Practice Flashcards
What are the five types of dermatological treatment?
1) surface treatment (insect repellent, sunscreen, topical anti microbial/fungal)
2) stratum corneum (solar keratosis, emollient therapy)
3) skin appendages (acne, depilatory, antiperspirant)
4) viable epidermis/dermis (anti-inflammatory, anaesthetic, antihistamine)
5) transdermal (HRT, opioid, Parkinson’s)
Examples of internal topical preparations?
Mucosal membranes, rectal, vaginal Bonjela Nystatin Clotrimazole Anusol
Advantages of topical delivery?
No first pass metabolism Controlled release More selective to target site Less side effects Easy to use Good compliance Avoid fluctuation in drug levels Efficacy with lower daily doses Easy to terminate drug action
Disadvantages of topical delivery?
Allergic reactions to active and excipients
Larger drug particles may not penetrate the skin
Only for drugs where smaller plasma concentrations are required
Enzymatic breakdown of some drugs in the skin
How do transdermal penetration enhancers act?
1) disruption of highly ordered structure of stratum corneum lipid
2) interaction with intercellular protein
3) improved partition of the drug, co-enhancer or solvent into the strain corneum
Examples of transdermal penetration enhancers?
Propylene glycol
N-methyl pyrrolidone (NMP)
Dimethyl sulphoxide (DMSO)
Laurocapram (azone)
Types of solid topical dosage forms?
Powder
Aerosol
Plaster
Types of liquid topical dosage forms?
Lotion Liniment Solution Emulsion Suspension Aerosol
Types of semi-solid topical dosage forms?
Ointment Cream Paste Gel Jelly Suppository
Ointment features?
Usually less than 20% water More than 50% hydrocarbons Greasier than other preparations Soften/melt at body temperature Translucent
Advantages of ointments?
Less skin sensitivities due to less preservatives
Good for moderate to severe dry skin
Good for night time application
Less regular applications needed
Disadvantages of ointments?
Some people don’t like the greasy feeling so can cause non-adherence
Can ‘grease’ clothes and bedding
Features of creams?
Semisolid that possesses a relatively soft, spreadable consistency
More fluid than ointments
Formulated as either water in oil or oil in water emulsions
White appearance due to scattered light from dispersed oil globules
Less greasy
Advantages of creams?
Less greasy so increased adherence
Can be used in weeping eczema
Disadvantages of creams?
More applications required
Features of lotions?
Light preparations with high water content
Oil in water emulsion
Advantages of lotions?
Spread easily
Quickly absorbed
Can use on hair areas
Can be used to deliver antibiotics, antifungals, corticosteroids etc
Disadvantages of lotions?
Poor moisturising properties
Must be shaken
Features of gels?
Semisolid systems
Consist of dispersion of small inorganic particles or large organic molecules in an aqueous suspension
Also use a gelling agent such as carbomer to thicken the colloidal dispersion
Non-Newtonian flow characteristics
Very high water content but are water insoluble
Can contain drug substances, cosolvents, anti microbial preservatives, stabilisers
Drug release rate depends of physical structure of the gel
What are emollients?
Smooth and soften skin by restoring the skin barrier
Semi-solids that contain no water (oil or grease based)
Can contain exfoliations (salicylic acid), antipruritics (lauromacrogols), lipids such as ceremides and cholesterol and antiseptics
How do emollients moisturise the skin?
Increase the amount of water in the stratum corneum in two ways:
Occlusion by trapping moisture into the skin it is best achieved by greasy emollients such as petrolatum products
Active movement of water from the dermis with low molecular weight molecules called humectants (urea, glycerine)
What are parabens?
Hydroxybenzoates Popular preservative found in creams Broad spectrum of anti microbial activity Colourless, odourless Stable Unexpensive But allergies in 1.2% of patients
What is lanolin?
Yellow, waxy substance secreted from sebaceous glands of sheep to waterproof their wool
Rarely cause reactions (hypoallergenic)
Counselling required for paraffin?
Flammable
What is sodium Lauryl Sulfate?
Surfactant and detergent
Partly water soluble and partly oil soluble this allows the water and oil to become mixed
Used in emollients for its thickening and emulsifying properties
Can be drying and may cause irritation
Advice when giving out an emollient?
Wash and dry hands and affected area
Maybe use a spatula to reduce microbial contamination or give a pump dispenser
Apply as frequently as possible and especially after bathing
Avoid bubble baths
Use as a soap substitute- either apply when wet or dry then wash off
Apply in the direction of the growing body hair
What is the recommended amount of emollient to use per week?
500-1000g per week
Half for a child
Cautions with bath oils?
Elderly and young children due to bath becoming slippery
What are adverse drug reactions?
An unwanted or harmful reaction that occurs after administration of a drug and is suspected or known to be to due to the drug
What percentage of hospital admissions are due to ADRs?
6-7%
ADRs occur in what percent of hospital inpatients?
10-20%
Implications of ADRs?
adverse effect on patients quality of life
Can cause patients to lose trust
Increased cost of patient care
Lengthen hospital stays
May mimic disease, causing unnecessary investigations
What does type A ADRs stand for?
augmented
What are type A ADRs?
Predictable Does related Morbidity high Mortality low Usually stops when the drug is withdrawn
Examples of type A ADRs?
Bleeding from warfarin
Antimuscarinic side effects from TCAs
Antimuscarinic ADRs mneumonic?
SLUMBAG Salivation, secretions, sweating (lack of) Lacrimation (lack of) Urinary retention Miosis Bradycardia, bronchoconstriction, bowel movement Abdominal cramps, anorexia GI upset
What do type B ADRs stand for?
bizarre
What are type B ADRs?
unpredictable
Rare
Often severe
Examples of type B ADRs?
anaphylaxis from antibiotics
Agranulocytosis from clozapine, carbimazole and carbamazepine
What do type C ADRs stand for?
Continuous
