The following abstracts were presented at the Annual Scientific Meeting of the UK Society for Intravenous Anaesthesia in Cambridge, December 2007 Pharmacokinetics and anaesthetic effects of propofol-PM: a novel water soluble propofol formulation A. E. Rigby-Jones, 1 J. R. Sneyd, 1 F. Ravenelle, 2 P. Vachon, 2 D. Le Garrec, 2 S. Gori, 2 D. Lessard 2 and D. C. Smith 2 1 Peninsula Medical School, Plymouth, UK 2 Labopharm Inc., QC, Canada We have investigated the use of amphiphilic diblock copolymers of poly (N-vinyl-2-pyrrolidone) and poly- (D,L-lactide), PVP-PLA, to dissolve propofol inside micelles (30–60 nm) – Propofol-PM. We compared the pharmacokinetics (PK) of propofol in blood and plasma when administered as 1% Diprivan and as three 1% solutions reconstituted from Propofol-PM 7, 10 and 12% respectively. We also undertook a preliminary pharmaco- dynamic (PD) study. Methods Forty male Sprague–Dawley rats (325 ± 10 g) were randomly allocated to one of eight groups (five rats ⁄ group). Ten rats were used for each of the four propofol formulations: five rats for the collection of whole blood and five for plasma. The rats were anaesthetised with isoflurane and both jugular veins exposed. Isoflurane was then discontinued. When the animals responded to a hind paw pinch, they received propofol 10 mg.kg )1 (1 ml.kg )1 over 1 min) via the jugular vein. Blood samples were collected at 1, 3, 5, 7.5, 10, 15, 30, 60 and 75 min after injection. A PK model was constructed using NONMEM software. Animal weight, sample matrix (blood or plasma) and propofol formulation (Diprivan, Propofol-PM 7, 10 and 12%) were evaluated as model covariates. In a separate small PD study, the times of the recovery endpoints (leg withdrawal, first movement, righting) were compared for the four propofol formulations. All experiments were conducted in accordance with guidelines from the Canadian Council on Animal Care and the Use of Laboratory Animals, and a certificate of conformity granted. Results The optimal PK model had two compartments and incorporated sample matrix and propofol formulation as dichotomous covariates (Fig. 1). Sample matrix was applied to all structural parameters. An influence of propofol formulation was observed for all structural model parameters (excluding distributional clearance) but only when plasma was used as the sample matrix. The effect of formulation was not apparent when whole blood concentrations of propofol were measured. Discussion The whole blood PK of Propofol-PM did not differ from that observed with Diprivan. We observed lower propo- fol concentrations in plasma samples after Propofol-PM administration than after Diprivan but the quantity of the copolymer in the Propofol-PM formulations did not influence the PK. Although there was no statistically Figure 1 The average model predicted profiles. Error bars show ± 1 SD. Publication of these abstracts is on the understanding that they meet the rules for publication of abstracts presented at specialist society meetings, which may be found in the general Instructions to Authors in the Jan issue of Anaesthesia or on the journal’s website (http://www.blackwellpublishing.com/ submit.asp?ref=0003-2409). Anaesthesia, 2008, 63, pages 1392–1394 doi:10.1111/j.1365-2044.2008.05646.x ..................................................................................................................................................................................................................... 1392 Ó 2008 The Association of Anaesthetists of Great Britain and Ireland