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How Long It Takes For The Drug To Be Effectively Eliminated From The Body After Administration Of A Single Dose?

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Posted on Sat, 4 Aug 2012
Question: I have a question....

If a drug has a half life of 6 hours, how long will it take for the drug to be effectively eliminated from the body after administration of a single dose?
doctor
Answered by Dr. Kiran Kumar (8 hours later)
Dear XXXXXX

Thanks for writing in.

It usually takes Five Half Lives for a drug to be cleared from the body.

Eliminatin half life of the drug however is a dependent variable.
It depends on two factors.

1. Clearance. Most drugs are excreted by kidneys and therefore a normal kidney function is required to eliminate the drugs in five half lives. If there is derangement of kidney functions, the drug can be in the body for longer periods.

2. Volume of distribution. Some drugs are removed from the plasma or blod and distributed to other body fluids. From there, they are gradually liberated into the blood again. Here again, the elimination half life becomes prolonged.

If a steady state has been reached, a drug with half life of 6 hours would take 30 ie. 6 x 5, hours to be elimiated.

Hope this answers your query.

Do get back if you have any further concens.

Sincerely,

Dr Kiran
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Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Kiran Kumar

Internal Medicine Specialist

Practicing since :2007

Answered : 362 Questions

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How Long It Takes For The Drug To Be Effectively Eliminated From The Body After Administration Of A Single Dose?

Dear XXXXXX

Thanks for writing in.

It usually takes Five Half Lives for a drug to be cleared from the body.

Eliminatin half life of the drug however is a dependent variable.
It depends on two factors.

1. Clearance. Most drugs are excreted by kidneys and therefore a normal kidney function is required to eliminate the drugs in five half lives. If there is derangement of kidney functions, the drug can be in the body for longer periods.

2. Volume of distribution. Some drugs are removed from the plasma or blod and distributed to other body fluids. From there, they are gradually liberated into the blood again. Here again, the elimination half life becomes prolonged.

If a steady state has been reached, a drug with half life of 6 hours would take 30 ie. 6 x 5, hours to be elimiated.

Hope this answers your query.

Do get back if you have any further concens.

Sincerely,

Dr Kiran