Pharmacodynamics Flashcards
1
Q
Pharmacodynamics
A
The biological effect a drug elicits
Essentially - what the drug does to the animal
increased heart rate
sedation
Analgesia
- In order for a drug to elicit an effect it has to reach the effect site in sufficient concentrations for a sufficient period of time
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2
Q
Pharmocokinetic Pharmacodynamic Relationship
A
- Toxic Concentrations:
- Vomiting, diarrhea, lethargy, most adverse effects
- Effective Concentrations
- lower than toxic
- Therapeutic window
- Cmin, Cmax maintained with in this window
- Ineffective Concentrations
- Therapeutic Failure
3
Q
Biologic Interactions
A
- Receptors
- morphine is a muscerinic receptor agonist
- Non-Receptors
- enzymes
- DNA
- Transporters
- Ion Channels
- Bacteria, parasite, virus
4
Q
Physical Interactions
A
Osmotic Gradients
Binding Hydrogen ions
5
Q
Pharmacodynamics: Dose-response
A
- Drug must reach the effect site in order to elicit an effect
- A minimum amount of drug is needed at the effect site in order to elicit a desired effect
- As the amount of drug at the effect site increases, the response typically increases until a maximum effect (Emax) occurs
- Once the Emax is reached further increases in the dose do not result in further increases in the desired effect
- duration will increases
- adverse effects may increase
6
Q
Quantal Dose-Response Curve
A
- The dose or concentration required to elicit a given effect
- yes or no response
- ED50:
- the dose eliciting a defined effect in 50% of the patients treated
- LD50:
- The lethal dose in 50% of the patients
- Therapeutic Index:
- (LD50)/(ED50)
7
Q
Therapeutic Index
A
- The larger the therapeutic index, the larger the difference between an effective dose and lethal dose
- typically acute toxicity
- However, other adverse effects may not be accounted for
- Additionally, many times zero lethality is the accepted goal.
