3 - Photodynamic Therapy Flashcards Preview

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Flashcards in 3 - Photodynamic Therapy Deck (92):
1

Aminolevulinic acid (ALA) is a PDT photosensitiser

True

2

Methyl aminolevulinate (MAL) is a PDT photosensitiser

True

3

MAL is more lipophilic than ALA

True

4

MAL has a deeper cutaneous penetration than ALA

True (more lipophilic)

5

Penetration of the PDT photosensitiser (ALA and MAL) is inhibited by thickness of the stratum corneum

True

6

ALA and MAL enter viable cells to be transformed into porphyrins

True

7

Pretreatment with acetone scrubs can reduce incubation time of ALA and MAL by increasing penetration of these PDT photosensitisers

True

8

Pretreatment with microdermabrasian can reduce incubation time of ALA and MAL by increasing penetration of these PDT photosensitisers

True

9

Pretreatment with light chemical peels can reduce incubation time of ALA and MAL by increasing penetration of these PDT photosensitisers

True

10

Extensive photodamage more readily allows percutaneous absorption of ALA and MAL by increasing penetration of these PDT photosensitisers due to compromised skin barrier function

True

11

Skin inflammation more readily allows percutaneous absorption of ALA and MAL by increasing penetration of these PDT photosensitisers due to compromised skin barrier function

True

12

Skin abrasions more readily allows percutaneous absorption of ALA and MAL by increasing penetration of these PDT photosensitisers due to compromised skin barrier function

True

13

Exogenous ALA induces an accumulation of porphyrins

True

14

Exogenous ALA induces an accumulation of protoprophyrin IX

True

15

The mean clearance half life of fluorescence for lesions induced by ALA or MAL is 30 +/- 10 hours

True

16

The mean clearance half life of fluorescence for perilesional skin induced by ALA or MAL is 28 +/- 6 hours

True

17

The mean clearance half life of fluorescence for lesions and perilesional skin post ALA and MAL exposure is central to the importance of avoiding significant sun exposure in the 2 days following PDT treatment

True

18

Increased intracellular levels of heme inhibit the enzyme ALA synthase, providing a negative feedback on ALA synthesis

True

19

After application of ALA and MAL to human skin, porphyria accumulates mostly in sebaceous glands

True

20

After application of ALA and MAL to human skin, porphyria accumulates mostly in the epidermis

True

21

Neoplastic cells accumulate more porphyrins than normal cells

True

22

The Soret band (~410nm) is the most important excitation peak of protoprophyrin IX

True

23

The Soret band (~410nm) is included in the spectral output of the Blu-U Device that is used with ALA

True

24

A red peak of around 635nm is targeted by Aktilite that is used with MAL

True

25

Following blue or red light activation, porphyrins are excited to a higher energy triplet state and emit fluorescence

True

26

Following blue or red light activation, porphyrins are excited to a higher energy triplet state and generate reactive oxygen species

True

27

Blue or red light can have a direct PDT effect on bacteria

True (as in propionibacterium acnes which naturally accumulate porphyrins)

28

Increased collagen synthesis has been noted following ALA and MAL-PDT

True (potential mechanism that improves photoaging)

29

ALA needs to be prepared prior to application

True

30

MAL does not need to be prepared prior to application

True

31

MAL contains peanut oil

True

32

A tube of MAL needs to be discarded within 7 days of opening

True

33

ALA is available in a patch formulation in Europe

True

34

PDT is used for treatment of non-hyperkeratotic AKs on the face and scalp

True

35

ALA is in a hydroalcoholic solution

True

36

No occlusion is used with ALA

True

37

ALA uses a blue light source from the Blu-U device)

True

38

MAL is a cream formulation

True

39

MAL is more lipophilic than ALA

True

40

Occlusion is used with MAL

True

41

MAL uses a red light source

True (Aktilite light source)

42

The downtime for PDT is usually less than 1 week

True

43

ALA and MAL can be applied to lesion and surrounding skin for Field treatment of actinic keratoses

