What does half-life mean?

Half-life, in radioactivity, the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive

What is a drug half-life mean?

The half-life of a drug is the time it takes for the amount of a drugs active substance in your body to reduce by half. This depends on how the body processes and gets rid of the drug. It can vary from a few hours to a few days, or sometimes weeks.

How many half-lives does it take to clear a drug from the body?

Even further, 94 to 97% of a drug will have been eliminated after 4 to 5 half-lives. Thus, it follows that after 4 to 5 half-lives, the plasma concentrations of a given drug will be below a clinically relevant concentration and thus will be considered eliminated.

What does it mean if a drug has a half-life of 4 hours?

1 This means if you take a dose of 400 milligrams (mg) of ibuprofen at noon, half of the dose (200 mg) will have been eliminated from your bloodstream by 2 p.m. By 4 p.m., another 100 mg will have been eliminated, and so forth.

What is half-life in psychology?

The half-life of knowledge is an interesting and important concept. Half-life of knowledge refers to the number of years that it would take for half of the information or knowledge available in a field of study to become defunct or superseded by new information.