Pharmacology

Question 1

Which layer of skin is most important for drug absorption?

Answer 1

Keratin layer

Question 2

Describe the ‘brick and mortar’ structure of the keratin layer

Answer 2

Brick - corneocytes contain aggregated keratin embedding in filaggrin
Mortar - hydrophobic intercellular lipids that hold the corneocytes together (act as a reservoir for lipid soluble drugs)

Question 3

What is the name of the substance a drug is carried in?

Answer 3

Vehicle (ointment, cream, gel)

Question 4

What determines the choice of vehicle?

Answer 4

Physiochemical properties & the clinical condition

Question 5

Which law is rate of absorption described by? What does it take into account?

Answer 5

Fick's Law 
Takes into account 
- partition co-efficient 
- diffusion co-efficient 
- length of diffusion pathway 
- concentration of the drug

Question 6

Place the following in order of best absorbed to least absorbed; 
lipophilic drug in lipophilic base 
hydrophilic drug in hydrophilic base 
lipophilic drug in hydrophilic base 
hydrophilic drug in lipophilic base

Answer 6

1. lipophilic drug in hydrophilic base
2. lipophilic drug in lipophilic base
3. hydrophilic drug in lipophilic base
4. hydrophilic drug in hydrophilic base

Question 7

What can be added to a drug to enhance absorption?

Answer 7

Excipients e.g. propylene glycol

Question 8

What is used in transdermal patches to increase duration of effectiveness?

Answer 8

Excess non-dissolved drug helps to provide a constant rate of delivery

Question 9

In terms of water content list the following most to least;

gel, paste, cream, powder, lotion, ointment

Answer 9

lotion - cream - ointment - gel - paste - powder

Question 10

How does increased portioning arise?

Answer 10

From a reduction in the barrier function of the stratum corneum

Question 11

Briefly outline the mechanism of action of glucocorticoids

Answer 11

Lipophilic molecules diffuse across the membrane and combine with GRalpha to produce shock proteins - the activated receipt which moves to the nucleus binds to DNA to switch on/off transcription

Question 12

What is subcutaneous administration?

Answer 12

Insertion of a needle into adipose to allow a drug to reach the systemic circulation by diffusion into capillaries and lymphatics

Question 13

What are the advantages of subcutaneous administration?

Answer 13

Slow absorption, suitable for oil based drugs, can introduce a depot of drug (slow release)

Question 14

What is the disadvantage of subcutaneous administration?

Answer 14

Limited injection volume

Question 15

What is the main advantage of giving drugs through skin?

Answer 15

Avoids first pass metabolism and absorption can be terminated rapidly

Question 16

What drugs are suitable for transdermal delivery?

Answer 16

low molecular weight, moderately lipophilic, potent, short half life

Question 17

State the advantages of transdermal delivery

Answer 17

Steady rate of delivery & user friendly

Question 18

State the disadvantage of transdermal delivery

Answer 18

Few drugs are suitable - GTN, estradiol, nicotine

Question 19

Describe the purpose of chemical enhancers

Answer 19

Used to increase permeability particularly for drugs that already cross the skin reasonably well

Question 20

Name a chemical enhancer

Answer 20

Water - enhances pore pathway

Question 21

Name four methods of physical enhancement

Answer 21

• iontophoresis (low voltage drives low weight molecules through skin)
• electroporation (high voltage leads to pore formation)
• sonophoresis (ultrasound increases permeability)
• microneedles (punch holes into skin)

Question 22

What are the advantages of topical skin therapeutics?

Answer 22

Direct application and reduced systemic effects

Question 23

What are the disadvantages of topic skin therapeutics?

Answer 23

Time consuming, difficult to get the correct dose & can be messy to use

Question 24

Describe creams

Answer 24

Semisolid emulsions of oil in water that contain an emulsifier and preservative act to cool and moisturise due to high water content

Question 25

Describe ointments

Answer 25

Semisolid grease/oil, restricts water loss - less cosmetically attractive

Question 26

Describe lotions

Answer 26

Liquid formulation of medication in water, liquid or alcohol

Question 27

Describe gels

Answer 27

Thickened aqueous lotion - semisolid containing high molecular weight medication - used for hairy areas

Question 28

Describe pastes

Answer 28

Finely powdered material, stiff and greasy used to cool, dry and sooth bandages

Question 29

Describe foams

Answer 29

Colloid usually hydrophilic liquid with foaming agent dispersed in gaseous phase. Easy to spread over large areas of skin and increased penetration of active agents

Question 30

What are emollients?

Answer 30

Moisturisers used to rehydrate the epidermis to be applied after bathing in direction of hair growth

Question 31

What can be used for extremely dry skin?

Answer 31

Wet Wrap Therapy

Question 32

Name three actions of corticosteroids

Answer 32

• vasoconstrictive
• anti-inflammatory
• anti-proliferating
  By acting on keratinocytes & fibroblasts

Question 33

Name a mild steroid

Answer 33

hydrocortisone

Question 34

Name a moderate steroid

Answer 34

clobetasone butyrate (eumovate)
modrasone

Question 35

Name a potent steroid

Answer 35

mometasone 
bethamethason valerate (betnovate)

Question 36

Name a very potent steroid

Answer 36

Clobetasol proprionate (dermovate)

Question 37

When are topical steroids used?

Answer 37

Eczema, psoriasis, non-infective dermatoses, keloid scars

Question 38

State the side effects of topical steroids

Answer 38

• steroid rebound
• skin atrophy
• systemic effects (HPA axis depression)
• spread of infection
• rosacea
• stretch marks
• telangiectasia

Question 39

What are calcineurin inhibitors used for?

Answer 39

Topical treatment of atopic eczema

Question 40

Give examples of calcineurin inhibitors, how do they work?

Answer 40

Tacroliums, pimecroliums - suppress lymphocyte activation without cutaneous atrophy

Question 41

How do antiseptics work?

Answer 41

Have bacteriostatic/bacteriocidal effects

Question 42

Give examples of antiseptics

Answer 42

Savlon - chlohexidine
Sterzac - triclosan
Povidone iodine
Hydrogen peroxide

Question 43

What are topical antiseptics used for?

Answer 43

Recurrent infections
Antibiotic resistance
Wound irrigation

Question 44

Name some anitpruitic agents

Answer 44

menthol (calamine)
capsaicin (reduces neurotransmission)
camphor/phenol
Crotamiton (treats residual itch post scabies)

Question 45

What is used to treat candida?

Answer 45

Nystatin, clotrimazole, fluclazone

Question 46

What is used to treat dermatophytes?

Answer 46

Clotrimazole, terbinafine cream

Question 47

What is used to treat pityriasis versicolor?

Answer 47

Ketoconazole