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Anthralin
Anthralin has been widely used
in the past as an effective treatment for psoriasis
but is now prescribed less frequently because, like
tar, it is messy and stains clothing. Anthralin is able
to stop psoriatic skin cell turnover, has an anti-inflammatory
effect and is most effective on chronic plaque-type
psoriasis.
Anthralin is available in different
concentrations, and therapy usually starts at a low
potency with a gradual increase in the strength until
the desired effect is obtained. Psoriasis treatment
centers may use the Ingram Regimen, which involves applying
anthralin prior to exposing the skin to ultraviolet-B
light. The Ingram Regimen is generally used to treat
moderate to severe psoriasis.
Another method of treating psoriasis
with anthralin involves Short Contact Anthralin Therapy
(SCAT) with higher potencies of anthralin, applied to
the skin, kept on for a short period of time and then
washed off. Application time is generally increased
with subsequent applications until the psoriasis lesions
have improved.
Unfortunately, anthralin is very
messy and can discolor the skin, hair and clothes. Newer
preparations that stain less are now available. Anthralin
can also be irritating to the skin.
After application, it is advisable
to wash the hands carefully. It is also important that
patients do not expose anthralin to sensitive body areas
and other untreated areas. If anthralin gets in the
eyes, irritation can occur.
Vitamin
D Analogue—Calcipotriol
Calcipotriol is a derivative of
vitamin D that became available in Canada in 1991 and
was subsequently approved for U.S. distribution. Vitamin
D can slow the rate at which psoriatic skin cells multiply.
Calcipotriol also has anti-inflammatory properties.
This topical treatment can be found in ointment, cream
or solution form. Calcipotriol comes in one strength
(0.005%) and is available in 15,60 and 100 g tubes (cream
and ointment) and 30 mL and 60 mL scalp solutions. It
is typically applied once or twice daily to the affected
area, and improvements are usually seen within four
to eight weeks.
Its major advantage over topical
steroids is that it is a non-steroidal therapy and therefore
lacks many of the possible local side effects seen with
steroids, such as skin thinning.
Although calcipotriol is well
tolerated, it does have some drawbacks: it is slow to
take effect and may cause irritation after application,
particularly on the face and in skin folds. Another
rare side effect is an increase in the levels of calcium
in the blood stream. The risk of increased calcium levels
(hypercalcemia) is not seen if the maximum dose of 100
g of calcipotriol per week is not exceeded in adults.
Calcipotriol might need to be
used in combination with another topical therapy, phototherapy
or systemic medications in order to improve effectiveness.
In 2001, a combination of calcipotriol and betamethasone
dipropionate in the treatment of chronic plaque-type
psoriasis was investigated and proved very effective.
Because this new combination treatment includes a high-potency
topical steroid, it is generally used for shorter periods,
usually for one month. After that time, another topical
therapy can be substituted. Currently, there are plans
for clinical trials involving lower potency steroids
in combination with calcipotriol, and different forms
(lotions) which could allow treatment in the scalp.
It is important to note
that calcipotriol is inactivated by salicylic acid,
and lesions should not be pre-treated with such keratolytics.
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