Test 1 Flashcards
Pharmacodynamics
What a drug does to the critter
Pharmacokinetics
What the critter does to the drug
Pharmacokinetics: LADME
Liberation Absorption Distribution Metabolism Elimination
Two categories of drug administration
Enteral
Parenteral
Additive interaction
1+1=2
Synergistic reaction
1+1=3
Potentiation reaction
1+0=3
4 types of receptors
Regulatory proteins
Enzymes
Transport proteins
Structural proteins
3 aspects of drug receptor function
- Receptors determine the nature and characteristics of the drug concentration response curve
- Receptors function as regulatory proteins and part of chemical signaling mechanisms that provide targets for drugs
- Receptors determine the therapeutic and toxic effects of drugs on a critter
4 transmembrane signaling mechanisms
Ligand gated ion channels
G protein coupled receptors
Enzyme linked receptors
Intracellular receptors
How can differences in potency be overcome?
Giving more drug
Which is more important, potency or efficacy?
Efficacy
Therapeutic index
TD50/ED50
Toxic effect in 50% of population vs. therapeutic effect in 50%
Dangerous therapeutic index
<2
Definition of bioavailability
Fraction of administered drug that reaches systemic circulation
First pass metabolism
Via portal circulation
Liver metabolizes drugs limiting their bioavailability
Drugs with high first pass metabolism must be given in high doses orally or parenteral lay
Solubility characteristics of drugs
Too lipopholic: poorly absorbed
Too hydrophilic: difficulty passing through cell membranes
MOST COMMONLY ADMINISTERED DRUGS ARE WEAKLY ALKALINIC OR ACIDIC
Factors affecting bioavailability
Chemical stability in the GI tract
Drug formulation
3 factors affecting volume of distribution
Blood flow
Water/fat solubility
Protein binding
Major factor affecting sieving coefficient
Degree of protein binding
Volume of distribution calculation
Vd=D/Co
Dose/concentration
5 main ways to eliminate drugs
Urine Bile Hepatic metabolism Lung/oxygenator expiration Artificial filtration (hemoconcentrator)
Half life: 3.3, 4.3, and 4.3 years
- 3: 90%
- 3: 95%
- 3: 97.5%
Clearance rate equation
Cl= (0.693*Vd)/half life
Loading dose equation
LD= (Vd*target plasma concentration)/bioavailability
Maintenance dose equation
MD= (Clearance rate *target plasma concentration)/bioavailability