21 Pharmacodynamics

Pharmacodynamics describes what?

What the drug does to the body

Pharmacokinetics describes what?

What the body does to the drug

PK/PD relationship refers to what?

The relationship between drug exposure and response

PK/PD response depends on what?

PK, pharmacology, and physiology

The three PK/PD pillars include which set?

PK, pharmacology, physiology

Concentrations correlate better with PD effect than doses because?

Concentrations reflect actual drug at the site of action

Therapeutic window refers to what?

Concentration range effective without toxicity

A narrow therapeutic window means what?

Small safe range → high toxicity risk

A quantal response is defined as what?

An all-or-none effect

Example of a quantal response?

Suppression of a cardiac arrhythmia

A graded response is defined as what?

Continuous response that increases with dose

Example of a graded response?

Blood pressure reduction

Three components of concentration–response relationship?

Intensity, onset, duration

Intensity of effect benefits include what?

Expands lower range where small concentration increases → large effect change

Higher Hill coefficient (γ) causes what?

Steeper curve, more quantal-like

Onset of effect means what?

Time to pharmacodynamic response

Onset of effect occurs when?

Concentration > Cmin

Units of onset of effect?

mg/L

Minimum amount in body (Amin) refers to what?

Least amount of drug (not concentration) needed to produce effect

Below Cmin and Amin, what happens?

No response occurs

Duration of effect lasts as long as what?

Concentration > Cmin AND amount > Amin

Clinical application of duration of effect?

Antibiotic efficacy requires time above MIC

β-lactam efficacy correlates with what?

Duration above MIC