Pharmacokinetics

Lecture Notes No. 4
Pharmacology and Pharmacokinetics



Part 3
Pharmacokinetics

, 1. What mechanism led to Mr. R's pulmonary congestion and pedal edema?
2. Why was Mr. R given loop diuretics?
3. How do ACE inhibitors improve cardiovascular hemodynamics?
4. What other kinds of diuretics are available, and why were they not chosen in this acute setting?




Biopharmaceutics and
Pharmacokinetics
Pharmacokinetics
what the body does to the drug
physicochemical properties of drug affecting biological action

Nature of Drugs
Physical Nature : solid, liquid, gas
Drug size : 100-1000 MW (mostly)
Drug-receptor Bonds : Strong covalent, Weak electrostatic, Hydrophobic
Drug shape : Chirality


Pharmacokinetic Concepts
Permeation – drug permeates through the barriers to reach its site of action

1. Passive diffusion
– uncharged molecules
– requires concentration gradient

Fick's Law of Diffusion
Rate = (C1-C2) x Permeability coefficient x Area
Thickness

2. Special carriers
– very large, charged, insoluble molecules
a. Active transport – requires energy, selective, saturable