Certified Medical Assistant (CMA AAMA)PharmacologyMedium
A physician orders amoxicillin 250 mg PO for a child. The suspension on hand is labeled 125 mg per 5 mL. How many mL should the medical assistant administer?
- A5 mL
- B12.5 mL
- C10 mL
- D2.5 mL
Show answer & explanationAnswer & explanation
Correct answer: C. 10 mL
Using the formula (Desired dose ÷ Available dose) × Volume: (250 mg ÷ 125 mg) × 5 mL = 2 × 5 mL = 10 mL. The medical assistant should administer 10 mL of the suspension.
Why the other options are wrong
- A. This equals the concentration volume alone, not the calculated dose.
- B. This would result from an incorrect ratio calculation.
- D. This would be correct if the order were 125 mg, not 250 mg.
Dosage Calculation - Liquid Medications
Formula: (Desired dose ÷ Have dose) × Volume = Amount to give.
- Always convert units before calculating
- Double-check by verifying the ratio makes sense
- Common error: transposing numerator and denominator
Memory trick: 'Desired over Have, times Volume, gives you the answer to have'