A drug is eliminated from bloodstream exponentially with half life of 48hours. If patient receives initial dose of 15 milligrams at midnight, how much of drug is in patient's blood at noon the next day?
You're formula Reiny is right, but your numbers are incorrect. You should only use 12 hours not 36 as the patient received the medication at midnight and going to noon is only 12 hours. Therefore the answer is 12.61mg left in the bloodstream.
The half-life of a drug in the bloodstream is 9 hours. What fraction of the original drug dose remains in 12 hours?
To determine how much of the drug is in the patient's blood at noon the next day, we need to calculate the number of half-lives that have elapsed and use that information to calculate the remaining amount of the drug.
Given that the half-life of the drug is 48 hours, we know that after each 48-hour period, the amount of drug in the bloodstream is halved.
Let's break down the timeframe from when the initial dose is administered at midnight to noon the next day:
1. From midnight to noon the next day is a total of 12 hours.
2. Since the half-life of the drug is 48 hours, we need to determine how many half-lives have occurred within this 12-hour period.
To calculate the number of half-lives that have occurred, we can divide the elapsed time by the half-life:
Number of half-lives = (Elapsed time) / (Half-life)
Number of half-lives = 12 hours / 48 hours = 0.25 half-lives
Now, let's calculate the remaining amount of the drug:
Remaining amount = Initial dose * (1/2)^(Number of half-lives)
Remaining amount = 15 mg * (1/2)^(0.25) ≈ 15 mg * 0.8409 ≈ 12.61 mg
Therefore, at noon the next day, approximately 12.61 milligrams of the drug will remain in the patient's bloodstream.
so the time from midnight to noon of next day
= 36 hours
( from midnight to noon of the same day = 12 hours
so to noon of next day = 12+24 = 36 hrs )
amount in bloodstream
= 15 (1/2)^(36/48) = 8.92 mg