The most important things that both veterinary surgeons and farmers need to remember include the legal framework in which we use medicines, the importance of considering antimicrobial resistance (AMR) and the risks of residues entering the food chain. In his talk, Professor Barrett also touched on antimicrobial use targets and monitoring and recording as they relate to on-farm medicine use and future uncertainty in-cluding changes after the Brexit transition period ends at the end of 2020.
Responsible use of medicines encompasses many things including the consideration of antimicrobial resistance, anthelmintic resistance, animal health and welfare, food quality and safety and safeguarding the food supply, environmental impacts and various aspects of veterinary public health. The Veterinary Medicines Regulations set out legal text on the manufacture, authorisation, marketing, distribution and post-authorisation surveillance of veterinary medicines and are implemented by the Veterinary Medicines Directorate (VMD) an executive agency sponsored by the Department for Environment Food & Rural Affairs (Defra). Professor Barrett discussed this and the veterinary medicine distribution categories, focusing mainly on Prescription Only Medicines in both the veterinarian (POM-V) and veterinarian, pharmacist and SQP (POM-VPS) classifications.
There was then considerable discussion on the importance and implementation of The Pre-scribing Cascade, in particular what constitutes legal use of veterinary medicines.
- Authorised use is where a product is used in accordance with the medicine's Marketing Authorisation summarised in the clinical advice given on the pack leaflet/data sheet or Summary of Product Characteristics (SPC).
- Cascade use is where a veterinary surgeon may choose to administer a product outside the terms of the Marketing Authorisation. This includes using a different dose regimen, a different duration of treatment, use for a condition other than specified on the pack leaflet/data sheet, or use in another species. The Cascade allows veterinary surgeons to use clinical judgement and treat animals under their care guided by a risk-based decision tree. Cascade use may only be under the authorisation and direction of the prescribing veterinary surgeon.
The point was then made that any other use of veterinary medicines outside the constraints of the Cascade would be considered illegal use, for example when a farmer chooses to use a medicine outside the direction of the SPC (or data sheet) and without specific direction of a veterinary surgeon. The point was also made that this direction or authorisation needs to be on a case-by-case basis and should not be a general direction to use a medicine in this way, for example written into a herd health plan.
The focus then turned to AMR and the classification of some antimicrobials being highest priority critically important (HPCIA), as defined by the World Health Organisation or the European Medicine Agency (EMA). There was then discussion of recently introduced new EMA medicine categorisation, with all antibiotics being placed into one of four categories:
- Category A (‘Avoid’) includes antibiotics that are currently not authorised in veterinary medicine in the European Union (EU)
- Category B (‘Restrict’) refers to quinolones, 3rd- and 4th-generation cephalosporins and polymyxins (previously called HPCIA)
- Category C (‘Caution’) covers antibiotics for which alternatives in human medicine generally exist in the EU, but only few alternatives are available in certain veterinary indications
- Category D (‘Prudence’) includes antibiotics that should be used as first-line treatments, whenever possible. These antibiotics can be used in animals in a prudent manner.
Professor Barrett then drew attention to medicine recording and traceability as well as reported data on national and international antimicrobial use and usage targets as published by ESVAC, VARSS and RUMA.
The presentation concluded with a brief discussion on a practical approach to prescribing and medicine administration decision making.