The action of G.29.505 on the respiration of the rabbit.

Most anaesthetists would agree that there is room for a more satisfactory intravenous anaesthetic than thiopentone. This drug is a powerful depressor both of blood pressure and of respiration. The compound G.29.505 was investigated in the laboratory by Thuillier and Domenjoz (1957), and appeared to offer some promise, particularly because of some tendency on its part to stimulate respiration. Frey and Hermann (1957), and later Henschel and Just (1957), confirmed that this respiratory stimulant effect occurred in the human subject. Swerdlow (1961) found that anaesthesia with G.29.505 terminated rapidly and left no hangover. Dundee and Hamilton (1960) showed that this drug lacked the anti-analgesic action of thiopentone and the barbiturates generally. All who have used the drug, however, have found that it tends to produce extensive thrombophlebitis in a small proportion of cases (Payne and Wright, 1962; Swerdlow, 1962). As this complication can involve obliteration of most of the veins in the limb into which the drug is injected, it must be regarded seriously, and before G.29.505 can find general acceptance it must be shown to possess very considerable advantages over thiopentone to outweigh the risk that it may provoke this complication. It is the view of the author that prompt recovery and a lack of anti-analgesic action are not in themselves sufficient to justify a change-over If, however, it could also be shown that the drug had substantially no effect on respiration it would add to its claim to be used more widely. With this in view the action of G.29.505 on the respiration of the rabbit was studied.