Psoriasis Flashcards
What drugs can trigger psoriasis?
- Antimalarials
- Lithium
- B blockers
- Indomethacin
- Mepacrine
- ACE inhibitors
- Alcohol
- Topical drugs
- Overuse and sudden withdrawal of some oral corticosteroids
What is Kobners phenomenon?
- Traumatised skin resulting in a psoriatic event at the site of injury
- Cytokines released —> activate T cells
- T cells —> more cytokines, keratinocytes and inflammation
What is plaque psoriasis?
Start as small papules that then grow and unite to form a plaque
What does plaque psoriasis look like?
Classic silvery white scaly appearance
What are the major biological abnormalities of plaque psoriasis?
- Hyperproliferation of the epidermis
- Abnormal differentiation of keratinocytes
- Infiltration of the dermis and epidermis with activated T lymphocytes and neutrophils
- Stimulation of the cutaneous vasculature
What does guttate psoriasis like?
Initially start of as pink papules that become scaly, arises rapidly and responds well to treatment
When does guttate psoriasis usually occur?
After a streptococcal throat infection - possibly superantigen stimulation of the IS
What is erythrodermic psoriasis?
A severe variant that is widespread with massive protein loss, problems maintaining core body temperature and excessive fluid losses - requires aggressive treatment in hospital
What are the complications of erythrodermic psoriasis?
Pustulosis, arthropathy, staphylococcal skin infection and growth retardation
What is pustular psoriasis?
A severe form that causes superficial pustulation of the lesions often on the palms and soles
May be widespread - associated with fever and malaise, fluid and electrolyte disturbances and infection
High relapse rate - can be fatal - hospitalised
What are the main changes to nails in nail psoriasis?
- Pitting
- Oncholysis - selecting nail from nail bed
- Accumulation of subungual debris
- Colour changes
More often finger than toe nails
What is psoriatic arthritis?
In the peripheral interphalangael joints - RF not elevated - difficult to distinguish from rheumatoid arthritis
Associated with cutaneous changes - nail and scalp
What is inverse/flexural psoriasis?
Smooth inflamed lesions mostly in creases or folds - minimal or absent scaling
Perinanal skin in children and beneath breast in women
What are emollients?
Bath oils, soap substitutes and skin creams that moisturise, lubricate and soothe dry flaky skin by forming an occlusive film
To moisturise - apply liberally all over body tid
Psoriatic plaque - pretreatment
Contact dermatitis and foliculitis - ADR’s
Where is dithranol from?
Brazilian tree - Andira araroba
What does dithranol do?
- Slows cell proliferation
- Decrease inflammation
Very effective with no systemic S/E
How do you use dithranol?
- 0.05 - 0.1% starting concentration applied each night at bedtime
- Rinse off each morning - coat skin with emollient
- Increase dose after a few days
- Little increase efficacy after 5%
What are the problems with dithranol?
- Staining
- Inflammation and irritation of non psoriatic skin
- Short treatment
- 0.1% for 5-20 mins
- 1% over 5 mins - Not as effective as calcipotriol in clearing lesions
What is coal tar?
White soft or yellow soft paraffin base available in lotions, gels or shampoos
5% most effective
What are the problems with coal tar?
- Smelly, messy and stains clothing
- Irritation - can cause contact dermatitis
- Phototoxic response
- Don’t apply over a large area - use on well separated small lesions
How are corticosteroids applied?
Applied directly to lesion - goal is to increase time of remission
May make a lesion disappear but may return after discontinuation - taper strength
What do you use for plaque psoriasis?
High potency topical steroid bd until control
What are the S/E’s of corticosteroids?
- Skin atrophy - thinning of skin after 3-14 days
- Increase in fine hair growth
- Hypopigmentation
- Allergic contact dermatitis
- Systemic absorption - adrenal suppression
What is an example of a vitamin D analogue?
Calcipotriol
- 50 micrograms/gram ointment
- 50 micrograms/gram scalp lotion
Max weekly cumulative dose = 5mg ie. 100g or 100ml - use once or twice a day
- notice effect week 2
- max effect - weeks 6 to 8
- flare up if used intermittently
What are the adverse reactions of calcipotriol?
- Skin irritation - don’t use on face or flexural areas
- Peripheral ring of scales around treated lesions
- Rare - hypercalcameia
How do retinoids work?
Tazarotene
- Topically active retinoid
- Normalise keratinocyte differentiation
- Anti-proliferative and anti-inflammatory effects
- Moderately effective
- Limited by skin irritation and increased
photosensitivity - Adequate contraception required in women of child bearing age
How does phototherapy work?
- Phototherapy = UVB radiation
- Photo chemotherapy = light plus drugs
- PUVA therapy (psoralen and UVA)
- Take 2 hours before therapy
- Peak effect - 48 to 72 hours post therapy
- Shield eyes and skin from sun for 6 hours
What drugs are used for systemic therapy?
- Retinoids
- Cyclosporin
- Methotrexate
- Tacrolimus
- Psoralens
- Biologic therapy agents
What are the indications for systemic therapy?
- Failure of adequate topical trials
- Repeated hospital admission
- > 10% of body affected
- Extensive chronic plaque psoriasis in elderly or infirim
- Widespread pustular or erythrodermic psoriasis
What are retinoids used for systemic therapy?
- They are vitamin A derivatives
- Eg. Acitretin
- Most effective for pustular and erythrodermic psoriasis
- Limit to severe forms
- Initial dose —> maintenance dose
- Teratogenic
- Avoid in severe liver and kidney disease
What is systemic methotrexate used for?
- Used in patients unresponsive to topical therapy
- Can be used in severe pustular or erythroderma, arthritis and plaque involving more than 20%
- Folic acid antagonist
- Given weekly - caution
- Monitor blood, liver and kidney function
What is systemic ciclosporin used for?
- Resistant disease
- Immunosuppressant
- Use lowest possible dose
- Monitor BP and kidney function
- Never exceed 5mg/kg/day
- 90% remission in 7-10 weeks
- Relapse 2-4 months post treatment
- Tacrolimus - similar to ciclosporin
How do biological therapy agents work?
- Block T cell activation
- Inhibit T cell proliferation
- Inhibit T cell destruction
- Block effector cytokines
What biological agents are used to treat psoriasis?
- Etanercept - 12 weeks
- Infliximab - 10 weeks
- Adalimumab - 16 weeks
- Ustekinumab - 16 weeks
Consider changing to an alt biological drug in adults if the psoriasis doesn’t respond adequately to a first biological drug ( see above for time for change)
What are the risks with biologic agents?
- Risk of immunosuppressive not known
- Increased risk of infection and reactivation of TB
- S/E’s include influenza like symptoms, leucocytosis, arthralgia, exacerbation of psoriasis or development of variant forms
- 1/3 of patients respond rapidly others slowly or not at all
- Control not cure
How should topical corticosteroids be used?
Sparingly and gradually withdrawn
