Pharmacodynamics

Pharmacodynamic Phase of drug action nursing lecture notes

Pharmacodynamics
What the drug does to the body
Primary effects – desired effects
Secondary effects – may be desirable or undesirable
Dose Response – dose needed to produce desired response
Maximal efficacy – maximum drug effect


Onset, Peak, Duration


Receptors
Drugs act at receptors to produce or block a response
Agonists – drugs that produce a response
Antagonists – drugs that block a response

Cholinergic Receptors

Alpha and Beta Receptors


4 Categories of Drug Action
Stimulation or Depression
Replacement
Inhibition or Killing of Organisms
Irritation

Therapeutic Index
Safety margin of the drug
Low or narrow = greater danger of toxicity
Example: Digoxin (0.5 – 2.0ng/ml)


Peak & Trough Levels, Loading Dose
Peak level – highest plasma concentration of a drug
Trough level – lowest plasma concentration of a drug
Loading Dose – large initial administration to achieve minimum effective concentration of a drug


Effects
Side effects – effects not related to desired effects of the drug
Adverse reaction – more severe than side effects
Toxic effects – adverse effects - depends upon drug