Basics

Question 1

Pharmacokinetics

Answer 1

What the body does to the drug. 
Involves:
Absorption 
Distribution
Metabolism 
Elimination

Question 2

Mechanism of action

Answer 2

Drugs doing their job at the receptor site. They bind to cellular reception sites. Drug-receptor binding is reversible, selective (affinity), and graded.

Question 3

Affinity

Answer 3

Drug-receptor binding is selective.

Question 4

Agonist

Answer 4

Binds and produces a result

Question 5

Antagonist

Answer 5

Binds and blocks an activity

Question 6

Passive diffusion

Answer 6

Molecules can move from one side of a barrier to the other without using energy. Move down a concentration gradient from an area of high concentration to low concentration solubility of drug must match absorption site (lipophilic). Has better outcome if drug molecule is non-ionized and in same pH.

Question 7

Active transport

Answer 7

Requires energy. Protein membranes of the cell can act as carrier membranes. Works if the solubility doesn’t match. But must share molecular similarities.

Question 8

Bioavailability

Answer 8

The fraction of the drug that reaches the systemic circulation.
Dependent on solubility, chemical structure, size, polarity, and presystemic biotransformation.

Question 9

First pass metabolism

Answer 9

When taken orally, some of it will pass through the hepatic circulation through the portal vein. Sometimes it is cleared by the liver before it ever reaches the systemic circulation. Have to give a higher PO dose than IV because it has a higher first-pass metabolism.

Question 10

Absorption

Answer 10

First step in pharmacokinetics. Getting into the body. Dependent on first-pass metabolism, food, surface area, and drug size.
Affected by solubility, chemical structure, polarity, route, site, bioavailability, peak blood flow,

Question 11

Distribution

Answer 11

The 2nd step in pharmacokinetics. After absorption, it is transported to its site of action. Drugs bind to proteins (usually albumin) in the circulatory system. Highly bound drugs (to protein) are less available for action. Low binding drugs have higher distribution.

Less available protein, more free drug and higher chance for toxicity.

Barriers: blood-brain barrier and placental barrier

Question 12

Hypoalbuminemia

Answer 12

Albumin is the protein that most drugs bind to. If not enough protein, there are fewer binding sites, and there is more free drug, increasing toxicity.

Question 13

Metabolism/ Biotransformation

Answer 13

3rd step in pharmacokinetics. Drug is where it needs to be now needs to be transformed. This is the process of chemically changing a drug to a different compound called a metabolite. Want to increase water solubility and decrease lipid solubility.
Affected by age, genetics, gender, diet, disease states.

Question 14

CYP450 enzymes

Answer 14

Found in the lipophilic ER membranes of the liver. They are involved in the biotransformation of drugs in the metabolism phase.
Enzyme Induction and Enzyme Inhibition

Question 15

Elimination

Answer 15

4th phase of pharmacokinetics. The excretion and their transport outside the body. A drug is removed from tissues and circulation.

Renal excretion most common. Needs to be water-soluble. Removes drug that is unbound and free in plasma. Glomelular in the filtration.

Biliary excretion- transported by liver cells from blood to bike then enter GIBtract and excreted through feces.

Question 16

Half-Life

Answer 16

The amount of time over which the drug concentration in the plasma decreases to 1/2 of the original value. Ultimately determines how often a drug is administered. Takes 4-5 half-lives to reach steady state concentrations during continuous dosing of a drug.

Question 17

Enteral absorption

Answer 17

Oral route of administration. Non-ionized drugs diffuse passively down a concentration gradient for the higher. Concentration (GI tract) to a lower concentration (blood)

Question 18

Biotransformation

Answer 18

Enzyme induction- some drugs can induce or stimulate production of the enzymes to increase metabolism (decrease amount of drug circulating in the body)
Enzyme inhibition- drugs inhibit the production of CYP enzymes and decrease drug metabolism.

CYP450 enzymes- found in lipophilic ER of liver

Factors that affect it: age, genetics, gender, diet, environment, and disease state.