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.