SZ1676 is the 3-acetoxy derivative. The neuromuscular (NM) effects of SZ1676 and SZ1677 are compared in beagle dogs. SZ1677 (ED 90 =19.2±2.6 μg/kg) is 1.86 times more potent than SZ1676 (ED 90 =35.8±2.5 μg/kg).