If the directions on a RX state to take Metformin 1g q.d. for 90 days and the pharmacy has 500mg tablets, how many tablets are needed?

To determine how many tablets of Metformin are needed for a 90-day supply when the prescription states to take 1g (or 1000mg) once daily, it’s essential to start with the total dosage required over the entire period.

First, we calculate the total amount of medication needed over the 90 days:

1g per day for 90 days equals:

1000mg/day * 90 days = 90,000mg.

Since each tablet contains 500mg, we can figure out how many tablets are necessary by dividing the total amount needed by the strength of each tablet:

90,000mg ÷ 500mg/tablet = 180 tablets.

Therefore, the calculation confirms that a total of 180 tablets is necessary to fulfill the prescribed dosage over the 90-day period. This leads to the conclusion that the correct answer is indeed that 180 tablets are required.