PharmacoKINETICS Flashcards
Define PharmacoKINTETICS…
What the animal does to the drug
Rate=
How fast the mass (dose) of a RX changes per unit time (mg/min)
Extent=
How much the mass (dose) of a RX changes in total
PharmacoKINETICS allows us to evaluate the rate and extend of…..
Absorption
Distribution
Elimination
Non-compartmental (stochastic) models
Most common in vet med.
statistical moments – like the Mean Residence Time (which basically represents the average amount of time any given molecule of drug stays in the body).
________: This system estimates pharmacokinetics by looking at populations
Population pharmacokinetics
_______: This uses pharmacokinetic data in multiple species to try to predict the behavior of a drug in a species for which this information is unknown.
Allometric scaling / Interspecies Extrapolation
Non-linear models
Used when drugs follow zero-order kinetics
the fraction of the given dose which finds its way into systemic circulation. This is calculated from the area under the plasma concentration-time curve (AUC)
Bioavailability (F)
Comparing 2 formulations of the same RX. Trade name VS generic
Bioequivalence
CMAX (maximum plasma concentration) and TMAX (the time at which CMAX is reached
Bioequivalence
Half-life (t1/2):
time required for the drug concentration to decrease by one-half (or 50%).
amount of drug eliminated per unit time is fixed, regardless of plasma concentration. There are relatively few drugs used in veterinary medicine that normally follow this.
Zero-order elimination/kinetics
The proportion of drug eliminated per unit time is fixed. The vast majority (maybe 95%) of drugs used in veterinary medicine will follow this type of kinetics at therapeutic doses, and for these drugs the compartment or stochastic models work well for predicting pharmacokinetics
First-order elimination/kinetics
Drugs that normally undergo first-order elimination may convert to zero-order if a _______ dose is given and elimination systems are saturated.
Massive/over
When saturation occurs the clearance (CLB) decreases and the half-life (t1/2) increases which can lead to…
RX accumulations AND potential toxicity