Effect of methyl substitution on the irritancy of dibenz[b,f]1,4-oxazepine(CR).

The irritant properties of 3 methylated derivatives of dibenz[b,f]1,4-oxazepine (CR) have been investigated, using the guinea-pig blepharospasm test and isolated cat eye preparations, and compared with the irritancy of the unsubstituted CR molecule. In both tests, the 11-methyl derivative was non-irritant whereas 3 Me-CR and 9 Me-CR retained some irritancy although both were less potent than CR itself. The possible significance of these results are discussed in relation to earlier biochemical studies.