[TD]Please help.... I have asked and asked and cannot get a clear answer on how you "choose" the correct range of diluent in these kinds of questions. I assumed you pick the range closest to the order which would be 250,000, but the answer key says the correct choice is 200,000. I have to retake the math exam tomorrow to get into clinical and I am struggling with this type of question.... I am having the same problem with insulin and heprin... I cannot understand how to pick the right range of concentration for each question.... I am not having a problem with the DA math equations but with picking ranges... Please help... is there a RULE ?
Example
The order is to give 300,000 units of Penicillin G Potassium IM. A concentration of 200,000 units/ml should be used. The medication on hand is in a 1,000,000 unit vial. How many mL will you give?
[TABLE]
[TR]
[TD]Here are typical instructions for reconstitution of medication
If the bottle tells you that adding 4.6cc to it makes a total of 5cc with a concentration of 200K units/cc, then that is true for that drug and that's what you work with.
Another drug might tell you to add 3.9cc for a total of 6cc with a concentration of 2mg/cc; then you believe that and proceed accordingly.
Another drug might say to add 9.5cc for a total of 10cc with a concentration of 600mg/cc; then you believe that.
I think what I hear you struggling with is that you are looking for a hard-and-fast rule about how much diluent to add to any vial to get a volume that is safe to administer via a given route. There is no such rule. What this test question is asking is whether you know what's a safe volume to give IM (2cc is about right for a max in an adult thigh). That's a separate question than how much diluent to mix the drug with; that instruction is given separately on the label or in the set-up for the question. In this case, you get 200,000 units per cc and the prescribed dose is 300,000 units, so the dose will be 1.5cc and do you know whether that's safe to give in one IM or not? That's the question.
nurseprnRN, BSN, RN
1 Article; 5,116 Posts
If the bottle tells you that adding 4.6cc to it makes a total of 5cc with a concentration of 200K units/cc, then that is true for that drug and that's what you work with.
Another drug might tell you to add 3.9cc for a total of 6cc with a concentration of 2mg/cc; then you believe that and proceed accordingly.
Another drug might say to add 9.5cc for a total of 10cc with a concentration of 600mg/cc; then you believe that.
I think what I hear you struggling with is that you are looking for a hard-and-fast rule about how much diluent to add to any vial to get a volume that is safe to administer via a given route. There is no such rule. What this test question is asking is whether you know what's a safe volume to give IM (2cc is about right for a max in an adult thigh). That's a separate question than how much diluent to mix the drug with; that instruction is given separately on the label or in the set-up for the question. In this case, you get 200,000 units per cc and the prescribed dose is 300,000 units, so the dose will be 1.5cc and do you know whether that's safe to give in one IM or not? That's the question.
Hope you did well on your test today!