chemically stable substance that carries the active drug
What factors affect absorption?
- Concentration
- Base/vehicle
- Chemical properties of the drug
- Thickness and hydration of stratum corneum
- Temperature
- Skin site
- Occlusion
What forms can a drug vehicle be?
- Solution
- Paste
- Cream
- Spray powder
- Lotion
- Shampoo
- Gel
- Ointment
- Foam
- Paint
- Tape
What is the therapeutic effect of topical steroids?
Anti- inflammatory and immunosuppressive properties:
– Regulate pro inflammatory cytokines
– Suppress fibroblast, endothelial + leukocyte function
– Vasoconstriction
– Inhibit vascular permeability
How much is a fingertip unit, and how large is the area that can be treated by one unit?
- About 0.5 g
* Should treat area double the size of one hand
What drugs can be given in fingertip units?
Topical steroid creams - very useful in children
List some side effects of topical steroid creams
- Thinning /atrophy of the skin
- Striae - stretch marks
- Bruising
- Hirsutism - excess hair
- Telangiectasia (“spider veins”)
- Acne/rosacea/perioral dermatitis
- Glaucoma
- Systemic absorption
- Cataracts
List 3 systemic drug types used in dermatology
- Retinoids
- Traditional immunosuppressants
- Biologics (also immunosuppressive)
What are retinoids and what is their function?
Vitamin A analogues
– Normalise keratinocyte function
– Anti inflammatory and anti cancer effects
List 4 retinoid drugs and their indications
– Acne isotretinoin
– Psoriasis acitretin
– Cutaneous T cell lymphoma bexarotene
– Hand eczema alitretinoin
What retinoid drug is used for acne?
Isotretinoin
What retinoid drug is used for psoriasis?
Acitretin
What retinoid drug is used for cutaneous T cell lymphoma?
Bexarotene
What retinoid drug is used for hand eczema?
Alitretinoin
What are some contraindications and side effects of retinoids?
Teratogenic
– Careful patient selection
Side effects include
– Cheilitis (dry lips) and xerosis (dry skin)
– ↑ transaminases, ↑triglycerides
– Rarely psychiatric, eye and bone side effects
List some immunosuppressants and their indication
Treatment of inflammatory skin disorders; includes: • Oral steroids • Azathioprine • Ciclosporin • Methotrexate • Mycophenolate mofetil
What are some risks 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)
Which immunosuppressants have to be closely monitored in terms of effects on FBC?
methotrexate and azathioprine
Which immunosuppressant has to be closely monitored in terms of effects on renal function?
Cyclosporin
Which immunosuppressant has to be closely monitored in terms of effects on liver function?
Methotrexate
What does the suffix “-cept” mean?
Suffix ‘-cept’ indicates that it is a it is a receptor fusion
What does the suffix “-mab” mean?
Suffix “-mab” is used to denote monoclonal antibodies
What does the infix “-zu-“ mean?
humanised biologic
What does the infix “-ix-“ mean?
chimeric biologic
What does the infix “-u-“ mean?
fully human biologic
What does the infix “-li/l-“ mean?
immunomodulator biologic
List some current licensed biologics for plaque psoriasis in UK
– Etanercept – Infliximab – Adalimumab (Also licensed for hidradenitis suppurativa) – Ustekinumab – Secukinumab – Ixekizumab
What are some risks associated with biologics?
Risk of infection
– TB reactivation
– Serious infection
– Avoid live vaccines
Risk of malignancy
TNF inhibitors – risk of demyelination
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
