Pharmacology

Question 1

When is topical administration usually used?

Answer 1

Superficial skin disorders
Skin infections
Itching
Dry skin
Warts

Question 2

What are the vehicles for topical administration?

Answer 2

Lotions
Creams
Ointments
Gels
Pastes
Powders

Question 3

What is Fick’s law of diffusion?

Answer 3

Rate = permeability x concentration of drug in the vehicle

Question 4

What does permeability of a drug take into account?

Answer 4

Partition co-efficient
Diffusion co-efficient
Length of the diffusion pathway

Question 5

What is the partition co-efficient?

Answer 5

The movement of the drug from vehicle into the stratum corneum

Question 6

What type of drug and vehicle are needed to reach systemic capillaries?

Answer 6

Lipophillic (easily moves through the skin)

Lipophilic or hydrophilic vehicle

Question 7

What type of drug and vehicle are needed for superficial skin conditions and why?

Answer 7

Hydrophilic drug in lipophilic base
Only partitions (moves through skin) weakly

Question 8

What type of drug and vehicle would not penetrate the skin?

Answer 8

Hydrophilic drug and base

Question 9

What are excipients and why are they used in vehicles?

Answer 9

Substances that can enhance hydrophobic drug solubility to enhance absorption

Question 10

What is the advantage to transdermal patches?

Answer 10

Excess non-dissolved drug can be included to increase duration of effectiveness and provide a constant rate of delivery

Question 11

What can the partition co-efficient be improved by?

Answer 11

Hydration of the skin by occlusion by ointment or cling film

Inclusion of excipients

Question 12

What aspects of the nature of skin influence the absorption of topical drugs?

Answer 12

Thickness of the site of application
Hydration of the skin
Integrity of the epidermis

Question 13

What skin conditions are topical steroids used treat?

Answer 13

Atopic eczema
Psoriasis
Pruritis

Question 14

How do topical steroids work?

Answer 14

Anti-inflammatory
Immunosupressant
Vasoconstricting
Anti-proliferating for keratinocytes and fibroblasts

Question 15

What are the categories of topical steroid?

Answer 15

Mild
Moderate
Potent
Very potent

Question 16

In what vehicles are topical steroids available?

Answer 16

Lotion
Cream
Ointment

Question 17

What are the side effects of high potency steroids?

Answer 17

Steroid rebound
Skin atrophy
Systemic effects
Spread of infection due to immune suppression
Steroid rosacea
Stretch marks and small superficial dilated blood vessels (telangectasia)

Question 18

What is the mechanism of action of topical steroids?

Answer 18

Signal via nuclear receptors

Lipophilic molecules, enter by diffusion

Question 19

How does subcutaneous administration work?

Answer 19

Drug inserted into the fatty (adipose) tissue just beneath the surface of the skin
Drug reaches the systemic circulation by diffusion into either capillaries or lymphatic vessels

Question 20

What are the advantages of subcutaneous administration?

Answer 20

Absorption is slow
Preferred for many protein drugs and oil-based drugs
Can be used to introduce depot of drug that is slowly released into circulation
Simple and relatively painless

Question 21

What is the disadvantage of subcutaneous administration?

Answer 21

Injection volume limited

Question 22

What is transdermal drug delivery?

Answer 22

Drug is incorporated into an adhesive patch applied to the epidermis
Drug absorption partially controlled by a drug release membrane
Absorption occurs by diffusion across cutaneous barrier

Question 23

What are the drugs that are most suitable for transdermal drug delivery?

Answer 23

Low molecular weight
Moderately lipophilic
Potent
Short half-life

Question 24

What are the advantages of transdermal delivery?

Answer 24

Steady rate of drug delivery
Decreased dosing frequency
Avoidance of first-pass metabolism
Rapid termination if half-life too short
User-friendly, convenient and painless

Question 25

What are the disadvantages of transdermal delivery?

Answer 25

Relatively few suitable drugs Allergies Cost

Question 26

What are examples of drugs that can be given by transdermal delivery?

Answer 26

Scopolamine Nicotine GTN

Question 27

What are the advantages and disadvantages of topical skin treatments?

Answer 27

Advantages: direct application, reduced systemic effects Disadvantages: time consuming, correct dosage can be difficult, messy to use

Question 28

What are the vehicles that can be used to apply drugs?

