What percentage of a novel anti-obesity drug will be eliminated 20 hours after ingestion, given its half-life is 4 hours?

To determine the percentage of a novel anti-obesity drug that will be eliminated 20 hours after ingestion, knowing its half-life is 4 hours is essential.

The concept of half-life refers to the time it takes for half of the drug to be eliminated from the body. If the half-life is 4 hours, this means that after 4 hours, 50% of the drug remains.

To calculate how many half-lives fit into 20 hours, divide 20 by the half-life of 4 hours:

20 hours ÷ 4 hours/half-life = 5 half-lives.

Now we can calculate how much of the drug remains after each half-life:

• After the first half-life (4 hours): 50% remains.

• After the second half-life (8 hours): 50% of 50% = 25% remains.

• After the third half-life (12 hours): 50% of 25% = 12.5% remains.

• After the fourth half-life (16 hours): 50% of 12.5% = 6.25% remains.

• After the fifth half-life (20 hours): 50% of 6.25% =