Final answer:
To calculate how much of the drug is in the body right after the last dose, we need to consider the half-life of the drug and the dosing interval. After 10 days, approximately 0.11 mg of the drug is still in the body.
Step-by-step explanation:
To calculate how much of the drug is in the body right after the last dose, we need to consider the half-life of the drug and the dosing interval. The half-life is the time it takes for the concentration of the drug in the body to be reduced by half. In this case, the drug has a half-life of 12 hours. After 12 hours, about 3% of the dose is still in the body, so we can assume that the concentration of the drug decreases by 97% every 12 hours.
Let's calculate the remaining dose after 10 days, or 240 hours:
Remaining dose = Initial dose * (97%)^(total hours / half-life)
Initial dose = 225 mg
Total hours = 240 hours
Half-life = 12 hours
Remaining dose = 225 mg * (0.97)^(240 / 12)
Remaining dose ≈ 225 mg * 0.00048828125 ≈ 0.10986328125 mg
Therefore, right after the last dose, approximately 0.11 mg of the drug is still in the body.