Sounds like he "doth protest too much!" So does your management plan to write you up, or is this bothering you more for the fact that he is running around lying about it to everyone?
That place sounds kinda dysfunctional with all that going on...not the least of which is "nursing doses" - - people surely are insane if they are doing that these days, and besides, if it was a one-time order, any subsequent administration of the same is way more than what a "nursing dose" ever was anyway, as I understand the concept. Nursing doses are illegal...just to throw that in there.
its is unrealistic to always have another nurse to witness the phone conversation especially when we have emergency situations requiring immediate call
I hear you, but that can't be the case any more. Unless your emergencies involve pending arrest then I guess it can wait until someone can witness anything this jerk says. And that's true for ALL telephone orders, whether you trust the ordering provider or not. I don't like feeling like I have no compassion, but the stakes are high as you've found out. So I guess we must all play by the rules all the time. I learned this lesson early on, the same way you're learning it...I had an MD deny having given me a verbal order after the patient had an adverse effect due to the order. It got ugly, and I won. "Fool me once...."
Sorry this is happening to you. What to do about it really depends on whether your management plans to let it blow over or not.