White soft paraffin
When there are just a few plaques, very little
more than the rubbing in of whitesoft paraffin (Vaseline) once or
twice a day need be recommended. Other emollients may be tried -
in general, the thicker and greasier they are the more effective
they are. The least they will do is to improve the appearance and
decrease the scaling.
If there are one or two thickly encrusted
patches then it is sometimes useful to apply a salicylic acid preparation
for a week or two to remove the scale. Two to six percent salicylic
acid in white soft paraffin is useful for this purpose.
Tars
If further treatment is required a tar preparation can be prescribed.
Tar ointment is the simplest but not the most elegant cosmetically.
There are several quite good proprietary preparations, such as Clinitar
or Alphosyl.
For psoriasis of the groin, navel and the submammary
areas a weak tar cream (e.g. Alphosyl) can be tried although even
this is often irritating. For this type of psoriasis topical corticosteroids
may be better (see opposite).
Unfortunately some tar preparations
tend to be messy and may stain. Patients should be warned of this
and told to use only a thin smear, as well as to cover the treated
sites with cotton gauze or some other type of light dressing. Tar
can also cause redness and soreness on sun exposed areas ('tar smarts')
and may also cause an acne type of folliculitis in some patients.
Dithranol
If tars are ineffective then use can be made of the proprietary
preparations of dithranol (e.g. Dithrocream, Dithrolan, Exolan,
Psora date and Stie-Lasan). At one time dithranol treatment was
almost totally restricted to in-patients. This need no longer be
the case. Nonetheless the preparations available are not perfect
and still produce characteristic staining of the skin, clothes and
bedclothes. They also tend to irritate the skin and the patient
must be warned of this possibility. Both tar and dithranol preparations
need only be applied once daily in most patients. More frequent
applications rarely give added benefit. Tar and dithranol applications
take at least three weeks to produce improvement but it can be as
long as eight weeks before improvement is obvious.
Typical mauvish-brown staining from dithranol treatment.
Calcipotriol
Calcipotriol (Donovex) is an analogue of vitamin D that, when used
in a concentration of 50 J.lg/ g, has been found to be very effective
for plaque-type psoriasis. It may be expected to clear or considerably
improve psoriatic lesions in approximately 65 per cent of patients
in an eight to ten week period. Its only major disadvantage is a
propensity to irritate the skin - preventing its use by 20 to 25
per cent of subjects. Other vitamin D analogues are being developed
and will be available in the near future.
Corlicosteroids
There
was a vogue for the use of potent topical corticosteroids in psoriasis.
There is little doubt that they can rapidly improve the lesions
but unfortunately the disadvantages of their use in this disease
outweigh their advantages. It seems that in most psoriatic patients
the suppression of the disease that the topical corticosteroids
induce is operative only while the preparation is being used. Immediately
it is stopped the disease tends to return. What is more, it sometimes
seems to return with additional vigor. In addition, these compounds
may have unpleasant side-effects both locally and systemically as
a result of absorption.
It would be misleading to suggest that there
is absolutely no place for the use of topical corticosteroids in
psoriasis, but many dermatologists would agree that they have a
very limited role to play. Corticosteroid creams or lotions can,
however, be very useful for psoriasis of the groin, the navel and
the submammary areas. If they are used for this type of psoriasis
it is important to make sure that the condition being treated is
in fact psoriasis and not ringworm or thrush. They are also sometimes
useful in psoriasis of the scalp and flexures of the face.
Shampoos
Psoriasis of the scalp can be difficult to treat. It is best to
advise that the patient adopt a short hair style to allow frequent
shampooing. When the scalp is quite thickly encrusted it should
be shampooed on alternate days at least and preferably every day.
A regimen I often recommend is application of an ointment at night
and shampooing first thing in the morning. This leaves the scalp
free of messy ointments during the day. As far as the actual shampoos
and applications are concerned, a tar-based shampoo (e.g. Poly tar
liquid) and a tar-and-salicylic acid ointment is quite useful. If
this doesn't do the trick then a weak or moderately potent corticosteroid
cream can be applied after shampooing.
For psoriasis of the nails
Unfortunately there is no effective topical remedy for psoriasis
of the nails. When the nail involvement is not severe, all that
needs to be done is to keep the nails short. Injection of corticosteroid
suspensions around the nail beds has been tried but is painful and
not very effective. If there is severe nail involvement then this
will be a factor in persuading the specialist that systemic therapy
is indicated.
