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Derm Pharm 2020 > 3 - Photodynamic Therapy > Flashcards

3 - Photodynamic Therapy Flashcards

1
Q

Aminolevulinic acid (ALA) is a PDT photosensitiser

A

True

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2
Q

Methyl aminolevulinate (MAL) is a PDT photosensitiser

A

True

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3
Q

MAL is more lipophilic than ALA

A

True

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4
Q

MAL has a deeper cutaneous penetration than ALA

A

True (more lipophilic)

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5
Q

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

A

True

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6
Q

ALA and MAL enter viable cells to be transformed into porphyrins

A

True

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7
Q

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

A

True

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8
Q

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

A

True

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9
Q

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

A

True

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10
Q

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

A

True

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11
Q

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

A

True

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12
Q

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

A

True

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13
Q

Exogenous ALA induces an accumulation of porphyrins

A

True

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14
Q

Exogenous ALA induces an accumulation of protoprophyrin IX

A

True

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15
Q

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

A

True

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16
Q

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

A

True

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17
Q

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

A

True

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18
Q

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

A

True

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19
Q

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

A

True

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20
Q

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

A

True

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21
Q

Neoplastic cells accumulate more porphyrins than normal cells

A

True

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22
Q

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

A

True

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23
Q

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

A

True

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24
Q

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

A

True

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25
Q

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

A

True

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26
Q

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

A

True

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27
Q

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

A

True (as in propionibacterium acnes which naturally accumulate porphyrins)

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28
Q

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

A

True (potential mechanism that improves photoaging)

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29
Q

ALA needs to be prepared prior to application

A

True

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30
Q

MAL does not need to be prepared prior to application

A

True

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31
Q

MAL contains peanut oil

A

True

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32
Q

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

A

True

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33
Q

ALA is available in a patch formulation in Europe

A

True

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34
Q

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

A

True

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35
Q

ALA is in a hydroalcoholic solution

A

True

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36
Q

No occlusion is used with ALA

A

True

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37
Q

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

38
Q

MAL is a cream formulation

39
Q

MAL is more lipophilic than ALA

40
Q

Occlusion is used with MAL

41
Q

MAL uses a red light source

A

True (Aktilite light source)

42
Q

The downtime for PDT is usually less than 1 week

43
Q

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

44
Q

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

45
Q

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

46
Q

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

47
Q

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

48
Q

MAL is applied under occlusion for 3 hours

49
Q

2 MAL-PDT sessions may be conducted 7 days apart

A

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

50
Q

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

51
Q

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

52
Q

ALA-PDT is not approved for treatment of superficial BCC

A

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

53
Q

MAL induces good clinical response for SCC in situ

54
Q

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

A

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

55
Q

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

56
Q

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

A

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

57
Q

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

58
Q

Both ALA and MAL-PDT improve photoaging

59
Q

Porphyria is contraindicated in ALA and MAL-PDT

60
Q

ALA and MAL are contraindicated in persons with sensitivity to porphyrins

61
Q

MAL cream may contain almond oil

62
Q

PDT is contraindicated in morpheaform and pigmented BCC

63
Q

ALA is pregnancy category C

64
Q

MAL is pregnancy category C

65
Q

ALA and MAL is contraindicated in children

66
Q

MAL and ALA have no mutagenic effects

67
Q

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

68
Q

Topical retinoids should be avoided during PDT

A

True (increased phototoxic reactions following ALA-PDT)

69
Q

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

70
Q

Pain is observed during light exposure after ALA or MAL application

71
Q

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

72
Q

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

73
Q

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

74
Q

Oedema may follow PDT treatment

A

True (lasts up to 1 week)

75
Q

Erythema may follow PDT treatment

A

True (lasts up to 2 weeks)

76
Q

Peeling may follow erythema after PDT treatment

77
Q

Prolonged facial erythema lasting a few months after PDT is rare

78
Q

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

79
Q

Hyperpigmentation may occur after PDT

A

True (fades over time)

80
Q

Hypopigmentation may occur after PDT

81
Q

Allergic contact dermatitis may occur from MAL

82
Q

Urticaria may occur from MAL

83
Q

The systemic absorption of ALA is low

84
Q

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

85
Q

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

86
Q

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

87
Q

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

88
Q

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

89
Q

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

A

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

90
Q

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

A

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

91
Q

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

92
Q

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

Derm Pharm 2020 (47 decks)

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