| |
Common Conditions -
Psoriasis
Psoriasis therapy is in the process of total
transformation with the addition of new
biological agents to the medication scene. With
new FDA approval, we will be prepared to offer
them to our patients, having prepared and
studied well before their release.
What causes psoriasis?
The cause of psoriasis isn’t completely known
but it is now believed to be an autoimmune
disease (a disease caused by one’s own immune
system, leading it to attack one’s own otherwise
normal tissues). Some part of the skin’s immune
system is overactive and this leads to a sped up
metabolism in the skin. Normal skin renews
itself every 60 days; psoriatic skin only takes
9. Usually old, used up skin cells are shed so
slowly we don’t notice it, but the increased
turnover time in skin effected with psoriasis
leads to the characteristic “shedding” of large
flakes on a regular basis. There is also a
genetic predisposition to it, although
inheritance of psoriasis is complex. As many as
40% of people who have psoriasis report having
no family history of the disease. This may be
due to the fact that the genetics are
complicated (more than one gene involved), there
is incomplete expressivity of the genetic trait
(not everyone who has the genetic makeup for
psoriasis actually manifests the disease) or
that the psoriasis in a family member was so
mild as to go undiagnosed (e.g. a scaly scalp
may have been mistaken for dandruff or a small
patch on one elbow was ignored).
What is psoriasis?
Psoriasis is a chronic skin condition affecting
about 6 million people in the United States.
Small or large round or oval red patches with
thick white scales characterize it. These are
sometimes itchy, occasionally hurt or bleed, or
can be asymptomatic, except for the annoyance of
shedding flakes of skin. The most common
locations are elbows, knees and scalp, but it
can occur on any part of the body. 5% of people
with psoriasis also have arthritis. The onset of
psoriasis can occur at any age including
childhood and old age, although it most commonly
appears in the teens-twenties. Sunlight tends to
make it better for reasons explained below,
whereas alcohol ingestion, lack of sunlight and
stress tend to exacerbate it.
Are there different types of psoriasis?
There are different types of psoriasis.
-
Plaque type is the
most common, with round to oval raised patches
of scaly red skin.
-
Guttate psoriasis
refers to the abrupt onset of psoriasis in very
small patches spread widely over the body. This
typically occurs after being infected with a
strep throat.
-
Hand/foot
psoriasis affects mainly hands and feet.
Fingernails and toenails can be involved in any
type of psoriasis resulting in pits, thickening
and yellowish and brown discoloration.
-
Erythrodermic
psoriasis, which means the entire body, is
covered with thin red scales.
-
Pustular psoriasis
which involves small pustules (bumps filled with
pus) scattered about on the red plaques.
Erythrodermic and pustular psoriasis are serious
in that they can be accompanied by systemic
symptoms such as fever and illness and sometimes
require hospitalization, because
the skin can’t retain enough body heat or fluids
when effected in this way.
The severity is typically calculated on the
percentage of body surface involvement. The %
body surface is estimated on the “rule of 10’s”-
each arm is 10%, each leg and each half of the
torso is 20%, each hand or foot is 1% and the
head is 6%. However, sometimes psoriasis is
disabling by virtue of its location, even though
the total body surface area is small; for
instance, if it involves the hands in someone
who requires fine manual dexterity in his/her
profession.
It is estimated that about one-fifth of all
individuals with psoriasis have more than a 20%
body surface area involvement, thus making their
psoriasis difficult to treat with topical
medications and more appropriately treated with
a total body type of therapy, whether
ultraviolet light or a systemic medication.
How can I treat psoriasis?
Treatment: topical, UV light, systemic The
treatment of psoriasis partly depends on the
location of the psoriasis and how much of the
body surface is covered. In mild psoriasis (<10%
of body surface covered) topical agents (creams,
ointments, gels and lotions) are often employed
first. These usually consist of tar
preparations, topical steroids (Clobex, Vanos,
clobetasol or betamethasone), retinoids (Tazorac)
or vitamin D derivative preparations (Dovonex).
If the body surface area is too great or the
topical agents haven’t worked, ultraviolet light
treatments or systemic agents can be employed
(either oral or injectable medications). Finally
there are systemic agents (oral medicines) which
are used for moderate to severe psoriasis, when
it is impractical to use topical agents and
light treatments have failed or are impractical.
Moderate or severe psoriasis may requires
combinations of more than one treatment.
Topical There are four categories of topical
(cream, lotion, ointments or gels applied
directly to the skin) therapy used for
psoriasis: steroids, vitamin D derivatives,
retinoids (vitamin A derivatives), and tar
based.
The most common topical treatment of psoriasis
is a topical steroid. These have
anti-inflammatory properties and decrease the
redness and scaling relatively quickly. Their
main drawback is that psoriasis skin often
develops a resistance to them- that is, they
work at first but stop working after a while
(called tachyphylaxis). Also, if you stop using
them suddenly, psoriasis can flare up to a
degree that is worse than its original condition
(called rebound flare). The topical steroids are
best used in conjunction with one of the newer
topical medicines for the treatment of
psoriasis, calcipotriene and tazarotene (see
below).
