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# kinetic parameters

### Pharmacokinetics

Term | Definition |
---|---|

rate of reaction | the rate of a chemical reaction is the velocity with which the reaction occurs |

if amount of drug A decreases with time the rate of reaction is | negative |

if amount of drug B increases with time the rate of reaction is | positive |

order of reaction | the way in which the concentration of reactants influences the rate of the reaction |

zero-order reaction | linear C = -k0*t + C0 amount of drug eliminated over time is the same |

significance of zero-order reaction | important for saturable reactions |

first order reaction | if the amount of drug A is decreasing at a rate that is proportional to the amount of drug A remaining log C = -kT/2.303 + log C0 |

significance of first order reaction | most kinetic processes in the body like drug transport, clearance and metabolism are first order |

t/f in zero and first order reactions rate and rate constants are the same | false- first order reactions rate and rate constants are different |

what are the units for zero and first order reactions K (rate constant) | zero- mass/time first- time^-1 |

t/f zero order reactions are dependent on mass | false- rate is independent on mass |

t/f first order reactions are dependent on mass | true |

t/f zero order reactions rates are constant for entire reaction | true |

t/f first order reactions rates change as well as the rate constant | false. the rate constant is constant, the rate changes |

volume of distribution | fluid volume that would be required to contain all the drug in the body at the same concentration measured in the blood or plasm- apparent volume of fluid in which the drug is dissolved |

significance of volume of distribution Vd | Vd > 100% of total body weight indicated drug is concentrated in extravascular tissues- Cplasma is low; low Vd indicates drug is concentrated in vascular compartment, Vd is constant for each drug except under certain pathological conditions |

clearance | volume of plasma fluid that is cleared of drug per unit time |

clearance is expressed as | expressed as mass or volume or fraction of drug eliminated per unit time |

extraction ratio | measure of an organ's ability to remove the drug |

organs that are highly efficient at eliminated drugs have an extraction ratio of | one |

clearance from any organ is determined by two factors | blood flow (Q) and extraction ratio (E) |

significance of clearance | index of the capacity for drug removal by the body organs, most important concept to consider when designing a rational regimen for long-term drug administration |

clearance depends on | conditions that alter blood flow to liver or kidney, hepatic and renal diseases that alter elimination |

elimination rate constant | represents the fraction of drug removed per unit of time |

most drugs are eliminated from plasma by which order | first order |

half life | time required for the amount or concentration of a drug in plasma to decrease by one half |

A drug's half life is related to | its duration of action, indicated when the next is to be given |

zero order half life | proportional to initial amount or concentration of drug and inversely proportional to zero-order rate constant, not used clinically |

first order half life | constant and is independent of initial amount or concentration of drug but inversely proportional to rate constant, clinical practice |

area under the curve | represents the area under the plasma concentration vs time- reflects the total amount of active drug that reaches systemic circulation |