2004 Annual Scientific Meeting - CLICK FOR PROGRAMME

TCI – Diprifusor and beyond

Dr Douglas Russell, Consultant Anaesthetist, Southern General Hospital, Glasgow G51 4TF.

Collaboration between AstraZeneca Pharmaceuticals and the University of Glasgow Department of Anaesthesia led to the development of the ‘Diprifusor’ target-controlled infusion (TCI) system for propofol, introduced to the UK in 1996 [1]. More than 10,000 Diprifusors have since been introduced to over 25 countries throughout the world, AstraZeneca received a Queen’s Award for technological innovation, and at least 13 million propofol anaesthetics have been delivered by TCI worldwide. A notable exception is the United States of America, where there has been no progress towards FDA approval, mainly due to the lack of a regulatory precedent for the drug-device combination [2]. With propofol now available in the UK as a generic preparation drug costs have decreased, but the cost of tagged glass pre-filled syringes required for Diprifusor TCI has not; indeed in the author’s own hospital Diprivan pre-filled syringe costs have recently increased.

A number of infusion device manufacturers have introduced “open” TCI systems for propofol, remifentanil and sufentanil, and information about these can be found on the links page of the SIVA UK website [3]. These new devices are CE marked, to which there are a number of routes. If a company believes that their device meets so called “essential requirements” of performance and safety, and if they have an approved quality system in house, they do not need to submit their device for external evaluation by a statutory body. The medical device regulations do not require any collaboration between device and drug manufacturers, and one could argue that this should be required, to ensure that the device contains an appropriate pharmacokinetic model [4]. Currently (November 2004) in the UK, the only drug that is licensed for administration by TCI is propofol, from Diprifusor TCI systems. Use of “open” TCI systems could be considered as “off label” drug administration, although if drug delivery rates achieved in TCI mode fall within those advocated in existing labelling for (manual) bolus and infusion dosing it could be argued that delivery is in accordance with the prescribing information.

With many Diprifusor TCI systems approaching 10 years old, and with TIVA still perceived by some as an expensive technique, “open” systems can administer propofol by TCI at a fraction of the cost of using Diprivan pre-filled syringes, and remifentanil and perhaps other drugs by TCI. It may be possible to purchase new infusion systems using the projected savings from administering generic propofol instead of using pre-filled Diprivan syringes. The features of these new devices will be presented and discussed.

 References:

1. Target Controlled Intravenous Anaesthesia using ‘Diprifusor’. Anaesthesia 1998; 53(Suppl 1).

2. Egan TD, Shafer SL. Target-controlled Infusions for Intravenous Anesthetics. Surfing USA Not! Anesthesiology 2003;99:1039-41.

3. SIVA UK – The UK Society for Intravenous Anaesthesia; http://www.sivauk.org

4. Personal communication, Dr JB Glen, Glen Pharma, Knutsford, Cheshire.