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Investigation of escalating and large bolus doses of a novel, nano-droplet, aqueous 1% propofol formulation in cats


William W Muir, 338 W. 7th Ave., Columbus, OH 43210, USA. E-mail: bill.muir@amcny.orgPresent address: Ashley J Wiese, Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave, Davis, CA 95616, USA


Objective  Identify, describe, and quantitate effects of an escalating dose of a nano-droplet formulation of 1% w/v propofol in telemetered cats.

Study design  Prospective two-period parallel design with one treatment procedure per period.

Animals  Four female intact, purpose-bred domestic short-hair cats.

Methods  Each animal served as its own control in each period. Telemetered cats were anesthetized on two separate occasions. In Phase I, cats received propofol (8 mg kg−1) over 90 seconds. Unless a severe adverse event (SAE) had occurred by this time, repeated doses of 4 mg kg−1 intravenous (IV) propofol were administered every 3 minutes until the onset of an SAE. In Phase 2, the IV dose of propofol required to produce at least one SAE in Phase I was administered unless an SAE occurred before the dose was completed. Propofol infusion ceased after development of the first SAE. Heart rate, heart rhythm, respiratory rate, systolic, diastolic, and mean arterial blood pressure, SpO2 and body temperature were continuously recorded before, during and after propofol administration. The incidence and time to onset of an SAE and dose of propofol required to produce an SAE were recorded. The response criteria included time to lateral recumbency, times to orotracheal intubation and extubation, time to sternal recumbency during recovery, time to and duration of first adverse event(s), and total dose of propofol administered.

Results  The dose of propofol required to produce an SAE in Phase I was 16.6 and 15.2 mg kg−1 in Phase 2. Hypotension was the first and most frequently observed SAE.

Conclusions  Larger doses of a novel, nano-droplet propofol formulation can produce SAEs similar to those reported for lipid emulsion formulations.

Clinical relevance  Systemic arterial blood pressure should be monitored in cats administered IV propofol.