Never assume ANYTHING. That's one of the first things you learn in nursing school.
NEVER assume anything. Don't forget that.
Never ASSUME anything. As the nursing instructors say, when you assume you make an ASS out of U and ME.
If you're reading this, you've doubtless heard that before, so I won't repeat it again, but don't forget it.
I was under the (mistaken) impression that our pharmacy had a computerized system for calculating neonatal doses. Type in the weight and the dose, double check it, it goes on the Medication Administration Record (MAR) and is printed on the label for every dose. I double-check the pharmacist's math for doses when I'm giving medications, and I had never found an error before. Not one since they started unit dose quite a few years ago. That changed last night.
The order read Gentamicin 6 mg/kg/dose = 7 mg every 24 hours. It was a small increase in the dose (less than 0.5mg), so the nurse practitioner who wrote the order said that no levels would be needed to monitor the change in dose since the baby had grown that much in the 2 weeks since we'd started antibiotic therapy.
What was printed on the MAR and on the dose of Gentamicin in the refrigerator was Gentamicin 7 mg = 1.66 ml. Concentration = 6 mg/ml. I wasn't giving the dose. It was scheduled for 5 pm the next afternoon, but the pharmacist had made a second, fortuitous error. When the new dose was entered, the time was changed on the MAR to 9am. I was checking the MAR and missed the dosing error on my first pass. I just sent a message to the pharmacy asking them to correct the time and reprinted the MAR to reconcile it again.
I looked at the IV flow sheet for the first new 5pm Gentamicin dose. Not 1.6 or 1.7 ml, but 1.1. It didn't match. I don't know whose guardian angel was bugging me about that. My son says they were having a conference, because something kept me going back to the MAR and the flow sheet until I recognized the error.
1.66 ml = 9.96 mg of Gentamicin. Not the 7 mg that was ordered. That would have been nearly 1.5 times the ordered dose. No levels ordered, because the new dose that was ordered was only slightly higher than the previous dose.
You probably thought I wasn't going to repeat this, but NEVER ASSUME ANYTHING. Always double-check the math and the orders no matter who wrote and/or filled them.