clar697
Forum Guru
Topics: 190
Posts: 199
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A 13-year-old girl is brought to the emergency department by her father after he found her in a semicomatose state with an empty bottle of antihistamine beside her bed. Plasma diphenhydramine concentrations measured hourly for 6 hours are shown.
Time plasma drug concentration (ng/mL)
1:00PM 240
2:00PM 202
3:00PM 170
4:00PM 143
5:00PM 120
6:00PM 101
Approximately how long after the first measurement (in hours) will it take for the patient’s plasma concentration to drop below 10 ng/mL?
A) 10
B) 12
C) 16
D) 20
E) 24
F) 30
G) 38
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| Gourdon
Topics: 14
Posts: 82
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A
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| jess_k
Forum Newbie
Topics: 0
Posts: 2
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D
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| sukkyman
Forum Newbie
Topics: 0
Posts: 2
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Why A? Why B?
What is the ans?
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| aml
Forum Senior
Topics: 5
Posts: 129
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I think most drugs follow 1 st order kinetics for which t 1/2 is constant.
So time taken for plasma drug conc. to fall from 240 to 120ng/ml is 4 hrs.
Therefore 240-->120-->60-->30-->15-->7.5.
So 5 elimination half-lives, i.e. 5 X 4 = 20 hrs approx.
D probably is the answer
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