How to use the British National Formulary
Oliver Jones explains how the BNF can become your best friend
Scenario: You have just qualified. It's
3 am and you are on your own in
the ward. You have five emergency
admissions to deal with. Some patients
cannot remember what drugs they are
on. The others have brought all their
drugs with them. You have to sort out
their medication.
The British National Formulary (BNF)
is a joint publication by the British
Medical Association and the Royal
Pharmaceutical Association. The book is
published under the authority of the Joint
Formulary Committee, which in turn
seeks advice from a panel of experts. It is
also available on the web at
http://BNF.org. As a biannual publication
the BNF should be considered both
impartial and up to date. This article summarises
how to maximise the efficient use
of this reference manual.
Stage 1: finding the drug
The heart of the BNF comprises 15 chapters,
listed on the contents page, of conditions,
drugs, and preparations divided
by organ-for example, cardiovascular
system-or medical condition-for example,
infections. When searching for a
drug, the most efficient method is to turn
straight to the index and look up either
the brand name-for example,
Epanutin-or the generic name-for
example, phenytoin-of the drug. Both
should be in the index. The BNF is comprehensive
and includes even those
drugs it considers less suitable, marked
with the symbol . However, it may
not list those medicines promoted for
purchase by the public.
Stage 2: a background to the condition
Individual drugs are listed in sections
with others similar either in chemical
structure or clinical indication. At the
beginning of each section, there is usually
a concise summary of the clinical condition,
the pharmacological options, and
the weight of evidence for relative drug
efficacy. This information can be useful in
confirming the suitability of the drug that
has been chosen, but also occasionally
redirects the prescriber to a related alternative
better for the specific indication in
question.
Stage 3: indications for the drug and its safety
All drugs are listed in identical fashion, as
shown on page vi of BNF 41 (March
2001). Unlicensed indications are included
for some drugs - for example, GTN
ointment for anal fissure - but where this
occurs, it is clearly stated. Cautions and
contraindications for each drug may refer
to the appendices at the end of the BNF.
Appendix 1 is an alphabetical list of drug
interactions, where the symbol l denotes
a potentially serious interaction.
Reference is also frequently made to
appendices 2 and 3, which give further
information on prescribing for patients
with hepatic and renal impairment
respectively, while appendices 4 and 5
advise on drug prescribing in pregnancy
and to patients who are breast feeding.
Stage 4: dose and route of administration
Route of administration is obviously a
clinical decision. However, both this and
whether the patient is a child or is elderly
may affect dose, and should be checked
carefully.
Stage 5: selecting the brand of drug
Prescribing generically allows the pharmacist
to dispense what is available in the
pharmacy, increasing the likelihood of
the patient being able to start treatment
immediately. The pharmacist may substitute
cheaper formulations if appropriate.
It is worth noting that the prices listed in
the BNF do not correspond precisely to
the cost to the NHS, nor do they represent
the cost of private prescriptions or of
purchasing the drugs over the counter.
Getting the most from the BNF
There is a wealth of additional information
in the BNF that serves as a prompt
for the clinician. Some of these, with page
numbers in BNF 41 (March 2001), are listed
below.
- Guidelines on permitted and prohibited
substances in sport (with addresses
and telephones numbers for more
information): 19.
- Guidance notes for prescribing for the
children and the elderly: 11-2 and 17-8.
- Prescribing in palliative care, including
a useful table for converting oral morphine
requirements into parenteral
diamorphine: 13-7.
- Telephone numbers for the poisons
information centres and paracetamol
overdose treatment graphs: 20-9.
- A stepwise management plan for the
treatment of acute and chronic asthma
based on the British Guidelines on
Asthma Management: 132-3.
- A basic summary of the fitness to drive
guidelines for patients with epilepsy: 225.
- Information on various aspects of prophylaxis.
This includes antibacterial prophylaxis
for prevention of endocarditis
in at risk patients (with heart valve
lesions, congenital heart abnormalities,
and prosthetic valves) undergoing interventional
procedures: 254-6.
- Details of antimalarial prophylaxis recommendations
for international travellers
and addresses and telephone
numbers for further health advice and
immunisation: 306-9.
Oliver Jones, research fellow, department of pharmacology, University of Oxford
Email: oliver.jones@pharm.ox.ac.uk
Back editions of the BNF can be put to use. An
organisation called Pharmaid dispatches old
copies (even those six to 12 months old) to
Commonwealth countries. These can usually be
handed in at local collection points (most hospital
pharmacies will be able to provide guidance
on this). Alternatively, contact Betty
Falconbridge on 0202 7735 9141, ext 281, or bfalconbridge@rpsgb.org.uk
studentBMJ 2001;09:217-260 July ISSN 0966-6494
