Acute Cardiorespiratory Effects of PS1, an Antineoplastic Glucan, in Rats

PS1 is a high molecular weight glucan extracted from Bacillus Calmette–Guerin (BCG) vaccine. It has demonstrated considerable in-vivo antineoplastic activity, apparently without associated toxicity. Toxicity of the BCG vaccine used in the clinical treatment of human superficial bladder cancer has been associated with the use of a viable mycobacterial preparation; an active extract would be anticipated to have less toxicity but has to be tested. Most toxicity tests require considerable quantities of the test material which in this case are currently not available. Accordingly, an in-vivo study of the effects produced on blood gases, haemoglobin and pulse and breathing rates after intravenous administration 5 μg kg−1 PS1 was carried out using cannulated rats and a sensitive methodology developed for other purposes. Following the various parameters for up to 1 h after administration showed no significant deviation from baseline values obtained before injection. PS1 at a dose of 5 μg kg−1 had no observable acute toxicity in rats. Nevertheless, chronic effects at this and higher doses have to be determined before more conventional toxicity testing is carried out.