Answer 28

``` Gels Creams Ointments Pastes Lotions Foams ```

Question 29

What is a cream?

Answer 29

Semisolid emulsification of oil in water

Question 30

What are the benefits of cream?

Answer 30

High water content so cools and moisturises Not greasy Easy to apply Cosmetically acceptable

Question 31

What is an ointment?

Answer 31

Semisolid grease/oil

Question 32

What are the advantages and disadvantages of ointments?

Answer 32

Possibility of contamination so can't share Restrict water loss But greasy so less cosmetically attractive

Question 33

What is a lotion?

Answer 33

Liquid suspension or solution of medication water, alcohol or other liquid

Question 34

What are lotions used to treat?

Answer 34

Scalp conditions and other hair bearing areas

Question 35

What are gels?

Answer 35

Thickened aqueous liquids containing high molecular wight polymers

Question 36

What are gels used to treat?

Answer 36

Scalp, hair bearing areas, face

Question 37

What are pastes?

Answer 37

Semisolids that contain finely powdered material

Question 38

What are the disadvantages of pastes?

Answer 38

Stiff, greasy, difficult to apply

Question 39

What are the benefits of pastes?

Answer 39

Protective, occlusive, hydrating Can protect surrounding skin Often used in cooling, drying soothing bandages

Question 40

What are foams?

Answer 40

Colloid with two or three phases, usually a hydrophilic liquid in continuous phase with a foaming agent

Question 41

What are the advantages of foams?

Answer 41

Increased penetration of active agents | Spreads easily over large areas of skin with no greasy/oily film

Question 42

What is the action of emollients?

Answer 42

Enhance rehydration of the epidermis

Question 43

What are emollients used for?

Answer 43

All dry or scaly conditions

Question 44

When is wet wrap therapy used?

Answer 44

For very dry skin, mostly for children

Question 45

When are calcineurin inhibitors used?

Answer 45

As alternative to steroids in eczema

Question 46

What are the types of anti-invectives?

Answer 46

Antiseptics Abtibiotics Antivirals Antifungals

Question 47

What is the action of antiseptics?

Answer 47

Bacteriostatic or bactericidal

Question 48

What are the uses of antiseptics?

Answer 48

Recurrent infections Skin cleansing Wound irrigation

Question 49

What are the skin uses of antibiotics?

Answer 49

Acne and rosacea Skin infections Infected eczema

Question 50

What are the disadvantages of using antibiotics in skin conditions?

Answer 50

Resistance Sensitisation Only use if you have to

Question 51

When are antivirals used in skin conditions?

Answer 51

Herpes simplex virus cold sores Eczema herpeticum Herpes Zoster (shingles)

Question 52

When are antifungals used in skin conditions?

Answer 52

Candida | Dermatophytes (ring worm)

Question 53

When are keratolytic agents used?

Answer 53

Viral warts Hyperkeratotic eczema and psoriasis Corns and callouses To remove keratin plaques in scalp

Question 54

What is an example of a keratolytic agent?

Answer 54

Salicylic acid ointment

Question 55

How are warts treated?

Answer 55

``` Mechanical paring plus: Salicylic acid (keratolytic) Formaldehyde Silver nitrate Cryotherapy ```

Question 56

How is psoriasis treated?

Answer 56

``` Emollients and a choice of: Coal tar Vitamin D analogue Keratolytic Topical steroid Dithranol ```

Question 57

Which treatments are used in stable chronic plaque psoriasis?

Answer 57

Coal tar Vit D analogues Dithranol

Question 58

What treatments are used in scalp psoriasis?

Answer 58

Greasy ointments to soften scale Tar shampoo Steroids in alcohol base or shampoo Vit D analogues

Question 59

What treatments are used in psoriasis in axilla?

Answer 59

Topical steroids for face, flexures, groin/genitals Consider combination antibacterial and anti fungal Calcineurin inhibitors

Question 60

What are topical treatments for superficial basal carcinomas?

Answer 60

5-fluorouracil | Imiquimod

Question 61

What are possible side effects of topical therapies?

Answer 61

Burning or irritation Contact allergic dermatitis Local toxicity Systemic toxicity