Dosage Calculation Question

[NewBeee]

hello everyone,

i am really having trouble with a certain category of reconstitution questions. this type of question always asks for you to choose the concentration to reconstitute. could someone explain why they are choosing this concentration??? thanks! p.s. i'm a newbie nursing student if that explains anything =)

order: penicillin g sodium 500,000 units im q.12h

reconstitue with ________ml diluent for a concentration of ________units/ml and give ______ml.

select: ______ syringe

instructions on bottle say: preparation of solution: add 23 ml, 18 ml, 8 ml, or 3 ml diluent to provide 200,000 u, 250,000 u, 500,000 u, or 1,000,000 u per ml, respectively.

answer: reconstitue with ___3___ml diluent for a concentration of _1,000,000___units/ml and give __0.5__ml.

select: 3ml syringe

***now why wouldn't you just reconstitute with 23 ml for a concentration of 200,000 units and give a dosage of 2.5 ml in a 3ml syringe???? won't this be less irritating to the muscle? i have been confused about this whole problem this entire weekend. :confused:

[loricatus]

Take a look at 1D. You would be giving the maximum recommended amount and would risk damage more with a higher mL. It is better to compromise between the minimum and maximum allowable amounts to acheive a safety balance.

http://www.brooksidepress.org/Products/Administer_IM_SQ_and_ID_Injections/lesson_2_Section_1.htm#2-3.%20PROCEDURE%20FOR%20ADMINISTERING%20AN%20INTRAMUSCULAR%20INJECTION

However, I would think that 1mL would be the appropriate amount & the dilution needed to get the proper units supports that answer better than the 1/2 mL (IMO).

[locolorenzo22, BSN, RN]

my thought is that when giving a IM injection, you want to give the smallest amount possible to avoid as much muscle irritation as possible. Personally, I will give 1mLs in the deltoid(although that is the max)....but I prefer to give almost all IMs in the vastus lateralus....seems to work better that way.