page217
Side-effects
headache;
injection-site reactions;
less
commonly
nausea,
diarrhoea,
dyspepsia,
flushing,
fatigue, dizziness, drowsiness, paraesthesia, influenza-
like symptoms,
photosensitivity,
hypersensitivity
reactions (including hypotension,
bronchospasm, lar-
yngoedema,
rash,
pruritus,
serum sickness,
and
anaphylaxis);
Churg-Strauss syndrome (see notes
above), thrombocytopenia,
arthralgia, myalgia,
and
alopecia also reported
Dose
. By subcutaneous injection,
ADULT
and
CHILD
over 6
years, according to immunoglobulin E concentration
and body-weight,
consult product literature
Xolair
c
(Novartis) T A
Injection
, powder for reconstitution, omalizumab, net
price 150-mg vial = £256.15 (with solvent)
Excipients
include sucrose 108 mg/vial
3.4.3
Allergic emergencies
Adrenaline (epinephrine) provides physiological rever-
sal
of the immediate symptoms associated with hyper-
sensitivity reactions such as
anaphylaxis
and
angio-
edema
.
Anaphylaxis
Anaphylaxis is a severe,
life-threatening,
generalised or
systemic hypersensitivity reaction. It is characterised by
the rapid onset
of
respiratory and/or circulatory pro-
blems and is usually associated with skin and mucosal
changes;
prompt
treatment
is required.
Patients with
pre-existing
asthma,
especially
poorly
controlled
asthma,
are at
particular
risk of
life-threatening reac-
tions.
Insect stings are a recognised risk (in particular
wasp and bee stings). Latex and certain foods, including
eggs, fish, cow’s milk protein, peanuts, sesame, shellfish,
soy,
and tree nuts may also precipitate anaphylaxis.
Medicinal products particularly associated with anaphy-
laxis include blood products,
vaccines,
hyposensitising
(allergen) preparations, antibacterials, aspirin and other
NSAIDs, and neuromuscular blocking drugs. In the case
of
drugs,
anaphylaxis is more likely after
parenteral
administration;
resuscitation facilities must
always be
available for
injections
associated with special
risk.
Anaphylactic reactions
may also be associated with
additives
and
excipients
in
foods
and
medicines.
Refined arachis (peanut)
oil,
which may be present in
some medicinal products, is unlikely to cause an allergic
reaction—nevertheless it is wise to check the full
for-
mula of preparations which may contain allergenic fats
or oils.
First-line treatment
of
anaphylaxis
includes securing
the airway,
restoration of
blood pressure (laying the
patient
flat
and raising the legs,
or
in the recovery
position if
unconscious
or
nauseated and at
risk of
vomiting) and administration of
adrenaline (epinephr-
ine) injection. Adrenaline is given intramuscularly in a
dose of 500 micrograms (0.5 mL adrenaline injection 1
in 1000);
a dose of 300 micrograms (0.3 mL adrenaline
injection 1 in 1000) may be appropriate for
immediate
self-administration
. The dose is repeated if necessary at
5-minute intervals according to blood pressure,
pulse,
and respiratory function (important: possible need for
intravenous
route
using
dilute solution
,
see below).
Patients receiving beta-blockers require special
consid-
eration (see under Adrenaline,
p.
198).
High-flow oxy-
gen administration (section 3.6) and intravenous fluids
(section 9.2.2) are also of primary importance.
An anti-
histamine (e.g.
chlorphenamine,
given by slow intra-
venous injection or intramuscular injection in a dose of
10 mg, see p.
194) is a useful adjunctive treatment, given
after
adrenaline.
An intravenous
corticosteroid e.g.
hydrocortisone (as
sodium succinate)
in a dose of
200 mg (section 6.3.2) is of secondary value in the initial
management of anaphylaxis because the onset of action
is delayed for
several
hours,
but
should be given to
prevent
further
deterioration
in
severely
affected
patients.
Continuing respiratory deterioration
requires
further
treatment
with bronchodilators including inhaled or
intravenous
salbutamol
(see
p.
177),
inhaled
ipra-
tropium (see p.
180),
intravenous aminophylline (see
p.
181), or intravenous magnesium sulphate [unlicensed
indication] (see Acute Severe Asthma,
p.
171);
in addi-
tion to oxygen,
assisted respiration and possibly emer-
gency tracheotomy may be necessary.
When a patient is so ill
that
there is doubt
about
the
adequacy of the circulation,
the initial
injection of adr-
enaline may need to be given as a
dilute solution by the
intravenous
route
;
for
details of
cautions,
dose,
and
strength,
see under Intravenous Adrenaline (Epinephr-
ine),
p.
198.
Cardiopulmonary arrest
may follow an anaphylactic
reaction;
resuscitation should be started immediately
(see p.
139).
For advice on the management of medical emergencies
in dental practice,
see p.
26.
On discharge, patients should be considered for further
treatment with an oral antihistamine (section 3.4.1) and
an oral corticosteroid (section 6.3.2) for up to 3 days to
reduce the risk of
further reaction.
Patients should be
instructed to return to hospital if symptoms recur and to
contact their general practitioner for follow-up.
Patients who are suspected of
having had an anaphy-
lactic reaction should be referred to a specialist
for
specific allergy diagnosis.
Avoidance of
the allergen is
the principal
treatment;
if
appropriate,
an adrenaline
auto-injector should be given or a replacement supplied
(see Self-administration of Adrenaline).
Intramuscular adrenaline (epinephrine)
The
intramuscular route
is the
first choice route
for the
administration of
adrenaline (epinephrine) in the man-
agement of anaphylaxis.
Adrenaline is best given as an
intramuscular injection into the anterolateral
aspect of
the middle third of
the thigh;
it
has a rapid onset
of
action after
intramuscular
administration and in the
shocked patient
its absorption from the intramuscular
site is faster and more reliable than from the subcuta-
neous site (the intravenous route should be reserved for
extreme emergency when there is
doubt
about
the
adequacy of the circulation, see Intravenous Adrenaline
(Epinephrine), below).
Patients with severe allergy should be instructed in the
self-administration of adrenaline by intramuscular injec-
BNF 61
3.4.3 Allergic emergencies
197
3
Respiratory system