Oral Absorption Flashcards
When is a zero-order absorption model used?
It occurs when either the drug is absorbed by a saturable process or a zero-order controlled release delivery system is used.
What is the equation to find the concentration of drug in plasma following a single oral dose?
Cp = (FkaD0) / (Vd(ka-k)) (e^-kt - e^-kat)
What is the equation for tmax?
tmax = ln(ka/k)/(ka-k)
What is disposition rate limiting?
absorption half-life is much shorter than elimination half-life.
What is absorption rate limiting?
Absorption half-life is much longer than elimination half-life.
What is lag time?
time delay prior to the start of first-order drug absorption.
What may lag time be attributed to?
Slow tablet disintegration Slow and/or pooro drug dissolution from the dosage form Incomplete wetting of drug particles. Poor formulation A delayed release formulation
Why is absorption rate constants significant?
Designing multiple-dosage regimens.
Prediction of peak and trough plasma drug concentrations.
Bioequivalence studies - comparing rates of absorption from chemically equivalent products.
The peak time (Tmax) can be used to?
Determine the comparative bioavailability and/or bioequivalence.
Determine the preferred route of drug administration and the desired dosage from for the patient.
Assess the onset of action.
The pake plasma concentration (Cmax) can be used to?
Determine the comparative bioavailability and/or bioequivalence.
Correlate with the pharmacological effect.
Oral administration usually refers to _______ order absorption and _____ order elimination.
First and first
Plasma drug concentration any time after oral administration can be calculated provided basic pharmacokinetic parameters. T/F
True
The time at which peak plasma concentration is based on what?
The rate constants of absorption and elimination.
Bioavailability can be estimated given?
basic parameters.
