A medication order calls for 250 mg of metformin. On hand you have 500 mg tablets. How many tablets are required?

A medication order calls for 250 mg of metformin. On hand you have 500 mg tablets. How many tablets are required?

• A. 1 tab
• B. 1/4 tab
• C. 2 tabs
• D. 1/2 tab

Answer: (D)

Calculating how many tablets to give comes from matching the desired dose to the strength of each tablet. Here, you want 250 mg, and each tablet is 500 mg. Do the division: 250 mg ÷ 500 mg per tablet = 0.5. That means half a tablet is needed to reach 250 mg. In practice, this is feasible only if the tablet can be safely split (usually it must be scored). If the tablet isn’t designed to be split, a different strength or formulation would be required to deliver exactly 250 mg. Quick check: giving a whole tablet would deliver 500 mg, which is double the prescribed dose, while a quarter tablet would be 125 mg, which is short of the target.

Calculating how many tablets to give comes from matching the desired dose to the strength of each tablet. Here, you want 250 mg, and each tablet is 500 mg. Do the division: 250 mg ÷ 500 mg per tablet = 0.5. That means half a tablet is needed to reach 250 mg.

In practice, this is feasible only if the tablet can be safely split (usually it must be scored). If the tablet isn’t designed to be split, a different strength or formulation would be required to deliver exactly 250 mg. Quick check: giving a whole tablet would deliver 500 mg, which is double the prescribed dose, while a quarter tablet would be 125 mg, which is short of the target.