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

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Flashcards in 3 - PUVA, NB-UVB and UVA-1 phototherapy Deck (79):
1

UVA wavelength is 320-400nm

True

2

UVB wavelength is 311nm

True

3

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

True

4

Psoralens are naturally occurring compounds acting as natural insecticides

True

5

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

True

6

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

True

7

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

True

8

Psoralens are lipophilic and poorly soluble in water

True

9

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

True

10

The water solubility of psoralens determines the bioavailability of these compounds

True

11

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

True

12

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

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)

13

High fat foods can slow down the absorption of psoralens

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)

14

Nausea is associated with high serum levels of psoralen

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

15

Psoralens exhibit first pass metabolism in the liver and intestines

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

16

Psoralens highly bind to serum albumin

True

17

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

True

18

The physical formulation of psoralen influences its absorption

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

19

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

True

20

Cytochrome P450 inducers have an effect on the metabolism of psoralens

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

21

Most of 8-MOP is excreted in the kidneys

True

22

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

True

23

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

True

24

PUVA therapy causes selective immunosuppression

True

25

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

True

26

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

True

27

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

True

28

The eczematous and plaque stages of mycosis fungoides respond to PUVA

True

29

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

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

30

Sezary syndrome is not responsive to PUVA

True

31

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

True

32

Pemphigoid is contraindicated in PUVA and NB-UVB

True

33

Pemphigus is contraindicated in PUVA and NB-UVB

True

34

Lactation is contraindicated in PUVA

True (because psoralens is probably secreted in breast milk)

35

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

True

36

Xeroderma pigmentosum is contraindicated in PUVA and NB-UVB

True

37

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

True

38

PUVA dose should be readjusted when patient is concurrently on doxycycline

True (photosensitising agent)

39

PUVA dose should be readjusted when patient is concurrently on fluoroquinolones

True (lomefloxacin and sparfloxacin are photosensitising agents)

40

The PUVA radiation dose is dependant on skin phototype

True

41

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

True

42

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

True

43

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

True

44

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

True

45

Eye protection with UVA blocking glasses is required for PUVA therapy

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

46

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

True

47

Nausea correlates with the serum level of psoralen

True (most common adverse effect)

48

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

True

49

Symptomatic erythema is the most common phototoxic reaction

True (10% of patients)

50

PUVA may cause CNS disturbances

True

51

PUVA may cause depression

True

52

PUVA may cause headaches

True

53

PUVA may cause hyperactivity

True

54

PUVA lentigines is an association of PUVA treatment

True

55

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

True (dose dependant)

56

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

True

57

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

True

58

PUVA may cause herpes simplex virus recurrences

True

59

There is no increased incidence of cataracts with PUVA

True

60

Thiazides diuretics do not cause acute phototoxic erythema with PUVA

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

61

Carbamazepine may reduce the effectiveness of PUVA

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

62

Phenytoin may reduce the effectiveness of PUVA

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

63

Other CYP 450 inducers may reduce the effectiveness of PUVA

True (enhance the metabolism of psoralen)

64

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

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

65

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

True

66

UVB is absorbed in the epidermis and papillary dermis

True

67

UVA wavelengths generally penetrate to the mid dermis

True

68

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

True

69

Bullae may appear on psoriatic plaques after NB-UVB phototherapy

True

70

Lupus erythematosus may be a consequence of NB-UVB treatment

True

71

Pemphigus may be a consequence of NB-UVB treatment

True

72

Pemphigoid may be a consequence of NB-UVB treatment

True

73

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

True

74

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

True

75

UVA-1 wavelength is 340-400nm

True

76

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

True (no clear advantage of UVA-1)

77

UVA-1 produces DNA damage in vivo and in vitro

True

78

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

True

79

Erythema from UVA-1 phototherapy is usually asymptomatic

True (usually asymptomatic and does not interfere with treatment)