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?
How do you calculate total clearance?
How do you calculate distributional clearance?
What is distributional clearance?
Clearance of the drug between the involved compartmens
How do you calculate C0?
