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Derm Pharm 2020 > 3 - PUVA, NB-UVB and UVA-1 phototherapy > Flashcards

3 - PUVA, NB-UVB and UVA-1 phototherapy Flashcards

1
Q

UVA wavelength is 320-400nm

A

True

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2
Q

UVB wavelength is 311nm

A

True

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3
Q

Psoralen plus ultraviolet A (PUVA) photochemotherapy is the photochemical interaction between a psoralen medication and UVA radiation

A

True

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4
Q

Psoralens are naturally occurring compounds acting as natural insecticides

A

True

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5
Q

Human contact with plants containing psoralens and subsequent exposure to sunlight results in phytophotodermatitis

A

True

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6
Q

Phytophotodermatitis represents an acute phototoxic reaction in the skin manifested as erythema, blistering and pigmentation

A

True

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7
Q

The presence of psoralen in the skin before and after exposure can be harmful through unintentional exposure to sunlight resulting in undesirable phototoxicity

A

True

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8
Q

Psoralens are lipophilic and poorly soluble in water

A

True

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9
Q

There are 2 types of psoralens available, namely 8-MOP (methoxsalen) and 5-MOP (bergapten) where 8-MOP is more water soluble than 5-MOP

A

True

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10
Q

The water solubility of psoralens determines the bioavailability of these compounds

A

True

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11
Q

8-MOP (Methoxsalen) is available as 2 formulations of dissolved psoralen (Oxsoralen Ultra) and micronised crystals of 8-MOP

A

True

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12
Q

Dissolved psoralen (Oxsoralen Ultra) is rapidly and more completely absorbed as compared to the 8-MOP micronised crystals

A

True (accounts for dissolved psoralen being dosed at 0.4mg/kg and taken 1 hour prior to UVA and micronised crystals 8-MOP being dosed at 0.6mg/kg and 2 hours prior to UVA)

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13
Q

High fat foods can slow down the absorption of psoralens

A

True (psoralens is ideally taken under fasting conditions although food intake can be used to alleviate the nausea associated with high serum level of the drug)

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14
Q

Nausea is associated with high serum levels of psoralen

A

True (food intake with the drug can alleviate this adverse effect)

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15
Q

Psoralens exhibit first pass metabolism in the liver and intestines

A

True (therefore doses <20mg may not be clinically effective)

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16
Q

Psoralens highly bind to serum albumin

A

True

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17
Q

8-MOP (Methoxsalen) is more photoactive than 5-MOP (Bergapten)

A

True

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18
Q

The physical formulation of psoralen influences its absorption

A

True (8-MOP dissolved psoralen more readily absorbed than 8-MOP micronised crystals)

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19
Q

Methoxsalen (8-MOP) is completely metabolised in the liver through the CYP 450 system

A

True

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20
Q

Cytochrome P450 inducers have an effect on the metabolism of psoralens

A

True (cytochrome P450 inducers enhance and accelerate the metabolism of 8-MOP therefore reducing the biological effect of PUVA)

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21
Q

Most of 8-MOP is excreted in the kidneys

A

True

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22
Q

The peak of the absorption spectrum for psoralen molecules to be activated to the excited singlet state is in the region of 320-330nm

A

True

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23
Q

PUVA therapy suppresses DNA synthesis through the formation of monoadducts and cross links in the DNA

A

True

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24
Q

PUVA therapy causes selective immunosuppression

A

True

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25
Q

NB-UVB phototherapy is almost as effective as PUVA for psoriasis not involving the palms and soles

A

True

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26
Q

NB-UVB has replaced PUVA as the treatment of choice for vitiligo as both treatments have comparable efficacy but NB-UVB is simpler

A

True

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27
Q

Vitiligo on the face and torso are more responsive to phototherapy than on the limbs

A

True

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28
Q

The eczematous and plaque stages of mycosis fungoides respond to PUVA

A

True

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29
Q

The tumour stage of mycosis fungoides does not usually respond to PUVA

A

True (PUVA is usually not effective in the tumour phase of the disease)

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30
Q

Sezary syndrome is not responsive to PUVA

A

True

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31
Q

Patients with various photodermatoses can be desensitised by prophylactic exposure to a brief course of PUVA

A

True

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32
Q

Pemphigoid is contraindicated in PUVA and NB-UVB

33
Q

Pemphigus is contraindicated in PUVA and NB-UVB

34
Q

Lactation is contraindicated in PUVA

A

True (because psoralens is probably secreted in breast milk)

