Drug Interactions Flashcards
What are pharmacokinetic considerations?
Drug availability.
What are pharmacodynamic considerations?
Interactions with receptors.
What are product monographs?
Manufacturer issued list of drug interactions.
What does it mean if the TI is small?
Small changes in responsiveness to a drug lead to toxic outcomes.
What is antagonistic interaction?
Drug A may act as an antagonist at a receptor for drug B, reducing effectiveness.
What kind of drug interaction is Vitamin K and Warfarin?
Antagonistic.
How is clotting measured?
Using prothrombin time; measure of the time required for blood to clot. Less time: thicker blood and stroke risk. Longer time: Bleeding risk.
What is INR?
International Normalized Ratio (ratio of clotting time compared to normal clotting time)
What is synergism?
Drugs together have a stronger effect than the sum of their parts. ACT ON SAME RECEPTOR
What is additive effect?
Drugs together have the same effect as the sum of their parts. ACT ON SAME RECEPTOR
What are examples of drug interactions resulting from drugs acting on the same receptor (syn. / additive)
Barbituaties/alcohol/benzodiazepines and GABA-A modulators.
What are indirect interactions?
The effect of multiple drugs influence the same signaling pathway (but not necessarily same receptor)
What kind of interaction is serotonin syndrome?
Polydrug use of psychoactive/serotonin preserving drugs lead to overstimulation of 5-HT2A and 1A receptors.
What are pharmacokinetic interactions that alter drug availability?
- Drugs that alter gut motility can alter absorption of a drug.
- Drugs that alter local blood flow can alter the absorption of a drug.
What interaction is seen between lidocaine and epinephrine?
Localized effects of lidocaine.
