2 - Topical Vitamin D3 Flashcards
ProVitamin D3 (7-dehydrocholesterol) is converted to PreVitamin D3 (9,10-secosterol precolecalciferol) in the epidermis by UVB light
True
ProVitamin D3 is 7-dehydrocholesterol
True
PreVitamin D3 is 9,10-secosterol precolecalciferol
True
Temperature-dependant Isomerisation of PreVitamin D3 (9,10 secosterol precolecalciferol) to Vitamin D3 (cholecalciferol) occurs in the epidermis
True
Calcitriol (1,25 dihydroxyvitamin D3) is the active hormone
True
Vitamin D3 (cholecalciferol) undergoes hydroxylation to 25-hydroxyvitamin D3 in the liver via CYP-450 dependant enzyme 25-hydroxylase
True
25-hydroxyvitamin D3 is further hydroxylated to form the active hormone 1,25-dihydroxyvitamin D3 (calcitriol) in the kidney and other tissues
True
Keratinocytes have all the necessary enzymes to convert ProVitamin D3 (7-dehydrocholesterol) to 1,25-dihydroxyvitamin D3 (calcitriol)
True
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)
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
Calcitriol acts mainly via the VDR (vitamin D receptor) to regulate cell growth, differentiation, immune function, calcium and phosphorus metabolism
True
The VDR (vitamin D receptor) protein belongs to the thyroid hormone, corticosteroid, and retinoids acid nuclear receptor gene family
True
Calcitriol inhibits proliferation of keratinocytes
True
Calcitriol modulates epidermal differentiation
True
Calcitriol inhibits production of interleukin 2 and interleukin 6 by T cells
True
Calcitriol blocks transcription of interferon gamma and granulocyte macrophage colony stimulating factor mRNA
True
Calcitriol inhibits cytotoxic T cell and natural killer cell activity
True
Vitamin D analogues have a reduced risk of hypercalcaemia but preserve other vitamin D mediated cellular effects
True
Calcipotriene (calcipotriol) has greater efficacy than calcitriol and tacalcitol
True
Calcipotriol is less likely to induce hypercalcaemia and hypercalciuria than tacalcitol
True
Calcipotriol is a synthetic analogue of calcitriol
True
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)
Tacalcitol has less hypercalcaemic activity than calcitriol
True (tacalcitol differs structurally from calcitriol and similar to calcipotriol, it has less hypercalcaemic activity than calcitriol)
Calcipotriol applied twice daily is more effective than once daily application
True
Twice daily application of calcipotriol is not associated with increased irritation
True
Calcipotriol is well tolerated in patients with intertriginous psoriasis even though 50% experience minimal burning or slight lesional/perilesional irritation
True
Calcipotriol is relatively contraindicated in conditions causing hypercalcaemia
True
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)
Calcipotriol-betamethasone dipropionate combination therapy is more effective and has a more rapid effect than calcipotriol or betamethasone dipropionate alone
True
Topical tacrolimus showed superior efficacy to topical calcitriol for psoriasis on the face or intertriginous areas
True
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)
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
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)
Irradiation with UVA can reduce the concentration of calcipotriol
True
Vitamin D analogues should be applied after phototherapy
True
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)
Calcipotriol has been shown to be superior to betamethasone dipropionate in reducing the number and size of prurigo nodules
True
Patients with morphea treated with calcipotriol under occlusion demonstrated clinically significant improvement with reduction of dyspigmentation, induration, erythema and telengiectasia.
True
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)
Calcipotriol and PUVA combination therapy in patients with vitiligo led to higher percentages of repigmentation than with placebo or PUVA alone
True
Calcipotriol and PUVA combination therapy for vitiligo led to earlier repigmentation and a lower cumulative UVA dose
True
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)
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)
Calcipotriol produces more irritation than calcitriol
True
Calcipotriol application can cause lesional and perilesional irritation which is self limiting and resolves quickly once the drug is discontinued
True
Adjunctive topical corticosteroids reduce the likelihood of irritation from topical calcipotriol
True
Topical calcitriol has not been shown to produce photosensitivity
True (contrary to topical calcipotriol, calcitriol has NOT been shown to produce photosensitivity)
Burning occurred in patients for whom calcipotriol was added during a course of UVB therapy
True
Burning did not occur in patients for whom Calcipotriol was started prior to UVB
True
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)
Calcipotriol is a weak contact allergen and contact irritant
True
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)