Pharmacokinetics and Pharmakogenomics Flashcards
Name 6 ways drugs can be administered?
- Topical
- Rectal
- Oral
- Sublingual
- Inhalation
- Parenteral (IV, SC, IM)
How are drugs typically abosred? Which transport method?
Passive Diffusion
Are most drugs weak or strong acids/bases?
Weak Acids/Bases
What is pharmacokinetics?
What is pharmacodynamics?
Pharmacokinetics - what the body does to the drug
Pharmacodynamics - what the drug does to the body
What is the therapeutic window in terms of pharmacokinetics?
The therapeutic window is when the drug concentration is high enough to produce a miniumum effect and low enough to not produce an adverse effect.
What is bioavailablity?
The fraction of orally administered drug that reaches the systemic circulation.
What are 4 factors that effect drug distribution?
- Blood Flow
- Capiallary Permeability
- Binding of drugs to plasma proteins
- Hyrophobic and hydrophilic drugs
What is the two compartment model?
What are alpha phase and beta phase?
The two compartment model is how drug concentrations in the blood change after administration of the drug
Alpha Phase - a rapid decrease in concentration due to drug dispersing to tissues and peripheral systems
Beta phase - a gradual decrease in concentration due to the degradation of the drug by metabolic pathways and excretion.
What is a phase I type of reaction?
What is a phase II type of reactoin?
Phase I - oxidation, hydroxylatoin, dealkylation, or deamination.
Phase II - conjugation with the addition of large subsituent groups.
Which types of enzymes are most important in drug metabolism?
Cytochrome P450 enzymes.
What is first-order kinetics regarding drug metabolism?
What is zero-order kinetics regarding drug metabolism?
How does the half-life of the drug compare between first and zero order kinetics.
First Order - the rate of the enzyme metabolism is proportional to the concentratoin of the drug.
Half-life is independent of concentration. The drug will always degrade at the same rate.
Zero Order - the rate of the enzyme metabolism will not change (remain at Vmax) regardless of drug concentration.
There is no fixed half life for zero order
What are the 2 parameters that describe pharmacokinetics?
-
Volume of Distribution - describes how much of a drug is in the body compared to the blood. Lower the Vd, the more in blood. The higher the Vd, the more in the tissues.
- amount of drug in the body / drug-plasma concentration (Liters)
-
Clearance - predicts the rate of drug elimination
- Volume of plasma cleared of drug per unit time. (liters/hr)
What is steady state in terms of pharmacokinetics?
How does the steady state compare to the rate of constant infusion and drug clearance? Are they porportional or inveserly proportional?
Steady State - The equllibrium drug concentration established between the drug infusion rate and the bodys drug metabolism rate.
Rate of Infusion - the Steady state is directly proportional to the rate of infusion. If you double the rate, the steady state concentratoin will double.
Drug Clearance Rate - the steady state is indirectly proportoinal to the clerance rate. If you reduce the clearance rate (defective kidney), the steady state concentration will increase.
Will a higher rate of infusion reduce the time to achieve a steady state drug concentratoin?
No. The drug’s half-life is independant of drug concentration.
Why should pateints be gentically tested prior to administration of medications?
Pateints have degrees of genetic variation between:
- A drugs target enzyme/receptor
- The metabolic enzyme that degrades that drugs
These genetic variations can have varying effects:
- Metabolize the drug to fast or too slow
- The actual drugs effects could be increased or decreased
- This can lead to adverse effects.
