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Dermatology > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

Which layer of skin is most important for drug absorption?

A

Keratin layer

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2
Q

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

A

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)

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3
Q

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

A

Vehicle (ointment, cream, gel)

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4
Q

What determines the choice of vehicle?

A

Physiochemical properties & the clinical condition

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5
Q

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

A 
Fick's Law 
Takes into account 
- partition co-efficient 
- diffusion co-efficient 
- length of diffusion pathway 
- concentration of the drug
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6
Q 
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
A
  1. lipophilic drug in hydrophilic base
  2. lipophilic drug in lipophilic base
  3. hydrophilic drug in lipophilic base
  4. hydrophilic drug in hydrophilic base
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7
Q

What can be added to a drug to enhance absorption?

A

Excipients e.g. propylene glycol

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8
Q

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

A

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

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9
Q

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

gel, paste, cream, powder, lotion, ointment

A

lotion - cream - ointment - gel - paste - powder

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10
Q

How does increased portioning arise?

A

From a reduction in the barrier function of the stratum corneum

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11
Q

Briefly outline the mechanism of action of glucocorticoids

A

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

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12
Q

What is subcutaneous administration?

A

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

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13
Q

What are the advantages of subcutaneous administration?

A

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

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14
Q

What is the disadvantage of subcutaneous administration?

A

Limited injection volume

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15
Q

What is the main advantage of giving drugs through skin?

A

Avoids first pass metabolism and absorption can be terminated rapidly

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16
Q

What drugs are suitable for transdermal delivery?

A

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

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17
Q

State the advantages of transdermal delivery

A

Steady rate of delivery & user friendly

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18
Q

State the disadvantage of transdermal delivery

A

Few drugs are suitable - GTN, estradiol, nicotine

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19
Q

Describe the purpose of chemical enhancers

A

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

20
Q

Name a chemical enhancer

A

Water - enhances pore pathway

21
Q

Name four methods of physical enhancement

A
  • 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)
22
Q

What are the advantages of topical skin therapeutics?

A

Direct application and reduced systemic effects

23
Q

What are the disadvantages of topic skin therapeutics?

A

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

24
Q

Describe creams

A

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

25
Q

Describe ointments

A

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

26
Q

Describe lotions

A

Liquid formulation of medication in water, liquid or alcohol

27
Q

Describe gels

A

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

28
Q

Describe pastes

A

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

29
Q

Describe foams

A

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

30
Q

What are emollients?

A

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

31
Q

What can be used for extremely dry skin?

A

Wet Wrap Therapy

32
Q

Name three actions of corticosteroids

A
  • vasoconstrictive
  • anti-inflammatory
  • anti-proliferating
    By acting on keratinocytes & fibroblasts
33
Q

Name a mild steroid

A

hydrocortisone

34
Q

Name a moderate steroid

A 
clobetasone butyrate (eumovate)
modrasone
35
Q

Name a potent steroid

A 
mometasone 
bethamethason valerate (betnovate)
36
Q

Name a very potent steroid

A

Clobetasol proprionate (dermovate)

37
Q

When are topical steroids used?

A

Eczema, psoriasis, non-infective dermatoses, keloid scars

38
Q

State the side effects of topical steroids

A
  • steroid rebound
  • skin atrophy
  • systemic effects (HPA axis depression)
  • spread of infection
  • rosacea
  • stretch marks
  • telangiectasia
39
Q

What are calcineurin inhibitors used for?

A

Topical treatment of atopic eczema

40
Q

Give examples of calcineurin inhibitors, how do they work?

A

Tacroliums, pimecroliums - suppress lymphocyte activation without cutaneous atrophy

41
Q

How do antiseptics work?

A

Have bacteriostatic/bacteriocidal effects

42
Q

Give examples of antiseptics

A

Savlon - chlohexidine
Sterzac - triclosan
Povidone iodine
Hydrogen peroxide

43
Q

What are topical antiseptics used for?

A

Recurrent infections
Antibiotic resistance
Wound irrigation

44
Q

Name some anitpruitic agents

A

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

45
Q

What is used to treat candida?

A

Nystatin, clotrimazole, fluclazone

46
Q

What is used to treat dermatophytes?

A

Clotrimazole, terbinafine cream

47
Q

What is used to treat pityriasis versicolor?

A

Ketoconazole

Dermatology (13 decks)

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