Half-life

Definition

Half-life is the time required for the concentration of a drug in the bloodstream to reduce by half. It helps determine dosing intervals and duration of drug effects.

5 Must Know Facts For Your Next Test

1. Half-life determines how frequently a drug needs to be administered.
2. A longer half-life means the drug stays longer in the system, requiring less frequent dosing.
3. Shorter half-life drugs may need multiple doses per day to maintain therapeutic levels.
4. Knowledge of a drug's half-life is crucial for avoiding toxicity or subtherapeutic dosing.
5. Factors such as age, liver function, and kidney function can affect a drug's half-life.

Review Questions

• Why is understanding a drug's half-life important for determining dosing intervals?
• How does a longer half-life influence the frequency of drug administration?
• What factors can alter the half-life of a medication?

Related terms

Pharmacokinetics:

The study of how drugs move through the body.

Therapeutic Range: The concentration range in which a drug exerts its clinical effect without causing toxicity.

Bioavailability:

The proportion of a drug that enters circulation when introduced into the body and can have an active effect.