Pharmacokinetics Quiz

Study Notes

After a single oral dose, a typical plasma drug concentration-time curve is obtained.
The curve showcases different phases: absorption, post-absorption, elimination.
The absorption phase is characterized by the rate constant Ka.
The peak plasma concentration (Cmax) and time of peak concentration (tmax) are key parameters in this phase.
The elimination phase is characterized by the rate constant K.
The therapeutic range is the desired concentration range for achieving therapeutic effects while minimizing side effects.

Cmax: The highest drug concentration achieved in the plasma after administration.
Cmax is influenced by the dose, absorption rate (ka), and elimination rate (k).
tmax: The time it takes to reach the peak plasma concentration (Cmax).
AUC (Area Under the Curve): Represents the total amount of drug absorbed after administration.

MEC (Minimum Effective Concentration): The minimum plasma drug concentration required to achieve the desired therapeutic effect.
Concentrations below MEC are considered sub-therapeutic.
MSC (Maximum Safe Concentration): Also known as the Minimum Toxic Concentration, indicating the plasma concentration beyond which side effects occur.
Concentrations above MSC are considered toxic.
Therapeutic Range: The range of plasma concentrations between MEC and MSC, ensuring therapeutic effects without significant side effects.
Onset of Action: The time it takes for the pharmacological response to begin, occurring when the plasma concentration exceeds the MEC.
Duration of Action: The time period during which the plasma concentration remains above the MEC, maintaining the therapeutic effect.
F (Fraction of Drug Absorbed): The ratio of the amount of drug reaching the plasma to the total dose administered.
F value is 1 when all the administered drug reaches the plasma.
Factors affecting F include: slow drug release, loss of unabsorbed drug, degradation in GIT, and first-pass metabolism.

Rate: The velocity of a chemical or physical reaction.
Expressed as the change in drug concentration over time: - dA/dt (forward reaction) or + dB/dt.
Order of a Reaction: Describes how concentration influences reaction rate.
Reaction rate = - K * Cn, where:
- dC/dt: rate of reaction
- K: rate constant
- n: order of the reaction (0, 1, 2, etc.)