True

44

ALA depends on exposure to a 10J/cm2 blue light

True

45

MAL depends on exposure to a 37J/cm2 red light which lasts between 8-10 mins

True

46

A phototoxic reaction is significantly higher with longer exposure times to ALA and MAL

True

47

Prior to MAL application, the skin is prepped by removal of crusts or hyperkeratosis with a currette

True

48

MAL is applied under occlusion for 3 hours

True

49

2 MAL-PDT sessions may be conducted 7 days apart

True (in practice the interval is typically 2 weeks apart)

50

Evidence suggests that MAL-PDT can be used for treatment of superficial BCC

True

51

Evidence suggests that MAL-PDT is less convincing for the treatment of nodular BCC as compared to superficial BCC

True

52

ALA-PDT is not approved for treatment of superficial BCC

True (no long term studies on efficacy - MAL is the choice for superficial BCC)

53

MAL induces good clinical response for SCC in situ

True

54

MAL is preferred over ALA for treatment of SCC in situ even though both are effective

True (exact cure rate and long term recurrence rate have not been thoroughly studied in ALA as compared to MAL)

55

Both ALA and MAL are used off label for treatment of acne

True

56

Red light is preferred over blue light for treatment of acne independent of ALA or MAL application

True (red light penetrates deeper as sebaceous glands are involved in acne)

57

ALA is applied 1-3 hours prior to blue light exposure

True

58

Both ALA and MAL-PDT improve photoaging

True

59

Porphyria is contraindicated in ALA and MAL-PDT

True

60

ALA and MAL are contraindicated in persons with sensitivity to porphyrins

True

61

MAL cream may contain almond oil

True

62

PDT is contraindicated in morpheaform and pigmented BCC

True

63

ALA is pregnancy category C

True

64

MAL is pregnancy category C

True

65

ALA and MAL is contraindicated in children

True

66

MAL and ALA have no mutagenic effects

True

67

Sun exposure on the treated ALA and MAL sites should be avoided for at least 48 hours

True

68

Topical retinoids should be avoided during PDT

True (increased phototoxic reactions following ALA-PDT)

69

Burning sensation are observed during light exposure after ALA or MAL application

True

70

Pain is observed during light exposure after ALA or MAL application

True

71

Pruritus may be observed during light exposure after ALA or MAL application

True

72

Regional nerve blocks may help to alleviate the pain associated with PDT

True

73

Topical application of anaesthetics is usually not effective in alleviating the pain associated with PDT

True

74

Oedema may follow PDT treatment

True (lasts up to 1 week)

75

Erythema may follow PDT treatment

True (lasts up to 2 weeks)

76

Peeling may follow erythema after PDT treatment

True

77

Prolonged facial erythema lasting a few months after PDT is rare

True

78

The phototoxic reaction following PDT is more severe if patients expose themselves to the sun or powerful artificial lights in the first 2 days

True

79

Hyperpigmentation may occur after PDT

True (fades over time)

80

Hypopigmentation may occur after PDT

True

81

Allergic contact dermatitis may occur from MAL

True

82

Urticaria may occur from MAL

True

83

The systemic absorption of ALA is low

True

84

Concomitant use of other photosensitising drugs may increase the phototoxic reaction by PDT

True

85

Acetone may be used to scrub the skin to degrease and reduce surface keratin prior to ALA application

True

86

A margin of 5mm is used for Lesions for MAL-PDT

True

87

The skin should be cleansed with water after the incubation period of MAL or ALA, prior to light exposure

True

88

Appropriate blue or red protective eyewear should be worn by patients and staff during light exposure of PDT

True

89

Physical sunscreen agents are needed to protect against visible light photosensitivity for the 48 hours post PDT

True (chemical sunscreens do not work due to presence of porphyrins in the skin - need physical sunscreens instead)

90

Physical sunscreens may provide a certain degree of protection for the 48 hours post PDT

True (though preferably patients should not expose themselves to sunlight or intense light for 48 hours)

91

A sunscreen containing iron oxide may offer some protection against blue light sensitivity induced by ALA in the first 48 hours

True

92

Broad based sunscreens are encouraged in the weeks after PDT to prevent hyperpigmentation

True