2 - Topical Vitamin D3

Question 1

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

Answer 1

True

Question 2

ProVitamin D3 is 7-dehydrocholesterol

Answer 2

True

Question 3

PreVitamin D3 is 9,10-secosterol precolecalciferol

Answer 3

True

Question 4

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

Answer 4

True

Question 5

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

Answer 5

True

Question 6

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

Answer 6

True

Question 7

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

Answer 7

True

Question 8

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

Answer 8

True

Question 9

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

Answer 9

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

Question 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

Answer 10

True

Question 11

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

Answer 11

True

Question 12

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

Answer 12

True

Question 13

Calcitriol inhibits proliferation of keratinocytes

Answer 13

True

Question 14

Calcitriol modulates epidermal differentiation

Answer 14

True

Question 15

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

Answer 15

True

Question 16

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

Answer 16

True

Question 17

Calcitriol inhibits cytotoxic T cell and natural killer cell activity

Answer 17

True

Question 18

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

Answer 18

True

Question 19

Calcipotriene (calcipotriol) has greater efficacy than calcitriol and tacalcitol

Answer 19

True

Question 20

Calcipotriol is less likely to induce hypercalcaemia and hypercalciuria than tacalcitol

Answer 20

True

Question 21

Calcipotriol is a synthetic analogue of calcitriol

Answer 21

True

Question 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

Answer 22

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

Question 23

Tacalcitol has less hypercalcaemic activity than calcitriol

Answer 23

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

Question 24

Calcipotriol applied twice daily is more effective than once daily application

Answer 24

True

Question 25

Twice daily application of calcipotriol is not associated with increased irritation

Answer 25

True

Question 26

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

Answer 26

True

Question 27

Calcipotriol is relatively contraindicated in conditions causing hypercalcaemia

Answer 27

True

Question 28

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

Answer 28

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

Question 29

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

Answer 29

True

Question 30

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

Answer 30

True

Question 31

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

Answer 31

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

Question 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

Answer 32

True

Question 33

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

Answer 33

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)

Question 34

Irradiation with UVA can reduce the concentration of calcipotriol

Answer 34

True

Question 35

Vitamin D analogues should be applied after phototherapy

Answer 35

True

Question 36

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

Answer 36

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

Question 37

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

Answer 37

True

Question 38

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

Answer 38

True

Question 39

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

Answer 39

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

Question 40

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

Answer 40

True

Question 41

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

Answer 41

True

Question 42

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

Answer 42

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

Question 43

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

Answer 43

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

Question 44

Calcipotriol produces more irritation than calcitriol

Answer 44

True

Question 45

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

Answer 45

True

Question 46

Adjunctive topical corticosteroids reduce the likelihood of irritation from topical calcipotriol

Answer 46

True

Question 47

Topical calcitriol has not been shown to produce photosensitivity

Answer 47

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

Question 48

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

Answer 48

True

Question 49

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

Answer 49

True

Question 50

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

Answer 50

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

Question 51

Calcipotriol is a weak contact allergen and contact irritant

Answer 51

True

Question 52

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

Answer 52

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