Excise classification change: Rifampicin exempted; other bulk drugs now subject to ad valorem duty under revised notification. The Government amends Notification No. 31/88-C.E. to create a separate entry granting Rifampicin a nil excise rate and to subject other bulk drugs, not including specified items, to an ad valorem duty, thereby changing tariff classification and applicable duty treatment within the miscellaneous exemptions schedule.