Another important topical therapy is the vitamin
D derivative, calcipotriene (Dovonex). The
advantages to this therapy is that it has few,
if any, long term side effects and does not
“lose its potency” over time. The disadvantage
is that it works slowly, and as monotherapy
(only using this and no other treatment), it
isn’t too effective. However, using Dovonex
along with a potent topical steroid seems to
increase the effectiveness of both.
A third important topical therapy is the
retinoid tazarotene (Tazorac). This does a good
job with thick plaques of psoriasis. Its main
side effect is irritation so it is important to
avoid getting it on the normal skin that
surrounds the patch of psoriasis. Like Dovonex,
it works best when paired with a topical steroid
(applied at a different time of day) in order to
decrease the irritation.
Tar preparations are often effective but they
are smelly and messy. A tar-like substance, LCD
can sometimes be effective. A pharmacist can
combine these with a topical steroid
(compounded) as well.
Ultraviolet treatments Typically you would
receive ultraviolet treatments in a
dermatologist’s office standing in a box that
looks like a phone booth. These need to be
administered by trained personnel in a
dermatologist’s office as care must be taken to
gradually increase the exposure time or else a
sunburn reaction can ensue which can be severe.
In addition, these treatments typically need to
be given 2-3 times per week over a period of 2-3
months to obtain clearance in a case of
moderate-severe psoriasis. Although
inconvenient, these are highly effective
treatments for psoriasis and have been approved
by the FDA since the 1970’s. The main drawback
besides the inconvenience is that there appears
to be an increased risk of skin cancer over a
long period of time with the treatments,
particularly PUVA.
Systemic There are three main oral systemic
medicines used for the treatment of psoriasis:
acitretin (Soriatane), methotrexate and
cyclosporine.
Acitretin (Soriatane) is a retinoid, that is, a
member of a group of hormone molecules that have
many different effects on tissues. In the case
of psoriasis, it tends to modulate the tissue
metabolism, thereby decreasing the rapidity with
which psoriatic skin is made and helping to
normalize it. It is taken once or twice a day,
depending on the dosage, which is usually
25-50mg per day. This drug cannot be taken by
women of childbearing. It is relatively safe but
only moderately effective.
Methotrexate is an anticancer drug that works on
psoriasis by decreasing metabolism in overactive
cells. Given in much lower dosages than that
used for cancer, it has a 40-year track record
that has proven it to be effective, fairly well
tolerated and relatively inexpensive as a
treatment for psoriasis. It is taken orally on
1-2 days out of the week, so it is convenient.
Its main drawback is that it can cause severe
liver damage that can’t reliably be ascertained
by blood tests. This means that intermittent
liver biopsies are necessary to ensure safety.
It can also cause anemia (especially in the
initial stages of treatment), increased
susceptibility to infection (immunosuppression),
mouth or stomach ulcers and hair loss.
Cyclosporine is an immunosuppressive agent used
principally in preventing the immune system of
organ transplant patients from rejecting their
transplanted organs. The discovery that it could
treat psoriasis led to the idea that psoriasis
was an autoimmune disease. It also is taken
orally, usually in dosages ranging from 2.5-5
mg/kg (150-400 mg/day for average size adults).
It is highly effective and probably works faster
than any other anti-psoriasis medication
available, so it is particularly suitable for
people with very severe forms of psoriasis who
need rapid improvement (e.g. those with pustular
or erythrodermic psoriasis). Occasionally it is
used to get severe psoriasis under control
quickly and then to switch to another,
potentially less toxic therapy. Long-term,
low-dose therapy has also been advocated. The
main problem with cyclosporine therapy is that
is can cause hypertension (high blood pressure)
and kidney damage. Most experts don’t recommend
continuing this agent for more than one year at
a time.
Biologic
Medications in Psoriasis
The adverse
effects of systemic drugs and the frequent
visits required for phototherapy have stimulated
scientists to search for safer and more
convenient ways to treat moderate to severe
psoriasis. The search has led to the development
of “biologic” medications, made from live
materials. Four biologics—Amevive, Raptiva,
Remicade, Humira and Enbrel—are cleared by the
FDA for the treatment of moderate to severe
psoriasis.
Unlike systemic drugs and phototherapy,
biologics are “designer” drugs that attack
specific molecular targets in the immune system.
Keep in mind, however, that some of the
biologics are new, and their long-term adverse
effects are not known. The effects of biologics
on pregnant women and fetuses are not known.
To understand how these drugs work, it is
necessary to understand how the immune system
works in psoriasis.
The immune system protects against disease by
attacking foreign substances that enter the
body. The immune system has many types of cells,
such as T cells, which must be activated before
they can function. In psoriasis, “memory” T
cells are overactivated and this leads to the
appearance of psoriatic lesions on the skin.
