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Minimising harm in patients with co-
morbidities
The drug chosen to treat a particular condition should
have minimal detrimental effects on the patient’s other
diseases
and minimise the patient’s
susceptibility to
adverse effects.
To achieve this,
the
Cautions
,
Contra-
indications
, and
Side-effects
of the relevant drug should
be reviewed,
and can usually be found in the drug
monograph.
However,
if
a class of
drugs (e.g.
tetracy-
clines,
p.
346)
share the same cautions,
contra-indica-
tions,
and side-effects,
these are amalgamated in the
prescribing notes while those unique to a particular drug
in that class are included in its individual
drug mono-
graph.
Occasionally,
the cautions,
contra-indications,
and side-effects may be included within a preparation
record if
they are specific to that preparation or if
the
preparation is not accompanied by a monograph.
The information under Cautions can be used to assess
the risks
of
using a drug in a patient
who has
co-
morbidities that
are also included in the Cautions for
that
drug—if
a safer alternative cannot
be found,
the
drug may be prescribed while monitoring the patient for
adverse-effects
or
deterioration in the co-morbidity.
Contra-indications are far
more restrictive than Cau-
tions and mean that
the drug should be avoided in a
patient with a condition that is contra-indicated.
The impact
that
potential
side-effects may have on a
patient’s quality of
life should also be assessed.
For
instance,
in a patient
who has
difficulty sleeping,
it
may be preferable to avoid a drug that frequently causes
insomnia.
The prescribing notes in the BNF may high-
light important safety concerns and differences between
drugs in their ability to cause certain side-effects.
Prescribing for patients with hepatic or
renal impairment
Drug selection should aim to minimise the potential for
drug accumulation, adverse drug reactions, and exacer-
bation of
pre-existing hepatic or renal
disease.
If
it
is
necessary to prescribe drugs whose effect is altered by
hepatic or renal
disease,
appropriate drug dose adjust-
ments should be made,
and patients should be moni-
tored adequately. The general principles for prescribing
are outlined under
Prescribing in Hepatic Impairment
(p.
17)
and
Prescribing in Renal
Impairment
(p.
17).
Information about
drugs
that
should be avoided or
used with caution in hepatic disease or
renal
impair-
ment can be found in drug monographs under
Hepatic
Impairment
and
Renal
Impairment
(e.g.
fluconazole,
p.
374).
However,
if a class of drugs (e.g.
tetracyclines,
p.
346)
share the same recommendations for
use in
hepatic disease or
renal
impairment,
this
advice is
presented
in
the
prescribing
notes
under
Hepatic
Impairment
and
Renal
Impairment
and any advice
that
is
unique to a particular
drug in that
class
is
included in its individual drug monograph.
Prescribing for patients who are
pregnant or breast-feeding
Drug selection should aim to minimise harm to the
fetus,
nursing infant,
and mother.
The infant should be
monitored for potential side-effects of drugs used by the
mother during pregnancy or breast-feeding. The general
principles for prescribing are outlined under
Prescribing
in Pregnancy
(p.
19) and
Prescribing in Breast-feeding
(p.
19).
The prescribing notes
in the BNF chapters
provide guidance on the drug treatment
of
common
conditions that can occur during pregnancy and breast-
feeding (e.g. asthma, p.
170). Information about the use
of
specific drugs during pregnancy and breast-feeding
can
be
found
in
their
drug
monographs
under
Pregnancy
and
Breast-feeding
(e.g.
fluconazole,
p.
374).
However,
if a class of drugs (e.g.
tetracyclines,
p.
346) share the same recommendations for use during
pregnancy or breast-feeding, this advice is amalgamated
in the prescribing notes under
Pregnancy
and
Breast-
feeding
while any advice that is unique to a particular
drug in that
class
is
included in its individual
drug
monograph.
Minimising drug interactions
Drug selection should aim to minimise drug interac-
tions. If it is necessary to prescribe a potentially serious
combination of
drugs,
patients should be monitored
appropriately.
The mechanisms underlying drug inter-
actions are explained in Appendix 1 (p.
800).
Details of drug interactions can be found in Appendix 1
of
the BNF (p.
801).
Drugs and their interactions are
listed in alphabetical
order of the non-proprietary drug
name, and cross-references to drug classes are provided
where appropriate.
Each drug or
drug class is listed
twice:
in the alphabetical
list and also against the drug
or class with which it interacts. The symbol . is placed
against
interactions
that
are potentially serious
and
where combined administration of
drugs
should be
avoided (or only undertaken with caution and appro-
priate monitoring). Interactions that have no symbol do
not usually have serious consequences.
If a drug or drug class has interactions, a cross reference
to where these can be found in Appendix 1 is provided
under
the Cautions of
the drug monograph or
pre-
scribing notes.
Prescribing for the elderly
General
guidance on prescribing for the elderly can be
found on p.
24.
Prescribing for children
General
guidance on prescribing for
children can be
found on p.
15. For detailed advice on medicines used in
children, consult
BNF for Children
.
Selecting the dose
The drug dose is usually located in the
Dose
section of
the drug monograph or preparation record. The dose of
a drug may vary according to different indications and
routes of administration. If no indication is given by the
dose,
then that
dose can be used for
the conditions
specified in the Indications section of that drug mono-
graph, but not for the conditions cross-referring to other
sections of
the BNF.
The dose is located within the
preparation record when the dose varies according to
different
formulations of
that
drug (e.g.
amphotericin,
p.
378)
or when a preparation has a dose different
to
that
in its monograph (e.g.
Sporanox
c
liquid,
p.
376).
Occasionally,
drug doses may be included in the pre-
scribing notes for practical reasons (e.g.
doses of drugs
in
Helicobacter pylori
eradication regimens, p.
50). The
right
dose should be selected for the right
indication,
route of administration,
and preparation.
xii
BNF 61