ANTIBIOTICS Flashcards
What is pharmacodynamics?
What the drug does to the body
relationship with concentration of the drug and response obtained in a patient
What is pharmacokinetics?
What the body does to the drug
Describes ADME
Bioavailability
Fraction of administered dose that reaches systemic circulation
What is Bioavailability for IV
100%
- effects is immediate
- dose cannot be retrieved
What are some causes for less than 100% Bioavailability
-1st pass effect
-incomplete absorption
-distribution of drug that enters other tissues before it gets into systemic circulation
i.hydrophilic
ii hydrophobic
1st pass effect
-part of oral dose that is lost due to liver/gut metabolism
What is a phase I RXN
-parent drug converted into water loving drug by adding polar functional groups OH group or Thiol/SH group NH2 (amide, azanide)
What is phase II RXN
-conjugate parent drug with polar moiety such as glucuronate, acetate, and sulfate to increase water solubility
What is the generic name for drugs that are responsible for drug metabolism oxidation rxns?
CYP450
Ex. CYP3A4, CYP2C9
Define substrate
-drug that is metabolized by one of CYP450 enzymes
Ex. Acetaminophen is metabolized by CYP1A2
Define inducer
drug that increases activity of CYP450 enzymes
Ex. smoking increases activity of of CYP1A2
- increases metabolism of drug
- increases elimination of the drug
- decreases concentration of drug in the body
Define inhibitor
-drug that decreases the activity of one of CYP450 enzymes
Ex. fluvoxamine decreases the activity of CYP1A2
- decreases metabolism rate of drug
- decreases elimination rate of the drug
- increases concentration of drug in the blood
How many half lives does it take to reach steady state
4.5
What is steady state
rate of drug elimination = rate of administration
Total amount of drug remains unchanged over several dosing cycles
Clearance
- most important pharmacokinetic parameter!
- determines steady state of a drug
