Stability of I-653 in soda lime

Stability is an important characteristic of a halogenated volatile anesthetic because breakdown may produce toxic compounds. The resistance to breakdown by soda lime of a new halogenated volatile anesthetic, I-653, was compared with the resistances found for halothane, isoflurane, and sevoflurane. The four anesthetics were injected concurrently into flasks containing 500 ml of gas and 100 g of soda lime maintained at 40, 60, and 80 degrees C. Four or five flasks were tested at each temperature. The rate of anesthetic degradation increased as temperature increased. Degradation was greatest with sevoflurane and least with I-653. At 80 degrees C, the rate of degradation per hr was 92.2 +/- 5% with sevoflurane; 16.0 +/- 1.6% with halothane; 13.1 +/- 3.7% with isoflurane; and 0.44 +/- 0.26% with I-653 (means +/- SD). The in vitro stability of I-653 suggests that it may strongly resist biodegradation.