T2 - 2-COM Model Flashcards
What is a compartment?
An imaginary unit in which different tissues with similar rates of drug are grouped together
How is a compartment a homogenous unit?
- Drug concentration is uniform throughout at all times
- Drug concentration in a compartment is continuously changing with time
- Pharmacokinetic models
What are pharmacokinetic models?
Differential equations used to describe the rate of change in drug concentration
What comprises a compartment?
- Amount of drug distributed in a volume to give drug concentration in the compartment
- A drug in blood stream -> distributes to the tissues in the body
- A drug in blood stream -> distributes to the tissues in the body
Why are pharmacokinetic models mathematically constructed?
- Describe the rate of movement/transfer of drug between compartments
- Explain the relationship of drug concentration with time after drug dose
- Predict the time-course of drugs in the body to allow us to maintain drug concentration in the therapeutic range to monitor
- Summarize data
How are clinically observed plasma concentration-time profiles described?
One, two, or three compartment pharmacokinetic models
Describe the schematics of an one compartment model?
Describe the schematics of a two compartment model?
Describe the schematics of a three compartment model?
What is the process of a drug moving from central to peripheral compartment?
Distribution = Distribution Cl
What is the process of a drug moving from peripheral to central compartment?
Redistribution = Clearance
What are the most clinically used compartments?
one or two due to its simplicity
What are the assumptions of the 2 com model?
- At 𝑡=0, no drug is present in the peripheral compartment.
- Each compartment is individually well-stirred.
- Distribution and elimination are first-order.
- Change in the rate of drug concentration over time is represented by: (𝑑𝐶/𝑑𝑡) = - k * C
Describe the differences between 1 and 2 com models?
How can we determine the rate of a 2 Com model?
- 𝐑𝐚𝐭𝐞 𝐨𝐟 𝐜𝐡𝐚𝐧𝐠𝐞 𝐨𝐟 𝐭𝐡𝐞 𝐚𝐦𝐨𝐮𝐧𝐭 𝐨𝐟 𝐝𝐫𝐮𝐠 𝐢𝐧 𝐭𝐡𝐞 𝐟𝐢𝐫𝐬𝐭 𝐜𝐨𝐦𝐩𝐚𝐫𝐭𝐦𝐞𝐧𝐭 =𝐑𝐚𝐭𝐞 𝐨𝐟 𝐢𝐧𝐩𝐮𝐭𝐬 𝐢𝐧𝐭𝐨 𝐭𝐡𝐞 𝐟𝐢𝐫𝐬𝐭 𝐜𝐨𝐦𝐩𝐚𝐫𝐭𝐦𝐞𝐧𝐭 − 𝐑𝐚𝐭𝐞 𝐨𝐟 𝐨𝐮𝐭𝐩𝐮𝐭𝐬 from the first compartment
- 𝐚𝐭𝐞 𝐨𝐟 𝐜𝐡𝐚𝐧𝐠𝐞 𝐨𝐟 𝐭𝐡𝐞 𝐚𝐦𝐨𝐮𝐧𝐭 𝐨𝐟 𝐝𝐫𝐮𝐠 𝐢𝐧 𝐭𝐡𝐞 𝐬𝐞𝐜𝐨𝐧𝐝 𝐜𝐨𝐦𝐩𝐚𝐫𝐭𝐦𝐞𝐧𝐭 =𝐑𝐚𝐭𝐞 𝐨𝐟 𝐢𝐧𝐩𝐮𝐭𝐬 𝐢𝐧𝐭𝐨 𝐭𝐡𝐞 𝐬𝐞𝐜𝐨𝐧𝐝 𝐜𝐨𝐦𝐩𝐚𝐫𝐭𝐦𝐞𝐧𝐭 − 𝐑𝐚𝐭𝐞 𝐨𝐟 𝐨𝐮𝐭𝐩𝐮𝐭𝐬 from the second compartment
What is the equation to determine the concentration of a 2 com system?
What is the difference between Ae^-at and Be^-bt?
A: distribution
B: elimination
What are the micro-rate constants?
k10, k12, and k21
What are the macro rate constants?
A, B, a, and b
What are micro-rate constants for?
- Relate the amount of drug being transferred from one compartment to another.
- Required to calculate the apparent volumes of distribution (V1 & V2): central and peripheral
What is distribution half-life?
What is the elimination half-life?
What does distribution half-life used for?
To determine how long a drug takes to distribute from central to peripheral compartment
How do you find AUC using macro and micro rate constants?
