thiazepine thiazepine thiazepines are substituted thiepins, with a nitrogen replacing a carbon in the seven-membered heterocyclic compound. depending on the location of the nitrogen, one distinguishes 1,3-thiazepine and 1,4-thiazepine. 1,3-thiazepine 1,4-thiazepine diltiazem. 1,4-thiazepine is the seven membered ring in the middle. benzothiazepines have a single benzene attached to the ring, while dibenzothiazepines have two. diltiazem, a benzothiazepine, is a calcium channel blocker intermediate in properties between verapamil and the dihydropyridines. it is used to treat variant angina (prinzmetal's angina), either naturally occurring or drug-induced and stable angina.