Lidocaine - shelf life; after opening?

I wonder what your take is on duration of storage of medications (vials and ampoules) after they are opened. I have heard from some collegues, that for antibiotic ampoules it should be used not longer than 24hours once opened, vials should be discarded after once use irrespective of dose required. (This has become the practise in the hospital i work, as an infection control measure). Nothing was said of medications like, the 2% lidocaine injection with antimicrobial additive (not mentioned) and some others. Could you give me an evidence based response to shelf life of medications in ampoules and vials.

I have the same question about the life of lidocaine after opening vial or ampule. 1% Lidocaine injectible solution preservative free 30ml vial. My other question is, can you use it on multiple patients? Yes we have read all information on the insert that comes with it.