drug disposition & fate of drugs 2 Flashcards
Defines the volume of fluid that must be processed by organs of elimination
volumes of distribution
represents the plasma concentration at the time of drug administration (usually used in intravenous administration).
Cp0
Units of Volume of distribution
Liters or milliliters (describing the whole animal)
Liters/kg or milliliters/kg (normalized to body weight)
equation of volume of distribution
Vd=amount of drug/drug concentration in the plasma
is the sum of all organ clearances
Total body clearance (Clt)
specifically refers to the volume of plasma water cleared of the drug by the liver.
Hepatic clearance or CLEARANCE
The fraction of the volume of distribution cleared per unit time.
Rate constant of elimination
The time for elimination of one half of the total amount in the body.
Elimination Half – Life
refers to the half-life of a drug.
T1/2
half-life of gentamicin
2 to 3 hours in individuals with normal kidney function
is an itital dose of drug given to shorten the time to reach the steady-state concentrations.
loading dose
When a drug is administered by any route OTHER than IV, it is rare that the entire dose is absorbed
Fraction of dose absorbed.
Two drug products are bioequivalent if the nature and extent of therapeutic
and toxic effects are equal following administration
true
Attempt to describe the actual events which control drug absorption, distribution, and elimination
physiologic models
Attempt to accurately predict the time course of drug concentrations in one
(usually blood or plasma) or two (urine as well) body fluids.
Mathematic Models
Bioavailability is a measure of how much of a drug enters the bloodstream.
bioavailability
wo drug products are considered bioequivalent when they have the same therapeutic and toxic effects after administration
bioequivalence
These models are used to understand drug absorption, distribution, and elimination. There are physiologic models that describe real events in the body and mathematical models that predict drug concentrations over time
Pharmacokinetic Models:
drugs can distribute in different body compartments, like the central compartment , peripheral compartment , and deep compartments
Body compartments
2 central compartment
blood
elimination organs
3 peripheral compartments
muscle
subcutaneous tissue
lung
2 deep compartments
fat
kidney
In this practice, _______often simplifies drug distribution to a one-compartment model.
clinical monitoring
Relationship between dose and concentration/effects is linear. If you double the dose, concentrations/effects also double.
dose-independent behavior
