A physician orders Celestone IM for contact dermatitis. The order is for 2 mL. The vial on hand contains Celestone at 3 mg/mL. How many milliliters will be administered?

A physician orders Celestone IM for contact dermatitis. The order is for 2 mL. The vial on hand contains Celestone at 3 mg/mL. How many milliliters will be administered?

• A. 1 mL
• B. 2 mL
• C. 0.5 mL
• D. 3 mL

Answer: (B)

When a dosage is written in milliliters, you administer that exact volume—the concentration only tells you how much drug is in that volume, not how much to give. Here, the order is for 2 mL, so you would administer 2 mL. The vial is 3 mg/mL, so this 2 mL dose delivers 2 × 3 = 6 mg of Celestone. If the order had been in milligrams, you’d use the concentration to convert mg to mL (mg ÷ mg/mL) to find the correct volume.

When a dosage is written in milliliters, you administer that exact volume—the concentration only tells you how much drug is in that volume, not how much to give. Here, the order is for 2 mL, so you would administer 2 mL. The vial is 3 mg/mL, so this 2 mL dose delivers 2 × 3 = 6 mg of Celestone. If the order had been in milligrams, you’d use the concentration to convert mg to mL (mg ÷ mg/mL) to find the correct volume.