These are similar but not exactly the same mechanism of action.
Diethylene glycol dinitrate
Glyceryltrinitrate (nitroglycerin)
Isosorbidemononitrate and dinitrate
Itramintosilate
Nicorandil (which additionally acts as a potassium channel opener)
Pentaerithrityltetranitrate
Propatylnitrate
Sinitrodil
Tenitramine
Trolnitrate
You should see a doctor, preferably a cardiologist, to discuss possible alternatives/substitutes for Nikoran OD. He/she will be able to give you the proper dosing, make sure there are no contraindications with your other co-morbidities, and make sure there are no unwarranted interactions with other drugs you are currently taking.