Intro to PK Flashcards
What makes something a poison?
The dose
What is drug therapy?
Planned action that involves risk of unwanted adverse effects
How is a drug dose chosen?
Based on its ability to achieve and maintain therapeutic (target) concentrations producing minimal adverse effects in the body
Define appropriate dosage regimen
- Therapeutic window between MTC and MEC
- To achieve and maintain safe and effective therapy
What are components of appropriate dosage regimen?
A: Right drug
B: Dose of a drug
C: Dosage form
D: Route of admin
E: Dosing interval/frequency
F: Duration of therapy
What information do we need to design appropriate dosage regimen?
- Therapeutic range of the drug
- PK parameters of the drug
What is a therapeutic range of a drug?
- Minimum (Cmin) and maximum (Cmax) plasma drug concentration values
Where are therapeutic range values found?
- Between MEC and MTC
- Estimated average plasma concentration (Cavg)/Css
What are the PK parameter of a drug?
Vd, CL, Half-life
How does Vd effect loading dose?
It relates plasma concentration to the amount of drug in the body
What is LD?
A large initial dose given to achieve therapeutic drug levels from the beginning
How is Cl used to determine maintenance dose (dosing rate)?
It measures the rate of drug elimination that needs to be replaced to maintain therapeutic concentration
What is another name for Cmax
MTC
What is another name for Cmin?
MEC
What is MD?
Given at fixed intervals to keep drug concentrations within the therapeutic concentration range
Why is half-life used for dosage regimen design?
It affects the time to reach Css and determines the shape of the plasma concentration-time courses
What are all the PK parameters used to estimate plasma concentration-time profiles?
- Vd
- Cl
- T1/2
- Cmax
- Cmin
- Cavg/Css (therapeutic range)
- Tmax
- AUC
- F
What are parameters?
Observable quantities that remain constant for every state of a system
What is the purpose for PK?
To study ADME processes of drugs in the body to examine the time course of drug concentrations in mainly plasma, and also in urine and bile
What are the methods used to analyze plasma drug concentration-time profiles?
- Non-compartmental analysis techniques (NCA)
- Compartmental model fitting methods
What is another name for NCA?
Model-independent approaches
What is are the approaches of NCAs?
- Applies the trapezoidal rule for measuring AUC
- Estimates Cmax using tmax directly from the data and Cl, k, t1/2, and Vd driven equations
How does the compartmental model fitting methods help determine PK parameters?
- Provide a continuous description of drug concentration
- Consider the body as a finite number of interconnected, well-mixed, homogenous compartments
- Mathematical PK models are developed using nonlinear regression methods to estimate PK parameters
- drug concentrations over a time range are predicted using the developed PK model to estimate Cmax , tmax , Cavg / Css , AUC, F
What are the PK approaches of designing dosage regimens?
- Individualized dosage regimen (Patient-specific values)
- Dosage regimen based on population values
- Dosage regimen based on partial PK parameters (Bayesian approach)
