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A new investigational drug is undergoing Phase I clinical trials. The half-life of this drug is 9 hours. A healthy volunteer has an adverse reaction and the drug is immediately discontinued. How long will it take until the plasma drug level is approximately 6% of the steady state level?
A. 9 hours
B. 18 hours
C. 27 hours
D. 36 hours
E. 45 hours
F. 54 hours
 

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can some1 plz explain this,
If the 1/2 life =9hrs,it means that it will take 9hrs for 1/2 of the drug to disintegrate making only 50% available,another 9hrs to breakdown 50% of the 50,making it only 25% available,another 9hrs to break 1/2 of that down to 12.5% and then another 9hrs to break it to 6.something %.So,it takes 9hrs x 4 (36hrs) to get 6% of the drug in the system....hope that helps.Pray for me to pass my step 1 and goodluck :)
 
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