Pharmacology and Prescribing Flashcards
When is medicine used without license?
- Unlicensed - not approved for UK use but no alternative
- Off label - licensed meds for unlicensed indication
- Specials - clinically effective but no evidence in clinical trials
What are causes of prescription error?
- Lack of knowledge
- Mistake writing/genrating the prescription
- Poor communication
- No local or national guidelines
What are the two actions of pharmacology?
- Pharmacokinetics - the effect of the body on the drug
* Pharmacodynamics - the effect of the drug on the body
What needs to be considered with pharmacokinetics?
• Route of administration - topic where possible, but it oral, optimal absorption important
- Distribution - where the drug goes
- Metabolism - esp. in liver disease
- Excretion - esp. in renal disease
Why is topical administration advantageous?
Prevents systemic side effects
What needs to be considered with the pharmacodynamics of drugs?
• Individual variation in response
- Age of patient
- Pregnancy risk
- Drug interactions
- Pharmacogenetics
Name 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
Describe topical administration
- Medication applied to the skin
* Vehicle + active drug
Describe vehicles used in topical therapy
Pharmacologically inert, physically and chemically stable substance that carries the active drug
Name seven factors that affect absorption
- Concentration
- Base/vehicle
- Chemical properties of the drug
- Thickness and hydration of stratum corneum
- Temperature
- Skin site
- Occlusion
Name different types of vehicles
- Solution
- Cream
- Lotion
- Gel
- Shampoo
Give example of different drugs used topically
- Corticosteroid
- Antibiotic
- Chemo
- Coal tar
- Antiviral
What are the properties of topical steroids?
Anti-inflammatory and immunosuppressive properties
What are the actions of topical steroids?
- Regulate pro-inflammatory cytokines
- Suppress fibroblast, endothelial, and leukocyte function
- Vasoconstriction
- Inhibit vascular permeability
What measurement is used for topical steroids?
Finger tip unit
What are the features of the finger tip unit?
- About 0.5g
- Should treat area double the size of one hand
- Useful in young children
What are possible side effects of topical steroids
- Thinning /atrophy
- Striae
- Bruising
- Hirsutism
- Telangiectasia
- Acne/rosacea/perioral dermatitis
- Glaucoma
- Systemic absorption
- Cataracts
Name three systemic treatment in dermatology
- Retinoids
- Traditional immunosuppressants
- Biologics (also immunosuppressive)
What are retinoids?
Vitamin A analogues
• Normalise keratinocyte function
• Anti-inflammatory and anti-cancer effects
What are retinoids used to treat?
- Acne
- Psoriasis
- Cutaneous T cell lymphoma
- Hand eczema
What are the side effects of retinoids?
• Teratogenic
- Cheilitis (dry lips) and xerosis (dry skin)
- ↑transaminases, ↑triglycerides
What are immunosuppressants used to treat?
Inflammatory skin disorders
Give examples of immunosuppressants
- Oral steroids
- Azathioprine
- Ciclosporin
- Methotrexate
- Mycophenolate mofetil
What are possible side effects of immunosuppressants?
• Risk of malignancy and serious infection
Need regular blood test monitoring
• FBC
• Renal function
• Liver function
