The sporocidal activity of 1% solutions of five local anaesthetics and five preservatives (cetrimide, chlorocresol, chlorhexidine, phenoxyethanol and phenylmercuric nitrate) a t their pharmacopeial concentrations, alone and in binary combinations was determined against Bacillus subtilis and Aapergillus niger spores at different temperature levels by the surface viable count technique. The sporicidal activity of all tested systems were temperature dependent. A . niger spores were much more sensitive to the tested systems than B. aubtilia spores. The temperature a t which 99% of all spores were killed after 30 min exposure time of the anaesthetics were calculated. In case of the local anaesthetics alone against spores of A . niger the recorded temperatures were 30 "C for amethocaine, 45 "C for both amylocaine and cincochaine, 48 "C and 50 "C for lignocaine and procaine, respectively, in contrast to 58 "C in a control with saline solution. Much higher temperatures were calculated against B. aubtilis spores. Cincochaine was the most effective local anaesthetic with a recorded temperature of 60 "C, where 99% killing occurred. Amylocaine and amethocaine showed temperatures of 84 "C and 90 "C, respectively. Procaine, lignocaine as well saline solution as a control caused a 99% killing effect a t temperatures higher than 100 "C.
Among the 25 tested binary combinations of local anaesthetics and preservatives, the highest incidence of potentiation of the sporocidal activity was recorded with chlorocresol combinations, while other combinations of the four remaining preservatives showed different types of interactions a t different percentages.