The antibiotic ampicillin sodium has 2.9 mEq Na+ per gram. If you prepare an IV with 2 grams of ampicillin in 100 ml NaCl solution, how many milliequivalents of sodium are in the IV?
(A) mEq Na+ in 2 g ampicillin sodium
(B) mEq Na+ in 100 mL 0.9% NaCl
(C) total mEq Na+
My answer:
(A) 5.8 mEq
(B) 2.61 mEq (but the answer key says that it is 15.5 mEq)
(C) 8.41 mEq (answer key says 21.3 mEq)
To calculate the number of milliequivalents (mEq) of sodium in the IV solution, we need to consider the sodium content in both the ampicillin sodium and the NaCl solution.
(A) mEq Na+ in 2 g ampicillin sodium:
Given that ampicillin sodium has 2.9 mEq Na+ per gram, we can calculate the amount of sodium in 2 grams of ampicillin sodium as follows:
2 grams × 2.9 mEq/g = 5.8 mEq
Therefore, the mEq of sodium in 2 grams of ampicillin sodium is 5.8 mEq.
(B) mEq Na+ in 100 mL 0.9% NaCl:
To determine the mEq of sodium in the 100 mL 0.9% NaCl solution, we need to know the concentration of NaCl in the solution. A 0.9% NaCl solution means that there is 0.9 grams of NaCl in 100 mL of solution. We can convert this weight to mEq using the atomic weight of sodium and chloride.
The atomic weight of sodium (Na) is approximately 23 and the atomic weight of chloride (Cl) is approximately 35.5.
To calculate the mEq of sodium in 0.9 grams of NaCl:
0.9 grams NaCl × (1 mole NaCl / 58.5 grams NaCl) × (1 mole Na+ / 1 mole NaCl) × (1,000 mEq / 1 mole Na+) = 15.4 mEq
Therefore, there are approximately 15.4 mEq of sodium in 100 mL of 0.9% NaCl solution, not 2.61 mEq as you mentioned.
(C) Total mEq Na+:
To calculate the total mEq of sodium in the IV, we need to add the mEq of sodium from the ampicillin sodium (A) to the mEq of sodium from the NaCl solution (B):
Total mEq Na+ = mEq Na+ in 2 g ampicillin sodium + mEq Na+ in 100 mL 0.9% NaCl
Total mEq Na+ = 5.8 mEq + 15.4 mEq
Total mEq Na+ = 21.2 mEq
Therefore, the correct total mEq of sodium in the IV should be 21.2 mEq, not 8.41 mEq as you mentioned.