78. A patient needs 1.5 million units of penicillin G benzathine in a single IM injection. Supplied in 2 mL vials containing 1.2 million units per vial. Volume to draw?
Answer: D
The volume to draw is 2.5 mL.
To administer 1.5 million units of penicillin G benzathine, the patient will require a total volume of 2.5 mL, as each vial contains 1.2 million units in 2 mL. This means that to reach the desired dosage, more than one vial will be needed.
A) 0.6
Drawing 0.6 mL would yield only 360,000 units of penicillin G benzathine (0.6 mL x 600,000 units/mL), which is significantly less than the required 1.5 million units. Therefore, this option is incorrect.
B) 0.8
If 0.8 mL is drawn, it would provide 480,000 units of penicillin G benzathine (0.8 mL x 600,000 units/mL), still falling short of the 1.5 million units required. This option is also incorrect.
C) 1.3
Drawing 1.3 mL would result in 780,000 units of penicillin G benzathine (1.3 mL x 600,000 units/mL), which is insufficient to meet the patient's needs of 1.5 million units. Hence, this option is incorrect.
D) 2.5
Drawing 2.5 mL is the correct choice as it would provide 1.5 million units of penicillin G benzathine (2.5 mL x 600,000 units/mL). This volume meets the patient's requirement perfectly, making this the correct answer.
Conclusion
The correct answer is 2.5 mL, as this volume delivers the precise dosage of 1.5 million units required by the patient. All other options result in insufficient dosages, failing to meet the therapeutic needs of the patient. Thus, option D is the only viable choice.