Can I use this Nitroglycerin 6.4mg Tablet CR the same way as a sublingual nitroglycerin tablet?

This is an important distinction to catch the tablet you're asking about is a controlled-release (CR) form, meant to be swallowed whole and absorbed slowly over hours to prevent angina, not placed under the tongue for quick relief during an episode of chest pain. Sublingual nitroglycerin is a completely different, fast-acting formulation used specifically for sudden symptoms. Please don't substitute one for the other without your doctor's guidance, since using the wrong form at the wrong moment could leave you without the rapid relief you might need.