Answer is: it takes 1,448 billion years.

The correct option is (A) 3%.

What is the half-life of a radioisotope if a 40 g sample becomes 10 g after 20 minutes? 10 minutes.

What is a drug’s half-life? The half-life of a drug is the time it takes for the amount of a drug’s active substance in your body to reduce by half. This depends on how the body processes and gets rid of the drug.

Let’s talk about three of the main ones:

1. Dosing interval. The dosing interval affects steady-state concentration in a proportional way.
2. Dose. In the same way, higher doses will increase the Css values, and lower doses will decrease them.
3. Drug clearance.

Clearance is equal to the rate at which a drug is removed from plasma(mg/min) divided by the concentration of that drug in the plasma (mg/mL).

To find the actual amount of drug eliminated each minute, one must know the average concentration of drug in the arterial blood to the organ of elimination during that minute. One then multiplies that concentration times the CL to find the amount of drug eliminated during that minute.

Clearance is variable in zero-order kinetics because a constant amount of the drug is eliminated per unit time, but it is constant in first-order kinetics, because the amount of drug eliminated per unit time changes with the concentration of drug in the blood.

High extraction ratio. These drugs are rapidly and extensively cleared from the blood by the liver (e.g. in a single pass). Their clearance depends primarily on hepatic blood flow, and binding to blood components is not an obstacle for extraction; the extraction is said to be non-restrictive or blood flow dependent.