Also, the immune system has chemical messengers,
such as tumor necrosis factor-alpha (TNF-alpha),
which stimulate certain cells to cause
inflammation. People with psoriasis have too
much TNF-alpha in their skin and people with
psoriatic arthritis have too much TNF-alpha in
their joints. The excessive TNF-alpha causes
inflammation, which damages tissues and joints.
TNF-alpha also leads to unwanted activation of T
cells and the development of psoriasis.
Both Amevive (generic alefacept) and Raptiva
(generic efalizumab) work by blocking the
activation of T cells and the migration of these
activated cells to the skin. The symptoms of
many people with psoriasis improve when they
take these drugs. Amevive is injected weekly as
an intramuscular injection (into the buttock or
the arm). Raptiva is self-injected under the
skin once per week. Both require some monitoring
via blood work.
Enbrel (generic etanercept), Remicade (generic
infliximab), and Humira (generic adalimumab)
work by reducing the amount of TNF-alpha in the
skin and joints. This interferes with the
inflammatory process and the development of
psoriatic arthritis and psoriasis. Both Enbrel
and Humira are self-injected, once or twice per
week or every other week respectively. Remicade
is an intravenous infusion which must be
administered in the office of a doctor
experienced with infusions.
Since these drugs affects the immune system,
people with a high risk of cancer or frequent
infections should not take the drug. Also,
people taking TNF inhibitors need to be
pre-screened for tuburculosis. Women who are
pregnant and persons with a history of
neurologic disease or heart disease should use
these drugs with caution. This is a small and
incomplete list of side effects. Before
beginning a medication such as this you would
need to consult thoroughly with your doctor.
Is Psoriasis
Curable?
Psoriasis is a chronic disease. Chronic means it
is long-term, i.e., lifelong as it is not
curable. It has been demonstrated that having
psoriasis significantly impacts the quality of
life for those who suffer from it . The personal
dissatisfaction associated with being afflicted
with it is expressed by the phrase “the
heartbreak of psoriasis”. In addition, it can
sometimes be difficult to truly get psoriasis
under control, even with adequate therapy. There
may be some gender differences as well, as it
appears that women may suffer more when
afflicted, partly because more aggressive
therapies are withheld due to their danger to a
potential unborn fetus. Psoriasis severity tends
to wax and wane naturally with time. It usually
gets worse in the winter, presumable because
ultraviolet light helps. It appears to also be
negatively affected by cigarette smoking,
alcohol consumption, stress and skin trauma
(called Koebnerization- areas frequently rubbed
or damaged can sometimes lead to plaques of
psoriasis). It is best to find a compassionate
dermatologist who will take the time to include
you in the treatment decision making process.
Keeping psoriasis at bay requires patience and
persistence but usually is within reach if you
have realistic expectations and expert help.
How can I find out more?
American Academy of Dermatology (AAD) 930 N.
Meachum Road Schaumburg, IL 60173 888-462-DERM
www.aad.org
National Psoriasis Foundation 6600 SW 92nd,
Suite 300 Portland, OR 97223-7915 800-723-9166
www.psoriasis.org
Where did this information come from?
Ortonne JP. Recent developments in the
understanding of the pathogenesis of psoriasis.
Br J Dermatol 1999 Apr;140 Suppl 54:1-7.
Bagel J. Establishing a practical and effective
psoriasis treatment center. Dermatol Clin 2000
Apr; 18 (2) : 349-57,xi.
Koo J. Systemic sequential therapy of psoriasis:
a new paradigm for improved therapeutic results.
J Am Acad Dermatol 1999 Sep;41(3 Pt 2):S25-8.
Shupack J, Abel E, Bauer E, Brown M, et al.
Cyclosporine as maintenance therapy in patients
with severe psoriasis. J Am Acad Dermatol 1997
Mar;36 (3 Pt. 1):423-32.
Rapp SR, Feldman SR Exum ML, Fleischer AB, et
al. Psoriasis causes as much disability as other
major medical diseases. J Am Acad Dermatol 1999
Sep;41 (3 Pt 1):401-7.
Al-Suwaiden SN, Feldman SR. Clearance is not a
realistic expectation of psoriasis treatment. J
Am Acad Dermatol 2000 May;42 (5 Pt.1) :796-802.
Hotard RS, Feldman SR, Fleischer AB.
Sex-specific differences in the treatment of
severe psoriasis. J Am Acad Dermatol 2000
Apr;42(4):620-623.
Higgins E. Alcohol, smoking and psoriasis. Clin
Exp Dermatol 2000 Mar;25(2) :107-10.
Zachariae R, Oster H, Bjerring P, Kragballe K.
Effects of psychological intervention on
psoriasis: A preliminary report. J Am Acad
Dermatol 1996;34:1008-15.
|
|
 |