35
Q

Lupus erythematosus with photosensitivity is contraindicated in PUVA and NB-UVB

36
Q

Xeroderma pigmentosum is contraindicated in PUVA and NB-UVB

37
Q

A 25% reduction in PUVA dose should be considered in patients taking photosensitising agents

38
Q

PUVA dose should be readjusted when patient is concurrently on doxycycline

A

True (photosensitising agent)

39
Q

PUVA dose should be readjusted when patient is concurrently on fluoroquinolones

A

True (lomefloxacin and sparfloxacin are photosensitising agents)

40
Q

The PUVA radiation dose is dependant on skin phototype

41
Q

If widespread erythema is present post PUVA, treatment should be stopped until the erythema clears

42
Q

When >95% of the psoriasis area has cleared post PUVA, the patient is stepped down to a maintenance schedule of PUVA

43
Q

If a significant (>5%) amount of psoriasis begins to return then the frequency of PUVA can be increased or stepped up to a clearance schedule

44
Q

Areas shielded from PUVA therapy should be concurrently managed with topical corticosteroid therapy

45
Q

Eye protection with UVA blocking glasses is required for PUVA therapy

A

True (required from time of psoralen ingestion until sunset that day when the patient is exposed to sunlight)

46
Q

A sunscreen with at least SPF 15 ideally includes avobenzone as an ingredient is advised for photoprotection from psoralen phototoxic reaction

47
Q

Nausea correlates with the serum level of psoralen

A

True (most common adverse effect)

48
Q

The PUVA itch (pruritus) and subacute phototoxicity are indications for stopping treatment until they clear

49
Q

Symptomatic erythema is the most common phototoxic reaction

A

True (10% of patients)

50
Q

PUVA may cause CNS disturbances

51
Q

PUVA may cause depression

52
Q

PUVA may cause headaches

53
Q

PUVA may cause hyperactivity

54
Q

PUVA lentigines is an association of PUVA treatment

55
Q

NMSC incidence is markedly increased in patients who receive high cumulative UVA exposure

A

True (dose dependant)

56
Q

The SCC is PUVA patients are not biologically more aggressive than actinically induced SCCs in immunocompetent patients

57
Q

There is an increased risk of SCC on male genitalia with PUVA treatment

58
Q

PUVA may cause herpes simplex virus recurrences

59
Q

There is no increased incidence of cataracts with PUVA

60
Q

Thiazides diuretics do not cause acute phototoxic erythema with PUVA

A

True (though a potentially photoactive agent, thiazides diuretics do not cause phototoxicity with PUVA)

61
Q

Carbamazepine may reduce the effectiveness of PUVA

A

True (carbamazepine is a CYP 450 enzyme inducer and enhances the metabolism of psoralen)

62
Q

Phenytoin may reduce the effectiveness of PUVA

A

True (phenytoin is a CYP 450 enzyme inducer and enhances the metabolism of psoralen)

63
Q

Other CYP 450 inducers may reduce the effectiveness of PUVA

A

True (enhance the metabolism of psoralen)

64
Q

Skin cancer is the most important adverse effect of long term PUVA treatment

A

True (need for long term skin checks even after cessation of PUVA)

65
Q

The peak of the action spectrum for phototherapy of psoriasis is in the 320-340nm spectrum

66
Q

UVB is absorbed in the epidermis and papillary dermis

67
Q

UVA wavelengths generally penetrate to the mid dermis

68
Q

Topical emollients are advised before NB-UVB to make lesions more transparent

69
Q

Bullae may appear on psoriatic plaques after NB-UVB phototherapy

70
Q

Lupus erythematosus may be a consequence of NB-UVB treatment

71
Q

Pemphigus may be a consequence of NB-UVB treatment

72
Q

Pemphigoid may be a consequence of NB-UVB treatment

73
Q

Recurrent herpes labialis may be an adverse effect of NB-UVB treatment

74
Q

Polymorphous light eruption can be an adverse effect of NB-UVB treatment

75
Q

UVA-1 wavelength is 340-400nm

76
Q

UVA-1 treatment is equivalent to NB-UVB and UVA treatment

A

True (no clear advantage of UVA-1)

77
Q

UVA-1 produces DNA damage in vivo and in vitro

78
Q

Erythema is the main short term effect of UVA-1 phototherapy

79
Q

Erythema from UVA-1 phototherapy is usually asymptomatic

A

True (usually asymptomatic and does not interfere with treatment)

Derm Pharm 2020 (47 decks)

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