PD Flashcards
What is the “expected” glomerular filtration rate (GFR)?
125 mL/min
Why does the formula for estimating creatinine clearance ask us to x0.85 if the patient is female?
Females have decreased kidney functions compared to males, so their rate of clearance will be lower.
Define half-life.
Measured length of time required for a drug to decrease in plasma by one half (50%)
How many half-lives should pass before we consider the drug to be “cleared”?
4 half-lives
What does it mean when we say a drug is “unchanged” in ADME?
Biotransformation of the drug is not required for it to be excreted.
What is a loading dose?
Repeated or large doses of a drug given to quickly have plasma concentration reach the therapeutic range.
______ does are given after a loading dose in order to:
Maintenance; keep the drug within therapeutic range.
What are the 4 categories of factors that influence a patient’s response to drugs?
- Clinical factors
- Administration
- PK
- PD
What is ED50?
Median therapeutic dose; dose required to produce a therapeutic effect in 50% of the population.
What is TD50?
Median toxicity dose: elicits a toxic response in 50% of patients.
The therapeutic index (TI) of a drug is the ratio between the drug’s ____ and _____.
TD50 and ED50 (TI = TD50:ED50)
What are 4 notable drugs with narrow TIs?
- Digoxin (Lanoxin)
- Warfarin (Coumadin)
- Phenytoin (Dilantin)
- Tracrolimus (Prograf)
Most drugs bind to _____ in the body.
Receptors.
What are 3 characteristics of drug-receptor binding?
- Saturable.
- Can increase or suppress existing processes.
- Only blocks the receptor.
What are the 6 major receptor types?
Technically she combined 2 of them under 1 name so you should be able to list 5 names
- G-protein (GPCR)
- Ion channels
- Nuclear receptors.
4&5. Enzyme types. - JAKSTAT
Define receptor affinity.
Strength or length of binding.
Define drug efficacy.
Effectiveness; degree to which a drug induces the maximum therapeutic effect.
Do antagonists have any efficacy?
No: they only block the receptors, but do not elicit responses.
Define drug potency.
How much of a drug is required to elicit a certain therapeutic response.
What is an agonist?
A drug that mimics the endogenous substance, producing similar effects.
What is a primary or “full” agonist?
A drug that will extensively bind to the existing receptor(s), successfully eliciting the expected response.
What is a partial agonist?
Lower efficacy agonist: maximum response is smaller even if all receptors are occupied.
Why do we consider partial agonists to be antagonists when full agonists are present?
The partial agonist acts as competition for the saturable receptor sites, meaning the full agonist cannot elicit its full effects.
What are inverse agonists?
Drugs that bind to receptors and induce the OPPOSITE effects of the endogenous substance.
