CT1341 is a mixture of two steroids dissolved in cremophor EL (table 1). The results of studies in animals show that it is a rapidly acting intravenous induction agent with a high therapeutic index and is free from irritant effects when injected intravascularly 1. Initial studies in man2-5 have confirmed the animal findings, but its action on the cardiorespiratory system has not been previously fully investigated and therefore, in this study, measurements of the cardiorespiratory effects of CT1341 were undertaken in fit, unpremedicated patients prior to surgery. Electroencephalographic (EEG) changes and biochemical effects were also studied. METHODSThe purpose of the investigation was explained to the patients pre-operatively and written consent was obtained for the insertion of the arterial and venous cannulae, which were required for measurement of blood pressure, central venous pressure (CVP) and cardiac output. The patients were divided into three groups (table 2). Two standard dosages based on observations from animal studies1 were used and, in the case of the lower dosage, two rates of injection were employed.