After reconstitution with 1.5 ml diluent, a 500 mg vial of ceftazidime injection yeilds an approximate volume of 1.8 ml.Each ml contains approximately 280 mg.If 500 mg IM are ordered, how many ml should be administered?

I may have missed something here but if the vial contained 500 mg initially, it appears to me that the entire 1.8 mL should be administered and that will be exactly 500 mg. I don't know the meaning of IM. Perhaps that makes a difference.