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Flashcards in 2 - Topical Vitamin D3 Deck (52):
1

ProVitamin D3 (7-dehydrocholesterol) is converted to PreVitamin D3 (9,10-secosterol precolecalciferol) in the epidermis by UVB light

True

2

ProVitamin D3 is 7-dehydrocholesterol

True

3

PreVitamin D3 is 9,10-secosterol precolecalciferol

True

4

Temperature-dependant Isomerisation of PreVitamin D3 (9,10 secosterol precolecalciferol) to Vitamin D3 (cholecalciferol) occurs in the epidermis

True

5

Calcitriol (1,25 dihydroxyvitamin D3) is the active hormone

True

6

Vitamin D3 (cholecalciferol) undergoes hydroxylation to 25-hydroxyvitamin D3 in the liver via CYP-450 dependant enzyme 25-hydroxylase

True

7

25-hydroxyvitamin D3 is further hydroxylated to form the active hormone 1,25-dihydroxyvitamin D3 (calcitriol) in the kidney and other tissues

True

8

Keratinocytes have all the necessary enzymes to convert ProVitamin D3 (7-dehydrocholesterol) to 1,25-dihydroxyvitamin D3 (calcitriol)

True

9

Calcitriol (1,25-dihydroxyvitamin D3) is metabolised to 1,24,25-trihydroxyvitamin D3 by 24-hydroxylase in the kidney and skin

True (1,24,25-trihydroxyvitamin D3 has very little biological activity as compared to calcitriol)

10

Topical application of calcitriol to human skin markedly enhances the activity of 24-hydroxylase to metabolise the active hormone to a less active form of 1,24,25-trihydroxyvitamin D3

True

11

Calcitriol acts mainly via the VDR (vitamin D receptor) to regulate cell growth, differentiation, immune function, calcium and phosphorus metabolism

True

12

The VDR (vitamin D receptor) protein belongs to the thyroid hormone, corticosteroid, and retinoids acid nuclear receptor gene family

True

13

Calcitriol inhibits proliferation of keratinocytes

True

14

Calcitriol modulates epidermal differentiation

True

15

Calcitriol inhibits production of interleukin 2 and interleukin 6 by T cells

True

16

Calcitriol blocks transcription of interferon gamma and granulocyte macrophage colony stimulating factor mRNA

True

17

Calcitriol inhibits cytotoxic T cell and natural killer cell activity

True

18

Vitamin D analogues have a reduced risk of hypercalcaemia but preserve other vitamin D mediated cellular effects

True

19

Calcipotriene (calcipotriol) has greater efficacy than calcitriol and tacalcitol

True

20

Calcipotriol is less likely to induce hypercalcaemia and hypercalciuria than tacalcitol

True

21

Calcipotriol is a synthetic analogue of calcitriol

True

22

Calcipotriol binds to the Vitamin D Receptor (VDR) with the same affinity as calcitriol but is less likely to cause hypercalcaemia and hypercalciuria than calcitriol

True (owing to calcipotriol's rapid local metabolism when applied topically)

23

Tacalcitol has less hypercalcaemic activity than calcitriol

True (tacalcitol differs structurally from calcitriol and similar to calcipotriol, it has less hypercalcaemic activity than calcitriol)

24

Calcipotriol applied twice daily is more effective than once daily application

True

25

Twice daily application of calcipotriol is not associated with increased irritation

True

26

Calcipotriol is well tolerated in patients with intertriginous psoriasis even though 50% experience minimal burning or slight lesional/perilesional irritation

True

27

Calcipotriol is relatively contraindicated in conditions causing hypercalcaemia

True

28

Once daily calcipotriol-betamethasone dipropionate combination therapy showed similar efficacy to twice daily calcipotriol monotherapy in the treatment of nail psoriasis

True (due to once daily dosing the calcipotriol-betamethasone dipropionate combination application may improve patient compliance)

29

Calcipotriol-betamethasone dipropionate combination therapy is more effective and has a more rapid effect than calcipotriol or betamethasone dipropionate alone

True

30

Topical tacrolimus showed superior efficacy to topical calcitriol for psoriasis on the face or intertriginous areas

True

31

Combination of a vitamin D analogue and UV therapy is better than either entity alone

True (this combination causes lesions to clear more quickly and produces greater reduction in PASI)

32

Vitamin D analogues have a phototherapy sparing effect in that fewer light treatments and lower levels of radiation are required to induce a clinical response

True

33

Application of vitamin D analogues should not be applied immediately prior to phototherapy

True (the application of vitamin D analogues prior to UV irradiation induces degradation of the vitamin D analogue and can affect transmission of UV light)

34

Irradiation with UVA can reduce the concentration of calcipotriol

True

35

Vitamin D analogues should be applied after phototherapy

True

36

Combination of calcipotriol and other immunomodulatory agents I.e. Cyclosporine, acitretin and methotrexate allows lower doses of the systemic agents to be used

True (induces clearing of psoriasis at lower doses of the systemic agents)

37

Calcipotriol has been shown to be superior to betamethasone dipropionate in reducing the number and size of prurigo nodules

True

38

Patients with morphea treated with calcipotriol under occlusion demonstrated clinically significant improvement with reduction of dyspigmentation, induration, erythema and telengiectasia.

True

39

Addition of calcipotriol to psoralen plus ultraviolet A (PUVA) therapy in vitiligo enhanced the effectiveness of PUVA therapy

True (combination therapy led to higher percentages of repigmentation than with placebo or PUVA alone + earlier repigmentation and a lower cumulative UVA dose)

40

Calcipotriol and PUVA combination therapy in patients with vitiligo led to higher percentages of repigmentation than with placebo or PUVA alone

True

41

Calcipotriol and PUVA combination therapy for vitiligo led to earlier repigmentation and a lower cumulative UVA dose

True

42

There is increased efficacy and safety in the calcipotriol-betamethasone dipropionate combination therapy in vitiligo to either treatment given alone

True (combination therapy is more superior in efficacy and safety)

43

The recommended cumulative weekly dose for calcipotriol is 100g/week

True (calcipotriol can be used with great margin of safety at a dose up to 100g/week)

44

Calcipotriol produces more irritation than calcitriol

True

45

Calcipotriol application can cause lesional and perilesional irritation which is self limiting and resolves quickly once the drug is discontinued

True

46

Adjunctive topical corticosteroids reduce the likelihood of irritation from topical calcipotriol

True

47

Topical calcitriol has not been shown to produce photosensitivity

True (contrary to topical calcipotriol, calcitriol has NOT been shown to produce photosensitivity)

48

Burning occurred in patients for whom calcipotriol was added during a course of UVB therapy

True

49

Burning did not occur in patients for whom Calcipotriol was started prior to UVB

True

50

It is recommended that UVB dosage be reduced slightly when adding a vitamin D analogue to a regimen of UVB

True (mild photosensitivity has been reported in psoriatic patients treated with a combination of calcipotriol and UVB therapy)

51

Calcipotriol is a weak contact allergen and contact irritant

True

52

Calcitriol has not been shown to produce skin irritation or contact sensitisation

True (in contrast to calcipotriol which is a weak contact allergen and irritant)