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  2. Effective half-life - Wikipedia

    en.wikipedia.org/wiki/Effective_half-life

    An effective half-life of the drug will involve a decay constant that represents the sum of the biological and physical decay constants, as in the formula: = + With the decay constant it is possible to calculate the effective half-life using the formula:

  3. Biological half-life - Wikipedia

    en.wikipedia.org/wiki/Biological_half-life

    Absorption half-life 1 h, elimination half-life 12 h. Biological half-life (elimination half-life, pharmacological half-life) is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration (C max) to half of C max in the blood plasma.

  4. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, half-life period, dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to half-life in the early 1950s. [1]

  5. Absorption rate constant - Wikipedia

    en.wikipedia.org/wiki/Absorption_rate_constant

    The absorption rate constant K a is a value used in pharmacokinetics to describe the rate at which a drug enters into the system. It is expressed in units of time −1. [1] The K a is related to the absorption half-life (t 1/2a) per the following equation: K a = ln(2) / t 1/2a. [1] K a values can typically only be found in research articles. [2]

  6. Clearance (pharmacology) - Wikipedia

    en.wikipedia.org/wiki/Clearance_(pharmacology)

    In pharmacology, clearance is a pharmacokinetic parameter representing the efficiency of drug elimination. This is the rate of elimination of a substance divided by its concentration. [ 1 ] The parameter also indicates the theoretical volume of plasma from which a substance would be completely removed per unit time.

  7. Elimination (pharmacology) - Wikipedia

    en.wikipedia.org/wiki/Elimination_(pharmacology)

    The plasma half-life or half life of elimination is the time required to eliminate 50% of the absorbed dose of a drug from an organism. Or put another way, the time that it takes for the plasma concentration to fall by half from its maximum levels.

  8. Loading dose - Wikipedia

    en.wikipedia.org/wiki/Loading_dose

    A loading dose is most useful for drugs that are eliminated from the body relatively slowly, i.e. have a long systemic half-life. Such drugs need only a low maintenance dose in order to keep the amount of the drug in the body at the appropriate therapeutic level, but this also means that, without an initial higher dose, it would take a long ...

  9. Plateau principle - Wikipedia

    en.wikipedia.org/wiki/Plateau_Principle

    Most drugs are eliminated from the blood plasma with first-order kinetics. For this reason, when a drug is introduced into the body at a constant rate by intravenous therapy, it approaches a new steady concentration in the blood at a rate defined by its half-life. Similarly, when the intravenous infusion is ended, the drug concentration ...