7: Pharmacology, Pharmacokinetics, Metabolism Flashcards
drugs not synthesized within the body
xenobiotics
Who said the dose makes the poison?
Theophrastus Von Hohenheim (Paracelsus)
actions of the drug on the body; group in which drug belongs
pharmacodynamics
*think Drug’s effect on the body = D
actions of the body on the drug (absorption, distribution, metabolism, and elimination ) aka ADME
pharmacokinetics
Flux (molecules per unit time) = (c1-c2) x ((area x permeability coefficient))/thickeness
Fick’s Law of Diffusion
category of drug absorption expressed as fraction of dose administered; also known as the fraction of unchanged drug reaching circulation
Oral Bioavalability (F)
(area under curve)
How are most toxicants absorbed by the body?
Simple diffusion
True/False:
Only the unbound drugs (those not bound to proteins) distribute into tissues and receptors, exert pharmacological effects, and are metabolized
True
The elimination rate constant; a function of clearance and volume of distribution
KEL
Cl = Vd x KEL
A constant relating to drugs rate of transfer/elimination from plasma; units are mL/min
Clearance
Cl = kel/Cp
Is clearance used for zero order or first order eliminated drugs?
first-order
Type of elimination where processes are saturated (going as fast as they can
-Constant rate of elimination; think of a tub; linear
zero-order elimination
i.e. Ethanol
Type of elimination where processes are not saturated; not linear
first-order elimination
Time for plasma concentrations to become ½
half life, T1/2
Is clearance used for zero order or first order eliminated drugs?
first-order
Calculation for half-life
T1/2 = 0.693/KEL
hypothetical volume of body fluid (plasma) necessary to contain all of the drug at a concentration equal to the plasma concentration
Apparent Volume of Distribution, Vd
Vd of drugs that distribute in total body water (plasma + water)
0.7 L/kg male and 0.55 L/kg females (EtOH**)
Route of Administration –>
Put in order of speed of delivery starting w/ fastest:
subcutaneous, IM, IV, Oral
(fastest) IV, Intramuscular, subcutaneous, oral (slowest)
when the quantity of drug eliminated in the unit of time equals the quantity of the drug that reaches the systemic circulation in the unit of time.
Steady State