Pharmacokinetics II Vocabulary

Comprehensive vocabulary flashcards covering basic and clinical pharmacokinetic terms, mathematical models, equations, and parameter definitions based on lecture materials.

Pharmacodynamics

The branch of pharmacology that studies what the drug does to the body.

Pharmacokinetics

The branch of pharmacology that studies what the body does to the drug, comprising absorption, distribution, metabolism, and excretion (ADME).

Apparent Volume of Distribution ($V_d$)

The volume of a virtual homogeneous fluid compartment in which the concentration of a drug appears the same as measured in blood or plasma, defined as $V_d = \frac{M}{c_{\text{plasma}}}$.

Plasma Volume Reference Value

The reference volume of plasma expressed per kilogram of body weight, equal to $0.04proposal\text{ l/kg}$ (or $0.04 \times \text{l/kg}$).

Total Body Water Volume Reference Value

The reference total body water volume expressed per kilogram of body weight, equal to $0.6\text{ l/kg}$ (or $0.6 \times \text{l/kg}$).

Clearance ($CL$)

The volume of blood cleared of drug by metabolism or excretion per unit of time, serving as the constant velocity factor of elimination.

First-Order Kinetics

Pharmacokinetic model where the elimination velocity of a drug is directly proportional to its blood or plasma concentration, resulting in an exponential decrease over time.

Elimination Coefficient ($k_{\text{el}}$)

The parameter showing the partial drop of drug concentration per unit of time, calculated as $k_{\text{el}} = \frac{CL}{V_d}$.

Half-Life ($T_{1/2}$)

The time required for the plasma drug concentration to decrease by 50\text{\null}\null\text{\%}, calculated as $T_{1/2} = \frac{\text{ln}(2)}{k_{\text{el}}} = \frac{V_d}{CL} \times \text{ln}(2)$, where $\text{ln}(2) \thickapprox 0.693$.

Area Under the Curve (AUC)

The integral of the plasma concentration-time curve, directly proportional to the total amount of drug reaching systemic circulation, related to clearance by $CL = \frac{M}{\text{AUC}}$.

Zero-Order Kinetics

Non-linear pharmacokinetic model where the rate of elimination is constant and independent of concentration due to saturation of elimination processes.

Bioavailability ($f$)

The fraction of unchanged drug reaching the systemic circulation, calculated as $f = \frac{\text{AUC}_{\text{other}}}{\text{AUC}_{\text{iv}}}$.

Alpha ($\alpha$) Phase

The initial rapid phase in a multi-compartment open model characterized by the fast inflow and distribution of a drug into the peripheral compartment.

Beta ($\beta$) Phase

The terminal phase in a multi-compartment open model determined mainly by the rate of elimination of the drug.

Dominant Half-Life

The half-life corresponding to the phase that accounts for the largest portion of the total AUC in a multi-compartment model.

Steady-State Concentration ($C_{ss}$)

The stable drug concentration achieved in tissues when the rate of drug administration equals the rate of elimination.

Maintenance Dose ($D$)

The dose administered at fixed intervals ($T$) to maintain steady-state drug concentration, calculated as $D = \frac{C_{ss} \times CL \times T}{f}$.

Loading Dose ($D_{\text{loading}}$)

An initial larger dose given to achieve target steady-state plasma concentration rapidly, calculated as $D_{\text{loading}} = \frac{C_{ss} \times V_d}{f}$.

Plasma Level Fluctuation

The variation between maximum and minimum steady-state concentrations ($c_{\text{max}} - c_{\text{min}}$), which is directly proportional to single dose and inversely proportional to volume of distribution ($c_{\text{max}} - c_{\text{min}} = \frac{D}{V_d}$).