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
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