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Biologic
Drugs for the Treatment of Psoriasis 
For
specific drug information please click on relevant drug: -
Adalimumab
- Humira
Etanercept - Enbrel
Efalizumab - Raptiva
Infliximab - Remicade
What are biologics?
Most medications are created by combining chemicals. In contrast ‘biologic
drugs’ are made from living human or animal proteins. The medications
made from these proteins are specifically designed to act in certain ways
in the body to correct something going wrong that leads to disease.
Biologics
are not new medications- they have been in use for more than 100 years.
Vaccines and insulin are considered biologics because they are derived
from living sources. It is only recently however that biologics that are
specifically targeted toward psoriasis and psoriatic arthritis have begun
to emerge as potentially promising new treatment options.
Why
are they different?
Biologics are different from other medications for psoriasis and psoriatic
arthritis because they are designed to block both diseases early in their
development - in the immune system.
Psoriasis
and psoriatic arthritis begin in the immune system when certain immune
system cells are triggered and become overactive. These overactive cells
set off a series of events in the body, eventually causing psoriasis to
develop on the skin and arthritis symptoms to develop in the joints. Biologics
work for psoriasis and psoriatic arthritis by blocking the action of certain
immune cells that play a role in the diseases. In some cases biologics
reduce the number of these cells in the skin and blood . In other cases
they block the activation of the immune cells or block the psoriasis causing
chemicals released by them.
Almost all
treatments that work for psoriasis and psoriatic arthritis impact or target
the immune system in some way. This is true for Ultra violet treatment
and systemic medications such as methotrexate and ciclosporin The difference
is that their impact on the immune system and body is broad, including
the risk of potentially serious side effects on other organs. Biologics
are more targeted and should spare the body these broad side effects and
they have the potential to be a safer option.
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How
do they work?
Biologics are designed to treat psoriasis and psoriatic arthritis by targeting
overactive cells in the body. Some biologics target a type of immune cell
called T cells while others target the chemical messengers released by
activated T cells.
T cells normally recognise bacteria and viruses and coordinate the immune
response to eliminate these foreign invaders.
In psoriasis
certain T cells are mistakenly activated and migrate to the skin. Once
in the skin they begin to act as if they are fighting an infection or
healing a wound and this sets off a chain of events that leads to the
rapid growth of skin cells. In psoriasis skin cells grow much faster than
normal and this over production causes cells to pile up at the skins surface.
Certain biologic medications treat the psoriasis by preventing the activation
and/or migration of T cells, by reducing the number of psoriasis involved
T cells in the body, or both.
TNF -alpha
( tumour necrosis factor alpha) also helps fight infections and it communicates
messages between cells. In people with psoriasis and psoriatic arthritis
TNF alpha is produced in excess amounts by activated T cells. The messages
communicated by TNF alpha lead to the rapid growth of skin cells found
in psoriasis or to the joint pain and stiffness associated with psoriatic
arthritis.
Several biologic
medications were developed to treat rheumatoid arthritis and other diseases
by binding to TNF alpha and preventing it from communicating with cells.
It has been found that these TNF alpha agents are also effective to different
degrees in treating psoriatic arthritis and psoriasis.
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Who
can take biologics?
The biologic medications have been investigated by the National Institute
for Health and Clinical Evidence (NICE) who have issued guidelines on
when they can be prescribed. The biologic medications have been recommended
for people with severe, or very severe plaque psoriasis and severe psoriatic
arthritis who have not responded to other systemic treatments such as
PUVA, Methotrexate, Ciclosporin and Acitretin for psoriasis and at least
two disease-modifying anti-rheumatic drugs (DMARDs), given on their own
or together, for psoriatic arthritis. Or, these other treatments cause
a reaction, which means that the person shouldn’t carry on taking
them, or the person has another condition or uses another medicine that
means they should not take the other systemic treatments. With psoriatic
arthritis, the person must have arthritis with three or more tender joints
and three or more swollen joints.
In severe psoriasis and psoriatic arthritis, NICE recommends that Etanercept
(Enbrel) be offered first. Should the psoriasis or psoriatic arthritis
not show a measured response to Enbrel after 12 weeks, NICE recommends
that the treatment be stopped.
Efalizumab (Raptiva) can then be offered for treatment of severe plaque
psoriasis, or if the person has a condition or takes another medicine
that means they should not take Enbrel. Likewise, Infliximab (Remicade)
can then be offered to people with psoriatic arthritis, or if the person
has a condition or takes another medicine that means they should not take
Enbrel, also if the person has major difficulty injecting themselves.
As with Enbrel, if the person’s psoriasis or psoriatic arthritis
has not shown a measured response at 12 weeks, their treatment with Raptiva
or Remicade respectively should be stopped.
Remicade can be offered for the treatment of very severe plaque psoriasis
if the psoriasis has not responded to other systemic treatments such as
PUVA, Methotrexate or Ciclosporin. If the psoriasis has not shown a measured
response after 10 weeks then treatment should be stopped.
Key
features of the biologic drugs
• Taken by injection ( either in a surgery or at home depending
on the specific medication)
• Treatment schedule and frequency vary
• Will improve psoriasis and psoriatic arthritis for some people
but not all
• Short term side effects are generally minor although an allergic
reaction to the injection can occur
• Long term safety is still being evaluated.
• They are expensive - between £8000 and £10,000 per
annum.
• They must be taken continuously to maintain improvement.
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