Pharmacology principles Flashcards
Minimum effective concentration
Concentration of the drug needed for the drug to have an effect on the body. (critical concentration)
Maximum tolerated concentration
The maximum concentration of a drug that can be tolerated by the body without any adverse effects
Clearence
Volume of plasma cleared of the drug per unit of time
First order kinetics
The rate of elimination is directly proportional to drug concentration
Zero order kinetics
The rate of elimination is not proportional to drug concentration.
Rate of elimination is a product of?
Plasma concentration and clearence
Steady state
Rate of elimination=rate of administration
IV dosing to steady state graph
Smooth curve up and plateauing when it reaches steady state.
Oral dosing to steady state graph
Fluctuates around steady state because you are not constantly being given the drug.
Volume of distribution
The volume into which a drug appears to be distributed with a concentration equal to that of plasma
Polar metabolites are more readily excreted. True or false.
True
Phase 1 metabolism
Adding a chemically reactive handle via oxidation, reduction or hydrolysis. Making the drug more polar.
Phase 2 metabolism
Adds an endogenous compound increasing the polarity e.g. glucorindation
CYP450 mono-oxygenases
Family of haem proteins located in the endoplasmic reticulum of liver hepatocytes. They mediate phase 1 reactions.
In CYP3A4, what do the 3,A and 4 represent?
3- gene family
A- gene subfamily
4- individual gene.
What do phase 2 reactions usually result in, where do they occur and give an example?
They usually result in inactive products. It occurs in the liver and an example is glucorindation. This is the adding of glucuronic acid to electron rich atoms on the substrate.
Renal excretion via filtration
Only unbound drugs can pass through the glomerulus. Have to have a molecular weight of less than 20,000.
Clearance by filtration= glomerular filtration rate x fraction of unbound drug
Two transporters that transport drugs into the nephron
Organic anion transporter and organic cation transporter.
Pro’s and cons of OAT or OCT
Pro’s- protein bound drugs can be excreted.
Con’s- They are saturable. Substances may compete with each other
Give examples of what the organic anion transporter may excrete
Acidic drugs e.g. penicillin, uric acid, thiazides
Give examples of what the organic cation transporter may excrete
Basic drugs e.g. morphine
Factors that influence reabsorbtion
Lipid solubility- higher the lipid solubility- more reabsorption
Polarity- more polar, more likely it it to be excreted
Urinary flow rate
Urinary pH- more acidic- basic drugs will be excreted. More basic- acidic drugs will be excreted
