BNF Interactions

In 2017 the BNF interactions were rewritten to be more consistently structured, allowing users to find interactions more easily, and giving more information about the severity and evidence of an interaction. All interactions are listed under individual drugs. When checking interactions for combination drugs or co-drugs, it is essential to refer to each drug in the combination. The interactions section of the drug monograph clearly states the drugs (or drug classes) that need to be referred to in the interactions (Appendix 1 in print).


Please note that co-trimoxazole currently has its own entry in print that does not include the interactions for trimethoprim. As stated above, it is essential to refer to both drugs (trimethoprim and sulfamethoxazole, under sulfonamides) to find all relevant interactions for this drug. This inconsistency will be corrected in the upcoming September editions, BNF 78 and BNF for Children 2019-2020. Digital products including MedicinesComplete and the BNF app have been corrected for the June monthly update.

For information on how to use the BNF, see How to use BNF publications. For more information on how to use the interactions content, see Appendix 1 Interactions.

Important notice to users of the iOS and Android BNF and BNFC Apps

Please ensure that you update your BNF app before you access the content. A fix has been made to correct a technical error that was resulting in some content not appearing. Online web versions of the BNF are unaffected.

The correct version to run for the December 2018 monthly update is 2.1.8 (iOS) and 2.1.11 (Android).

Please note that all digital platforms are updated every month. For the most up-to-date content and functionality, please ensure that you are using the latest version.

Clarification of the Doses at extremes of body-weight statement for vancomycin in BNF and BNF for Children

In July, BNF and BNF for Children digital products were updated in line with the SPC to recommend weight-based dosing of intravenous vancomycin. The ‘doses at extremes of body-weight’ section erroneously included a recommendation about dosing based on ideal body-weight. Note that the manufacturer recommends that intravenous weight-based doses for all patients should be based on total [actual] body-weight.

BNF and BNF for Children digital products will be updated to reflect this recommendation in both BNF and BNF for Children in the next scheduled update in mid-August.

Clarification of the parenteral dose of quinine for the treatment of malaria in BNF and BNF for Children

The maintenance dosing recommendations for parenteral quinine for the treatment of malaria have been updated in the BNF and BNF for Children digital publications. The requirement to reduce the maintenance dose to 5–7 mg/kg if parenteral treatment is needed for more than 48 hours has been added to all parenteral dose statements.

These updated recommendations will be present in the June monthly update for all digital products of BNF and BNF for Children; these changes will also be reflected in the print editions for BNF 76 and BNF for Children 2018-2019.

Clarification of dose of tramadol with paracetamol in BNF and BNF for Children

In light of a range of strengths now being available for combination tramadol-paracetamol preparations, the dose in BNF and BNF for Children has been updated in digital products.

The previous dose, expressed as tablets was not appropriate for the highest strength preparation (tramadol 75mg and paracetamol 650mg). The dosing has therefore been updated to express the dose in milligrams.

The new dosing has now been published in the tramadol with paracetamol monograph in digital versions of the BNF Publications.

Correction of dose of Ironorm® Drops in BNF for Children

The dose of Ironorm® Drops for the treatment of iron deficiency anaemia has been updated in the BNF for Children digital products.

The dose incorrectly stated a maximum volume per dose of 8mL, instead of a maximum volume per day of 8mL.

The correct dose is as follows:

Iron-deficiency anaemia (therapeutic)

By mouth

Child 1 month–5 years
0.12–0.24 mL/kilogram daily in 2–3 divided doses; maximum 8 mL per day.

Child 6–11 years
0.12–0.24 mL/kilogram daily in 2–3 divided doses; maximum 8 mL per day.

Child 12–17 years
4 mL 1–2 times a day.

This updated dose will be present in the October monthly update for all digital products of BNF for Children.

Update to nystatin dose in BNF and BNF for Children

The nystatin dose for oral candidiasis in the BNF has historically reflected the posology recommendations in the Nystan® Summary of Product Characteristics (SPC). Following discussions with the MHRA the dose has been updated (live in digital versions of the BNF from March 2017) and now reflects current posology recommendations for generic nystatin products.

Ceftriaxone: substantial changes to indication and dose statements and directions for administration to reflect the updated Summary of Product Characteristics (SPC) for Rocephin®

Ceftriaxone has undergone substantial changes which are live in digital versions and will appear in print in BNF for Children 2016-2017 and BNF 72. These changes reflect the updated Summary of Product Characteristics (SPC) for Rocephin® and also advice and feedback from expert opinion and the BNF formulary committees.

Indication and dose

Indications and doses have been separated out. The umbrella term of “Susceptible infections due to sensitive Gram-positive and Gram-negative bacteria” has been removed in preference of individual indications and dosing depending on the indications.

Children 1 month-11 years on mg/kg dosing can get a higher dose than children from 12 years on standard dosing

Doses for the European Summary of Product Characteristics were amended following consultation with the European Medicines Agency. In adults and children over 12 years of age, the recommended dose varies between 1 g and 4 g once daily depending on the indication. In children below 12 years of age, the recommended dose depends on both the body-weight of the patient and the indication. The full details behind these changes are available here:

Why has the age range Child 911 years (body-weight 50 kg and above) been chosen?

The SPC for Rocephin® states that a child 1 month–12 years with a body-weight over 50 kg should be dosed as for those of 12 years and above. However, the majority of children under 12 years will not weigh over 50 kg, therefore expert advice was taken to determine an appropriate age range of those under 12 years who may weigh above 50 kg. The age range of “Child 9–11 years (body-weight 50 kg and above)” was considered appropriate.

Route and Directions for Administration

The routes of administration have been split out to encourage the use of intravenous infusion as a first choice over other routes. It is important to read the Directions for Administration section before prescribing, clinically checking or administering ceftriaxone by a certain route.

The SPC for Rocephin® states that intravenous doses of 50 mg/kg or more in infants and children up to 12 years of age should be given by infusion only; in the light of this, the ceftriaxone monograph does not give the option of administration by intravenous injection in children 1 month–11 years and body-weight up to 50 kg. Where doses via intravenous infusion are not possible, doses can be given by deep intramuscular injection in the manner described under Directions for Administration.

As patients aged 9–11 years (body-weight 50 kg and above) may rarely receive doses less than 50 mg/kg, the option to administer the dose by intravenous injection is retained.

All children, excluding neonates, can receive ceftriaxone by deep intramuscular injection. The Directions for Administration should be followed when administering deep intramuscular injection in children.

Update and clarification of ceftriaxone in the BNF for Children 2015-2016

Following feedback about the ceftriaxone monograph in BNFC 2015-2016 and online, we would like to provide an update and clarification:

In the current BNFC, the dosage and route of ceftriaxone remains unchanged from BNFC legacy. Although the routes for the dosing statement include intramuscular injection, this was never intended as a recommendation for child under 12 years with body-weight under 50kg, as doses of 50mg/kg and over were advised to be given by intravenous infusion only. Children over 50kg do have the option in this dosing statement to have ceftriaxone by intramuscular injection. However, since this information has been published, the SPC for Rocephin has been updated.

Over the last few months, we have been processing the updated SPC and we have also taken the opinion of expert advisers, the Paediatric Formulary Committee, and now are awaiting evidence from the manufacturer. This is to ensure the content we publish is clinically appropriate for paediatrics.

We appreciate the need to update the monograph based on the SPC as soon as possible, but we also want to ensure the dose and route are safe and appropriate before the monograph will be published.