(2.2) Pharmahodynamics Flashcards
What are the four types of drug-drug interactions?
- Pharmacokinetic
- Pharmacodynamic
- Drug-disease
- Drug-food
How does pharmacodynamic often affected by drug-drug interactions? Give 5 major classes of drugs which do this.
Via actions on receptors
- Anticoagulants
- Antidepressants
- Antiarrhythmics
- Antibiotics
- Anticonvulsants
Suggest 3 major diseases that affect drug-drug interaction. Each suggest an example how.
- Renal disease: -GFR -> -elimination, especially worsen by NSAIDs & ACEis
- Hepatic disease: - proteinsynthesis -> -metabolism, e.g. hypoalbuminea or cirhosis
- Cardiac disease: - organ perfusion & -GFR
What are the two types of Adverse Drug Reactions? Explain their difference.
- On target: targeted receptors found in other tissues -> exaggerated effects
- Off target: also act on to receptor subtypes -> metabolites production / immune response
How is Therapeutic Index calculated?
Toxic Dose (TD50) / Effective Dose (ED50)
Suggest 4 drugs that have narrow therapeutic window
- Warfarin
- Digoxin
Aminophylline
Aminoglycosides
What is p-glycoprotein?
ATP-dependent efflux pump, important in drug resistant cancer cells
What is the affinity of a drug? How is it measured?
- Ability of a drug binds to its receptor
- By Kd (conc at which 1/2 receptors occupied)
What is the potency of a drug? How is it measured?
- Overall response of a drug
- By EC50 (conc at which 1/2 max effect produced)
What is the efficacy of a drug?
The maximal effects
What is a Partial Agonist?
A drug that can’t produce a maximal effect even with full receptor occupancy
Which drug should people avoid drinking Cranberry Juice and why?
- Warfarin
- Cranberry juice is a CYP inhibitor -> + risk of haemorrhage
Suggest 4 drugs that bind to plasma albumin
- Warfarin
- NSAIDs
- Sulphonamides
- Tricyclic antidepressant
What are the 4 major drug targets in the body?
- Receptors
- Enzymes
- Transporters
- Ion channels
What is Specificity in terms of receptor binding?
The complementary of a drug and its receptors e.g. good drug only works on one receptor
What is Selectivity in terms of receptor binding?
The ability to produce desired therapeutic effects, measured with specific therapeutic indices e.g. good selectivity has minimal side effects
How should you start an initial dose for an
- overweight patient
- underweight patient
- Overweight: start at normal dose then maybe work up from there
- Underweight: start at
Three drugs with volume of distributions of the followings, in which fluid compartments are they likely to be found?
- 0.12L/kg
- 0.26L/kg
- 3..4L/kg
- 0.12L/kg in Plasma only
- 0.26L/kg in Extracellular fluid (plasma + interstitial)
- 3..4L/kg in Extra+Intracellular
