Pharmacokinetics Flashcards
How must drugs travel from the point of entry to the brain?
Through the circulatory system
What influences how much of a drug gets to the brain and how fast it gets there?
The ability of the drug to travel through the body and reach the brain intact
What is pharmacokinetics?
Refers to the processes involved in the movement of drugs within biological systems with respect to absorption, distribution, metabolism, and excretion
What determines how big of an effect a drug will have?
Molecular structure of the drug (hydrophobic/hydrophilic), concentration of the drug at the site of action, dose administered, rate of accumulation
What is pharmacodynamics?
The biochemical and physiological effects of drugs and their mechanisms of action
Which term refers to the effects of drugs on the body and also the effects of the body on the drug?
1) pharmacodynamics
2) pharmacokinetics
What is absorption?
Refers to getting the drug from where it needs to go to the site of action (brain)
Drugs must pass through barriers before entering into the ______
Bloodstream
True or false: Drugs are generally too large to go through ion channels
True
What factors related to drugs influence absorption?
A lot of things, but the main three things are lipid water solubility, dosage forms, and concentration
What factors related to the body influence absorption?
Surface area of absorptive surface, vascularity, pH, presence of other substances, GI motility, functional integrity of surface, diseases
What influences how well a drug passes through a membrane?
Concentration and lipid/water solubility though the latter is the most important factor
Most drugs are soluble to some extent in both water and lipids. Why is this?
They need to be hydrophobic enough to cross membranes but hydrophilic enough to be transported through the bloodstream
What is the oil-water partition coefficient?
The relative solubility between oil and water = oil/water
What do higher oil-water partition coefficients mean?
That the molecule can more readily cross the membrane and dissolves less easily in water
The number of barriers a drug must go through depends on the _________
Route of administration
What are the 4 common routes of drug administration?
1) oral
2) injection
3) inhalation
4) absorption through the skin/membranes
What are three ways someone could inject a drug?
1) intravenous
2) subcutaneous
3) intramuscular
What are the 2 ways someone can inhale a drug?
1) smoking
2) vapor inhalation
What are the 3 ways someone can absorb a drug through the skin/membranes?
1) intranasal
2) sublingual
3) transdermal
Why is oral administration a long, dangerous journey?
In the stomach, drugs must withstand the stomach acid and degrading enzymes. Also, the drug must pass through the cells lining the walls of the GI tract. The majority of substance from the GI tract is sent to the liver where degrading enzymes are present.
What is the first pass effect?
This effect only applies to drugs taken orally and means that the drug is sent directly by the blood after GI tract to the liver for metabolism