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Flashcards in Pharmacology Deck (52):
1

What dictates the choice of vehicle

Physio-chemical properties of the drug - how hydrophobic/Phillic it is
The condition of the skin

2

What are topical drugs used to treat

Superficial skin disorders - eczema etc
Skin infections
Itching
Dry skin
Warts

3

What factors of absorption are dependent on the vehicle

The concentration of drug in the vehicle
The partition coefficient

4

What are excipients

Substances added to the ointment etc that enhance solubilty and absorption
Pharmacologically inert in itself

5

What factors improve the partitioning of a drug

Hydration of the skin by occlusion - ointment or cling film
Stops water loss
Inclusion of excipients

6

How does the nature of the skin influence the topical drug chosen

Site of application - thickness of stratum corneum
Hydration of the skin
Intergrity of the epidermis

7

What are the 4 categories of steroid in the UK

Mild
Moderate
Potent
Very potent - can only be prescribed by the dermatologist

8

How do you choose a topical steroid

Depends on the severity of disease and the anatomical site

9

What are some long term effects of high potency steroids

Steroid rebound - down regulation of receptor
Skin atrophy
Systemic effects
Spread of infection
Rosacea
Stretch marks

10

Describe the subcutaneous route of administration

Needle is inserted just beneath the surface of the skin
Drug reaches systemic circulation by diffusion into capillaries or lymphatic system

11

What are the advantages of the subcutaneous route

Slow absorption
Useful for protein drugs (insulin) and oil-based drugs
Can be used to create a depot of drug that is slowly released into system
Simple and painless

12

What are the disadvantages of the subcutaneous route

Injection is volume limited

13

why is the skin a good route for drug administration

Application is simple and non sterile (for topical drugs)
Allows for steady-state plasma conc to be achieved over a long period
Avoids first pass metabolism
Drug absorption can be terminated

14

What is a disadvantage of the skin as an administration route

Intact skin is a water tight barrier so only some drugs can cross the epidermis

15

What are the advantages of topical treatment

Direct application
Reduces systemic effects

16

What are the disadvantages of topical treatment

Time consuming
Correct dosage can be difficult
Messy - issue with greasy preparations

17

What are the advantages of creams

Cooling and moisturing
Non-greasy
Easy to apply
Cosmetically acceptable

18

What are ointments useful for

Occlusive - retains moisture
Good for thickened plaques in psoriasis

19

What are lotions used for

To treat the scalp and other hair bearing areas

20

What are gels used to treat

Scalp
Hair bearing areas
Face

21

Describe pastes

Semisolid
Often contain fine powders such as ZnO
They are protective, occlusive and hydrating
Used for cooling, bandages and around ulcers

22

Describe foams and their use

2 or 3 phases - usually hydrophilic liquid in continuous phase with foam agent in gaseous phase
Gives increased penetrance of active agents
Can spread easily over large areas of skin
Non-greasy or oily

23

What are keratolytics used for

Used for treating thickened skin

24

Describe the use of emollients

Help rehydration of the epidermis - used for dry skin
Need to apply frequently an liberally
Cosmetically acceptable
Can be used as a soap substitute
Fire risk if contain paraffin

25

How do you apply emollients

Apply after bathing
Apply in direction of hair growth
Use clean spatula to remove from tub - prevents contamination

26

What are topical steroids commonly used for

Mainly eczema
Psoriasis
Other inflammatory dermatoses
Keloid scars

27

What are the side effects of topical steroids

Thinning of the skin
Purpura - dark purple marks on skin
Stretch marks
Rosacea
Fixed telangectasia
Perioral dermatitis
May worsen or mask infection
Systemic absorption
Tachyphylaxis
Rebound flare

28

What are calcineurin inhibitors

Non-steroid anti-inflammatory - e.g. Tacrolimus
Suppress lymphocyte activation
Use for atopic eczema
Less side effects than steroids
May cause burning sensation

29

What are the clinical uses of antiseptics

Recurrent infections
Antibiotic resistance
Wound irrigation
One example is potassium permanganate bath

30

What skin conditions are antivirals used for

Herpes simplex (cold sore) - topical
Eczema herpeticum - oral
Herpes zoster - oral

31

Name some topical anti-fungals

Clotrimazole
Nystatin
Ketoconazole

32

Name some fungal skin conditions

Candida - thrush
Dermatophytes - ringworm

33

What conditions might you use keratolytics for

Viral warts
Hyperkeratotic eczema and psoriasis
Corns and callouses
Removing keratin plaques from scalp

34

How would you treat a wart

Mechanical pairing - take off
Keratinolytics
Formaldehyde - soak for whole foot
Silver nitrate - localised
Cryotherapy - localised

35

What is the most common adverse drug reaction

Mainly cutaneous - show up with skin symptoms
around 30% are this

36

What types of reaction can drugs cause

Immunologically mediated reactions - all types
Not dose dependant

Non-immunological
Can be dose-dependent

37

what are the typical presentations of cutaneous drug eruption

exanthematous, maculopapular rash - 75-95% of the time
Urticarial - 5-10%
very rarely pustular etc
itch is very common
usually self-limiting
mucous membranes usually spared

38

what are the risk factors for drug eruptions

Age - very young and elderly
Gender - more in females
Genetics - predisposition
Concomitant disease - infection
Immune status - previous sensitivity
Chemistry of the drug
Route of administration
Dose
Half-life

39

how do drug reactions usually resolve

Often resolve when the drug treatment is stopped

40

how soon after taking the drugs does an eruption usually occur

onset is usually 4-21 after first taking the drug

41

what are some signs of a serious drug reaction

involvement of mucous membrane
Facial redness and swelling
Fever
Pain
Blisters, necrosis
SOB, wheezing

42

How does an urticarial drug reaction occur

usually an immediate IgE reaction (type I)after 2nd drug exposure
Can be a direct release of inflammatory mediators on first exposure

43

describe the appearance of an urticarial rash

Dermal oedema - raised wheal
Blanches if pressure is applied
Can come and go

44

Which drugs can cause a bullous or pustular reaction

Glucocorticoids
Androgens
Antibiotics
CCB
Antimalarial

45

which drugs are associated with fixed drug eruptions

Tetracycline, doxycycline
Paracetamol
NSAIDS
Carbamazepine

46

Describe the presentation of a fixed drug eruptions

Well demarcated plaques
Red and painful
in the same place - can reoccur
Often appear on hands, genitals, lips
usually mild

47

Name some severe cutaneous drug reactions

SJS
TEN - shedding of whole body superficial layer
DRESS - huge number of circulating eosinophils

48

describe a phototoxic drug reaction

non-immunological reaction caused by the drug and light
Makes skin more sensitive
Can occur in a sunburn like reaction

49

How could a phototoxic reaction present

Immediate prickling with delayed erythema & pigmentation
Exaggerated sunburn
Exposed telangiectasia
Increased skin fragility

50

what drugs are associated with phototoxicity

antibiotics
thiazides
NSAIDs
immunosuppressants
Amiodarone

51

What investigations can be used for drug reactions

Clear history
Phototesting for phototoxic reactions
Patch and photo patch test
Skin prick tests for specific drugs

52

how do you manage a cutaneous drug reaction

discontinue the drug
use alternative
antihistamine may help with some symptoms