Skin pharmacology Flashcards

1
Q

What pharmologcial methods can we use to treat skin conditions?

A

Topical

Systemic

Drugs that induce reactions in the skin, e.g. psoralen

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2
Q

What ways can we use the skin to deliver drugs to the body?

A

Transdermal application

Topical

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3
Q

What is the difference between transdermal and topical administration?

A

Transdermal: application of drug to the skin with the intent that the drug will act elsewhere in the body

Topical: application of the drug to the damaged skin, the drug acts locally

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4
Q

What methods of transdermal administration are there?

A

Transdermal patch: a sticker

Iontopheresis: use of electric currents to get the drug through the skin

Micro-needles: the future, tiny needles that help drug bypass the skin barrier

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5
Q

How do transdermal patches work?

A

Apply to skin, the drug passes through the skin slowly providing a slow release of the drug over a long time period

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6
Q

The skin is a highly effective barrier, how does the drug get across it from a transdermal patch?

A

The drugs used need to be lipophilic

The stratum corneum (outer layer) is lipid rich, so the drug can get through it and into the body

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7
Q

What features must a drug given transdermically have?

A

Lipid soluble

High affinity

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8
Q

What are the advantages of transdermal patches?

A

This route bypasses the first-pass effect

Self-administration

Lasts over long periods of time

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9
Q

What is the first-pass effect?

A

When a drug is given orally, its concentration is greatly reduced because it is metabolised by the liver before it can act

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10
Q

What drugs are given transdermically?

A
HRT
Contraception
Nicotine replacement
Angina
Pain relief
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11
Q

What drug is used to treat angina transdermically?

A

GTN: glyceryl trinitrate

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12
Q

Name some factors that affect the delivery of the drug via a transdermal patch?

A

The skin type
How much fact there is
The placement of the patch
Body temperature

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13
Q

How does glyceryl trinitrate help treat angina?

A

Nitroglycerin converts to NO

Affects the smooth muscle
A vasodilator

More blood flow to heart, less ischaemia and pain

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14
Q

What drug is often given for pain relief via a transdermal patch?

A

Fentanyl, an opiate

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15
Q

What are the side effects of fentanyl?

A

Fever
Breathing problems
These usually resolve when you take off the patch

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16
Q

In what ways is a fentanyl transdermal patch better and worse than oral morphine?

A

Better:

  • much lower dose is required to get the same effect
  • great for chronic pain due to slow release

Worse:
- slow onset of action

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17
Q

What is iontopheresis?

A

A transdermal patch that uses electrical currents to get the drug in through the skin more efficiently

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18
Q

What are micro-needles?

A

Apart from sounding really cute!

They are tiny needles that allow the drug to pass the skin barrier and get into the body

Currently in development still

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19
Q

What forms can you get drugs in to give topically?

A

Ointment: made with grease

Pastes: powder suspended in ointment

Cream: made with water and grease

Lotion: liquid, wet

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20
Q

Which form of topical drug is best for very potent drugs that may cause damage to surrounding healthy tissue?

A

Pastes: they stay where they are put

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21
Q

What do emollients do to the skin?

A

Hydrate, soothe, reduce itching

They can help repair the damaged epithelial barrier

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22
Q

What is the benefit of having urea in an emollient?

A

Urea dissolves the intercellular matrix of the cells of the stratum corneum, promoting desquamation of scaly skin,

It helps to soften hyperkeratotic areas.

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23
Q

Name some ‘barrier cream’?

What do they do?

A

Silicones and Zinc oxide

They help create a barrier on the skin, to prevent pathogens and allergens getting in

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24
Q

When given topically, what does salicylic acid do?

What type of drug is it?

A

Facilitates breakdown of keratin to soften skin

It is a keratolytic

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25
Q

Different drugs target receptors in different regions of the body’s cells. Name some common targets?

A

Cytoplasmic receptors
Nuclear receptors
Cell membrane receptors

26
Q

What drugs target cytoplasmic receptors? (skin only)

A

Glucocorticoids

Mineralocorticoids

27
Q

How do glucocorticoids help skin disease? How do they work?

A

Vasoconstriction
Anti-inflammatory
Immunosuppressive
Anti-proliferative

They inhibit NFkB pathway
By doing this they inhibit pro-inflammatory cytokine expression
And stimulate anti-inflammatory cytokine production

28
Q

Name some pro and anti-inflammatory cytokines?

A

Pro: IL1, 2, 6, TNFa

Anti: IL-10

29
Q

Which skin diseases are glucocorticoids used in?

