C H A P T E R 1 7
Immune modulators
263
■■
Immune stimulants assist the immune system to fight
specific pathogens or cancer cells; in doing so they
cause flu-like symptoms (lethargy, muscle and joint
aches and pains, anorexia, nausea).
■■
Interferons are used to treat various cancers and
warts.
■■
Interleukins stimulate cellular immunity and inhibit
tumour growth.
IMMUNE SUPPRESSANTS
Immune suppressants (Table 17.2) often are used in
conjunction with corticosteroids, which block the
inflammatory reaction and decrease initial damage to
cells. They are especially beneficial in cases of organ
transplantation and in the treatment of autoimmune
diseases. The immune suppressants include T- and
B-cell suppressors, an interleukin-receptor antagonist
and
monoclonal antibodies
—antibodies produced by a
single clone of B cells that react with specific antigens.
KEY POINTS
T-
and
B-
cell
suppressors
Several T- and B-cell immune suppressors are available
for use. Of the numerous agents available, cyclosporin
is the most commonly used immune suppressant. Addi-
tional agents include abatacept (
Orencia
), azathioprine
(
Imuran
), cyclosporin (
Sandimmun
,
Neoral
), glatiramer
(
Copaxone
), mycophenolate (
CellCept
), pimecrolimus
(
Elidel
), sirolimus (
Rapamune
) and tacrolimus (
Prograf
).
Therapeutic actions and indications
The exact mechanism of action of the T- and B-cell
suppressors is not clearly understood. It has been
shown that they block antibody production by B cells,
inhibit suppressor and helper T cells, and modify the
release of interleukins and of T-cell growth factor (see
Figure 17.1).
The T- and B-cell suppressors are indicated for the
prevention and treatment of specific transplant rejec-
tions. See Table 17.2 for usual indications of each agent.
Pharmacokinetics
Cyclosporin is well absorbed from the GI tract, reaching
peak levels in 1 to 2 hours. It is extensively metabo-
lised in the liver by the cytochrome P450 system and
is primarily excreted in the bile. The half-life of the
drug is about 19 hours for
Sandimmun
and 8.4 hours
for
Neoral.
It is available as an oral solution that can
be mixed with milk, chocolate milk or orange juice for
ease of administration. Abatacept must be given as a
30-minute infusion every 2 to 4 weeks, depending on
the person’s response. Peak levels are reached at the end
of the infusion. Abatacept has a half-life of 12 to 23 days
and usually reaches a steady state by 60 days of treat-
ment. The drug is cleared from the body by the kidneys.
Azathioprine is rapidly absorbed from the GI tract,
reaching peak levels in 1 to 2 hours. This drug is catab-
olised in the liver and red blood cells.
Little is known about the pharmacokinetics of glati-
ramer. Some of it is immediately hydrolysed on injection,
some enters the lymph system and some may actually
reach the systemic circulation.
Mycophenolate is readily absorbed and immediately
metabolised to its active metabolite. Most of the metab-
olised drug is then excreted in the urine.
Sirolimus is rapidly absorbed from the GI tract,
reaching peak levels in 1 hour. It is extensively metabo-
lised in the liver, partly by the cytochrome P450 system.
The drug is then excreted primarily in the faeces.
Tacrolimus (not available in New Zealand) is rapidly
absorbed from the GI tract, reaching peak levels in
1.5 to 3.5 hours. It is extensively metabolised in the liver
by the cytochrome P450 system and is excreted in the
urine.
■
■
Monitor for severe reactions, such as severe
hypersensitivity reactions, and
arrange to
discontinue the drug immediately if they occur
.
■
■
Arrange for supportive care and comfort measures
for flu-like symptoms (e.g. rest, environmental
control, paracetamol)
to help the person cope with
the drug effects
. Ensure that the person is well
hydrated during therapy
to prevent severe adverse
effects
.
■
■
Instruct women in the use of barrier contraceptives
to avoid pregnancy during therapy because of the
potential for adverse effects on the fetus
.
■
■
Offer support and encouragement
to deal with the
diagnosis and the drug regimen
.
■
■
Provide teaching about measures to avoid adverse
effects; warning signs of problems; and proper
administration technique.
Evaluation
■
■
Monitor response to the drug (improvement in
condition being treated).
■
■
Monitor for adverse effects (flu-like symptoms,
GI upset, CNS changes, bone marrow depression).
■
■
Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects
to watch for, specific measures to avoid adverse
effects).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
