Could my patient get vancomycin toxicity?

I was working the night shift last night on a busy surgical unit, taking care of a total knee patient. A fairly healthy, overweight lady, 71, no history of kidney issues. Well... the doctor ordered vancomycin 1gm IV Q12H x2 doses which is a standard order post surgery just to help prevent infection. During my shift, I was to give the 2nd and last dose.

Now I am not a whistleblower and I don't "tattle" or look to get my co-workers in trouble. I gave my dose at its scheduled time. A few hours later I was going through my patient's MARs and I noticed the first dose had been given only 8 hours previously before the dose of vancomycin I hung on the patient. I don't know the circumstances of why it was late, but she got her 2 doses of vanc 8 hours apart rather than 12 because of this. Is my patient at any risk - I am not the best at pharmacology or how much it takes to be harmful to a patient if given the wrong dose - and what would you do, should I go to my supervisor and let her know a/b this?
I would not worry too much. Two doses of 1 gm 8 hours apart in a patient with healthy kidneys is not all that much. In the setting of sepsis, I have given a 1750mg load in a single dose, to give you some perspective. Your total of 2 gm over an 8 hour period should be ok, especially considering it isn't going to be an ongoing regimen -- but that is only an educated guess on my part. There are ways to check for sure though, and they would be 1. get a vanco level and 2. consult your hospital pharmacist re: pharmacokinetics and whether or not this is likely going to be an issue in the setting of her renal function numbers. I think a pharmacist would be better prepared to give you a definitive answer.

no worries if her kidney functions are normal i wouldn't worry...

Probably not to worry. More important - why wasn't it passed on about the time the first dose was given so you would know when 12 hours had passed?

I also wouldn't worry, but there needs to be better communication with dosage times. I would never ever assume a first dose is given on time. Because I rarely give first doses at the time pharmacy puts on our MARs. Most of the time the drug isn't on the floor from pharmacy at the time on the MAR. Lots of times the patient isn't even on the floor yet.I'd be worried if this isn't communicated that perhaps there are other miscommunications going on. Probably not a big deal in this case (assuming normal renal function) but could be in the future with another medication.

Vancomycin is usually dosed based on weight and creatine clearance. Two doses of Vanco 8 hrs apart is very unlikely in a overweight patient to cause any complications but should be reported to your supervisor.