Question

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?

Answer 1

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

Answer 2

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.

Answer 3

The​ half-life of a drug in the bloodstream is 9 hours. What fraction of the original drug dose remains in 12 ​hours?