clinical trials - saonew

[ArchivalUser]

A new antifungal medication is being tested in Phase I clinical trials. Examination of the pharmacokinetic properties of the drug reveals that the half-life of the drug is 6 hours. If a continuous intravenous infusion of this drug were started on a research subject, how long would it take to reach 75% of steady state?



(A) 3 hours

(B) 6 hours

© 9 hours

(D) 12 hours

(E) 18 hours

(F) 24 hours

[ArchivalUser]

d???

[ArchivalUser]

(D) 12 hours

[ArchivalUser]

dd

[ArchivalUser]

dd

[ArchivalUser]

18h ?

[ArchivalUser]

dd

[ArchivalUser]

dd

[ArchivalUser]

The correct answer is D. The rule of thumb is that the plasma concentration will reach 50% in one half-life, 75% in two half-lives, 87.5% in three half-lives, etc., so that the difference between the current drug level and 100% halves with each half-life. In this instance, it takes two half-lives to reach 75%. The half-live of this drug is 6 hours, so two half-lives is 12 hours.