Taking 5 mg/day of isosorbide monotrite. does its long term usage deplete or has affect on nitric oxide in arteries. any tapering off needed.?

Problematic: Long acting nitrates exhibit tachyphylaxis which means that the more you take, the less they work. Moreover, there is a rebound issue when you stop them abruptly. That said, people who only take nitrates once a day will not be affected by either issue because the med wears off and they are effectively only receiving 8-12 hours of nitrate effect in any 24 hour period.