page110
MANNITOL
Indications
see notes above; glaucoma (section 11.6)
Cautions
extravasation causes inflammation and
thrombophlebitis;
monitor fluid and electrolyte bal-
ance,
serum osmolality,
and pulmonary and renal
function;
assess cardiac function before and during
treatment;
interactions:
Appendix 1 (mannitol)
Contra-indications
severe cardiac failure;
severe
pulmonary oedema; intracranial bleeding (except
during craniotomy);
anuria;
severe dehydration
Renal impairment
use with caution in severe impair-
ment
Pregnancy
manufacturer advises avoid unless essen-
tial—no information available
Breast-feeding
manufacturer advises avoid unless
essential—no information available
Side-effects
less commonly
hypotension,
thrombo-
phlebitis,
fluid and electrolyte imbalance;
rarely
dry
mouth,
thirst,
nausea,
vomiting,
oedema,
raised
intracranial pressure,
arrhythmia, hypertension,
pulmonary oedema, chest pain, headache,
con-
vulsions,
dizziness,
chills,
fever,
urinary retention,
focal osmotic nephrosis,
dehydration,
cramp,
blurred
vision,
rhinitis,
skin necrosis,
and hypersensitivity
reactions (including urticaria and anaphylaxis);
very
rarely
congestive heart failure and acute renal failure
Dose
. Cerebral oedema and raised intra-ocular pressure, by
intravenous infusion over 30–60 minutes, 0.25–2 g/kg
repeated if necessary 1–2 times after 4–8 hours
Note
For mannitol 20%,
an in-line filter is recommended (15-
micron filters have been used)
Mannitol
(Baxter) A
Intravenous infusion
,
mannitol 10%,
net price 500-
mL
Viaflex
c
bag = £2.26,
500-mL
Viaflo
c
bag =
£2.15;
20%,
net price 250-mL
Viaflex
c
bag = £3.27,
250-mL
Viaflo
c
bag = £3.27, 500-mL
Viaflex
c
bag =
£3.29,
500-mL
Viaflo
c
bag = £3.12
2.2.6
Mercurial diuretics
Mercurial
diuretics are effective but
are now almost
never used because of their nephrotoxicity.
2.2.7
Carbonic anhydrase
inhibitors
The carbonic anhydrase inhibitor acetazolamide is a
weak diuretic and is little used for its diuretic effect. It is
used for
prophylaxis against
mountain sickness [unli-
censed indication] but is not a substitute for acclimati-
sation.
Acetazolamide and eye drops of dorzolamide and brin-
zolamide inhibit the formation of aqueous humour and
are used in glaucoma (section 11.6).
2.2.8
Diuretics with potassium
Many patients
on diuretics
do not
need potassium
supplements (section 9.2.1.1).
For many of
those who
do,
the amount of potassium in combined preparations
may not be enough, and for this reason their use is to be
discouraged.
Diuretics with potassium and potassium-sparing diur-
etics should not usually be given together.
Counselling
Modified-release potassium tablets
should be
swallowed whole with plenty of fluid during meals while
sitting or standing
Diumide-K Continus
c
(Teofarma) A U
Tablets
,
white/orange,
f/c,
furosemide 40 mg,
potas-
sium 8 mmol for modified release,
net price 30-tab
pack = £3.00.
Label:
25,
27, counselling,
see above
Neo-NaClex-K
c
(Goldshield) A U
Tablets
, pink/white, f/c, bendroflumethiazide 2.5 mg,
potassium 8.4 mmol for modified release,
net price
100 tab-pack = £8.99.
Label:
25, 27,
counselling,
see
above
2.3
Anti-arrhythmic drugs
2.3.1 Management of arrhythmias
2.3.2 Drugs for arrhythmias
2.3.1
Management of
arrhythmias
Management of an arrhythmia requires precise diagno-
sis of the type of arrhythmia, and electrocardiography is
essential; underlying causes such as heart failure require
appropriate treatment.
Ectopic beats
If
ectopic beats are spontaneous and
the patient
has
a normal
heart,
treatment
is
rarely
required and reassurance to the patient will
often suf-
fice.
If they are particularly troublesome,
beta-blockers
are sometimes effective and may be safer than other
suppressant drugs.
Atrial
fibrillation
All
patients with atrial
fibrillation
should be assessed for their risk of
stroke and throm-
boembolism,
and thromboprophylaxis given if
neces-
sary (see below).
Atrial
fibrillation can be managed by
either controlling the ventricular rate or by attempting
to restore and maintain sinus rhythm.
All
haemodynamically unstable patients
with acute-
onset atrial fibrillation should undergo electrical cardio-
version.
Intravenous amiodarone,
or
alternatively fle-
cainide, can be used in non-life-threatening cases when
electrical cardioversion is delayed.
If urgent ventricular
rate control
is required,
a beta-blocker,
verapamil,
or
amiodarone can be given intravenously.
In haemodynamically stable patients,
a rhythm-control
treatment strategy is preferred for patients with parox-
ysmal
atrial
fibrillation;
rate-control
is
preferred for
those with permanent
atrial
fibrillation.
For
patients
with persistent atrial
fibrillation,
the treatment strategy
should be based on criteria such as age, co-morbidities,
presence of symptoms, and the relative advantages and
disadvantages of each treatment.
Ventricular rate can be controlled with a beta-blocker
(section 2.4),
or
diltiazem [unlicensed indication],
or
verapamil.
Digoxin is usually only effective for control-
ling the ventricular
rate at
rest,
and should therefore
90
2.2.6 Mercurial diuretics
BNF 61
2
Cardiovascular system