Question

A certain drug has a half-life in the body of 4.0h. What should the interval between doses be, if the concentration of drug in the body should not fall below 15.% of its initial concentration? Round your answer to 2 significant digits.

Answer 1

Step-by-step explanation:

half life = 4 h

initial concentration = 100

final concentration = 15

Time = t

No of half life x = t / 4

15 = 100 x ( 1/2 )ˣ

.15 = ( 1/2 )ˣ

ln .15 = - x ln2

x = - ln .15 / ln 2

= 1.897 / .693

x = 2.737

x = t / 4

t = 2.737 x 4 = 11 h approx .