anatomy
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While receiving mechanical ventilation, a 57-year-old man contracts pneumonia caused by Pseudomonas aeruginosa. The patient is given antibiotic therapy with ceftazidime and gentamicin. Assuming the half-life of gentamicin is 3 hours in this particular patient, what percentage of the initial dose will most likely remain in his body 6 hours later?
A. 12.5
B. 25
C. 33
D. 50
E. 75
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| zahra97
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B.25%
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| anatomy
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can u pls tell me how?pls explain it.
i know u r right.
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| kmp
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ya the answer is 25%.
half life is 3 hrs so the question is asking after 6 hrs (so it has 2 half lifes).
so 100%of drug becomes 50% in the first half life (3 hrs) and 50% becomes 25% in the 2 nd half life (3 hrs).
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| anatomy
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kmp i didn''t understand.can u pls explain it in simple way.
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| vermdocamit
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1200 AM--Start--- 100%
300AM --3hrs later--- 50 % of 100 = 50
600AM---3+3 hrs --- 50%of 50 = 25
:lol:
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| anatomy
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thanx alot for explain me.we can also explain this in this way too.
the half-life of a medication is the time required for one-half the total amount of the medication to be excreted from the body. For any given first-order elimination process, 50% of the initial amount of drug is eliminated at the end of the first half-life, 50% of the remaining amount of drug in the body is eliminated at the end of the second half-life, and so on. Therefore, after 3 hours 50% of the gentamicin will be remaining in the body. After another 3 hours (6 hours total), 50% of the remaining 50% will be eliminated. In other words, after 6 hours, 75% of the gentamicin will be eliminated, and 25% of the initial dose will remain.
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