BNF 84 (British National Formulary) September 2022

In earlier editions (i.e. before BNF 70), a systemically

administered drug with indications for use in different body

systems was split across the chapters relating to those body

systems. So, for example, codeine phosphate p. 487 was

found in chapter 1, for its antimotility effects and chapter 4

for its analgesic effects. However, the monograph in chapter

1 contained only the dose and some selected safety

precautions

Now, all of the information for the systemic use of a drug is

contained within one monograph, so codeine phosphate

p. 487 is now included in chapter 4. This carries the

advantage of providing all of the information in one place, so

the user does not need to flick back and forth across several

pages to find all of the relevant information for that drug.

Cross references are included in chapter 1, where the

management of diarrhoea is discussed, to the drug

monograph to assist navigation.

Where drugs have systemic and local uses, for example,

chloramphenicol, and the considerations around drug use

are markedly different according to the route of

administration, the monograph is split, as with earlier

editions, into the relevant chapters.

This means that the majority of drugs are still placed in the

same chapters and sections as earlier editions, and although

there may be some variation in order, all of the relevant

information will be easier to locate.

One of the most significant changes to the monograph

structure is the increased granularity, with a move from

around 9 sections to over 20 sections; sections are only

included when relevant information has been identified. The

following information describes these sections and their uses

in more detail.

Nomenclature

Monograph titles follow the convention of recommended

international non-proprietary names (rINNs), or, in the

absence of a rINN, British Approved Names. Relevant

synonyms are included below the title and, in some

instances a brief description of the drug action is included.

Over future editions these drug action statements will be

rolled out for all drugs.

In some monographs, immediately below the

nomenclature or drug action, there are a number of cross

references or flags used to signpost the user to any

additional information they need to consider about a drug.

This is most common for drugs formulated in combinations,

where users will be signposted to the monographs for the

individual ingredients (e.g. senna with ispaghula husk p. 65)

or for drugs that are related to a drug class monograph (see

Drug class monographs, p. xv).

Indication and dose

User feedback has highlighted that one of the main uses of

the BNF is identifying indications and doses of drugs.

Therefore, indication and dose information has been

promoted to the top of the monograph and highlighted by a

coloured panel to aid quick reference.

The indication and dose section is more highly structured

than in earlier editions, giving greater clarity around which

doses should be used for which indications and by which

route. In addition, if the dose varies with a specific

preparation or formulation, that dosing information has

been moved out of the preparations section and in to the

indication and dose panel, under a heading of the

preparation name.

Doses are either expressed in terms of a definite frequency

(e.g. 1 g 4 times daily) or in the total daily dose format (e.g.

6 g daily in 3 divided doses); the total daily dose should be

divided into individual doses (in the second example, the

patient should receive 2 g 3 times daily).

Doses for specific patient groups (e.g. the elderly) may be

included if they are different to the standard dose. Doses for

children can be identified by the relevant age range and may

vary according to their age or body-weight.

In earlier editions of the BNF, age ranges and weight

ranges overlapped. For clarity and to aid selection of the

correct dose, wherever possible these age and weight ranges

now do not overlap. When interpreting age ranges it is

important to understand that a patient is considered to be 64

up until the point of their 65th birthday, meaning that an age

range of adult 18 to 64 is applicable to a patient from the day

of their 18th birthday until the day before their 65th birthday.

All age ranges should be interpreted in this way. Similarly,

when interpreting weight ranges, it should be understood

that a weight of up to 30 kg is applicable to a patient up to,

but not including, the point that they tip the scales at 30 kg

and a weight range of 35 to 59 kg is applicable to a patient as

soon as they tip the scales at 35 kg right up until, but not

including, the point that they tip the scales at 60 kg. All

weight ranges should be interpreted in this way.

In all circumstances, it is important to consider the patient

in question and their physical condition, and select the dose

most appropriate for the individual.

Other information relevant to Indication and dose

The dose panel also contains, where known, an indication of

pharmacokinetic considerations that may affect the

choice of dose, and dose equivalence information, which

may aid the selection of dose when switching between drugs

or preparations.

The BNF includes unlicensed use of medicines when the

clinical need cannot be met by licensed medicines; such use

should be supported by appropriate evidence and

experience. When the BNF recommends an unlicensed

medicine or the ‘off-label’ use of a licensed medicine, this is

shown below the indication and dose panel in the unlicensed

use section.

Minimising harm and drug safety

The drug chosen to treat a particular condition should

minimise the patient’s susceptibility to adverse effects and,

where co-morbidities exist, have minimal detrimental effects

on the patient’s other diseases. To achieve this, the Contraindications, Cautions and Side-effects of the relevant drug

should be reviewed.

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 Cautions 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 Important safety advice section in the BNF, delineated

by a coloured outline box, highlights important safety

concerns, often those raised by regulatory authorities or

guideline producers. Safety warnings issued by the

Commission on Human Medicines (CHM) or Medicines and

Healthcare products Regulatory Agency (MHRA) are found

here.

Drug selection should aim to minimise drug interactions.

If it is necessary to prescribe a potentially serious

combination of drugs, patients should be monitored

appropriately. The mechanisms underlying drug interactions

are explained in Appendix 1, followed by details of drug

interactions.

Use of drugs in specific patient populations

Drug selection should aim to minimise the potential for drug

accumulation, adverse drug reactions, and exacerbation 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 adjustments should be made,

and patients should be monitored adequately. The general

principles for prescribing are outlined under Prescribing in

hepatic impairment p. 20, and Prescribing in renal

impairment p. 21. Information about drugs that should be

avoided or used with caution in hepatic disease or renal

impairment can be found in drug monographs under Hepatic

impairment and Renal impairment (e.g. fluconazole p. 649)