Which diseases are they not recommended and why?

A

Used in eczema, insect stings, etc.

Not used in acne + psoriasis due to rebound effect on withdrawal of drug

Not used in widespread infections since it’s an immunosupressive

30
Q

Adverse affects of topical corticosteroids?

A

Atrophy of skin
Glaucoma if used around eye
Infection
Acne + rosacea

31
Q

Which drugs target nuclear receptors?

A

Vitamin D analogues

Vitamin A analogues

32
Q

Name a vitamin D analogue?

A

Calcipotriol (dovonex!)

33
Q

How do vit D analogues help in skin disease?

A

They are anti-inflammatory and anti-proliferative

34
Q

Which diseases are vitamin D analogues used to treat?

A

Psoriasis, especially plaque

35
Q

Who should you not give vit D analogues to?

A

People who are known to be hypercalcaemic

An adverse effect of these drugs is hypercalcaemia, but it is rare

36
Q

Name a vitamin A analogue?

A

Isotretinoin: a systemic vitamin A analogue

There are many more

37
Q

What is retinol?

A

Vitamin A

38
Q

How do vitamin A analogues help in skin disease?

A

They inhibit cell proliferation by affecting the cell’s DNA

Prevent hyperkeratosis, and skin proliferation

39
Q

What is the problem with vitamin A analogues?

A

They are teratogenic

Drying and irritating to skin and mucous membranes

40
Q

What is calcineurin?

A

An enzyme that activates chain reactions to promote IL-2 synthesis

IL-2 is a pro-inflammatory cytokine

41
Q

How do calcineurin inhibitors help in skin disease?

A

Inhibiting calcineurin inhibits the promotion of IL-2 synthesis, reducing inflammation

42
Q

Name some calcineurin inhibitors?

A

Tacrolimus

Ciclosporin

43
Q

How does methotrexate help treat psoriasis?

A

Inhibits the metabolism of folic acid

Which inhibits proliferation, inflammation

44
Q

Problems with methotrexate?

A

Hepatotoxic
Need to supplement folic acid
Needs to be an injection once a week

45
Q

Which drug is given as an adjuvant to phototherapy? Why?

A

Psoralen

Because it further increases the damage done to nucleic acids in DNA by UVA

It enhances the damage

46
Q

How does PUVA therapy work?

A

Psoralen combined with UVA

UVA and psoralen act to damage nucleic acids in DNA

This prevents replication, reducing hyperproliferation

47
Q

Which monoclonal antibodies are used to treat psoriasis?

A

TNF-a antibodies

  • infliximab
  • adalimumab
48
Q

There are 4 types of immune reactions that can occur to drugs. Name them?

A

TYPE 1: allergic

TYPE 2: antibody mediated

TYPE 3: immune complex

TYPE 4: delayed hyper-sensitivity

49
Q

Describe and give an example of a type 1 drug reaction?

A

IgE against the drug/antigen already exists in the body

When the drug is given an immune reaction occurs straight away

Anaphylaxis

50
Q

Describe and give an example of a type 2 drug reaction?

A

Antibody dependent

Host cells take up the drug antigen (APCs)

IgG and M binds to the host cells and destroys them

Penicillin causing haemolytic anaemia (destruction of RBCs due to this mechanism)

51
Q

Describe and give an example of a type 3 drug reaction?

A

Deposition of immune complexes (drug antigen-antibody) in skin and microcirculation

Causes rashes and damage to organs

52
Q

Describe and give an example of a type 4 drug reaction?

A

T cell mediated

The T cells mount a response against the drug antigen

Eczema caused by topical anti-histamine

53
Q

What kind of reactions occur in the skin to drugs?

A

Exanthematous: eruptive skin rash, burning, itching

Urticaria: raised itchy red blotches (like nettle rash)

Angioedema: oedema of face

Fixed skin eruptions: blisters

Steven-Johnson syndrome

54
Q

What is Steven-Johnson syndrome?

A

Skin blistering, mucosal erosion
Systemic features: fever, malaise, arthralgia

Caused by a drug reaction

55
Q

Name some variants of Steven-Johnson syndrome?

A

Erythema multiforme

Toxic epidermal necrosis

56
Q

What type of drug is ciclosporin?

A

A calcineurin inhibitor

57
Q

What type of drug is methotrexate?

A

Anti-folic acid

58
Q

What type of drug is Calcipotriol?

A

Vitamin D analogue

59
Q

What type of drug is isotretinoin?

A

Vitamin A analogue

60
Q

What type of drug is tacrimolus?

A

A calcineurin inhibitor