Basic Principles Flashcards
Absorpiton
movement of drug from the site of administration to the blood
Distribution
delivery of drug from the blood to the target tissue
bioavailability
the amount of drug that reaches the target site in an active and usable form
Blood-Brain Barrier
Tight junctions require drugs to pass through cells to enter brain. Only non-ionized, high partition coefficient rugs can cross. Break down of barrier due to tumor/inflammation can increase permeability.
Blood-Testis barrier
Similiar to brain, drugs must cross through cells, have high permeability coefficients, non-ionized, free
Placental barrier
myth-babbies do not have the same metabolic power as adults, likely get just as much drug if not more as mother.
partition coefficient
how lipid loving vs water loving a drug is. the higher it is, the more lipid loving it is.
Where should you sample if you suspect overdose with acidic drug? Where should you sample if you suspect overdose with basic drug?
Acidic drugs should be sampled in the blood, basic drugs in the stomach, regardless of route of administration.
Pharmacodynamics
What the drug does to the body
Pharmacokinetics
What the body does to the drugs. This is what allows us to predicts size, frequency of dose.
Rate of elimination
The amount of drug in the body, relative to the amount of time. the exponent is due to first order kinetics. elimination occurs at a constant RATE, rather than a constant QUANTITY. X=X_0 e^(-kt)
1st order kinetics
constant rate of material being removed
0 order kinetics
constant amount of material removed.
Half Life
t(1/2)= .693/Kel
Apparent Volume of distribution
a theoretical number that describes how the drug penetrates the tissue. 3-5L stays in the plasma, 12-15 l, entered the interstitium, not the cells, 30-40L distributed throughout the body, >50L, accumulated somewhere. Assume normal clearance.
