PHARMACODYNAMICS, PHARMACOKINETICS, PHARMACOGENETICS, ADVERSE DRUG REACTIONS & DOSING REGIMENS

Question 1

Define Agonist

Answer 1

Medication/drug that causes something to happen (salbutamol, mimics adrenaline)

Question 2

Define Antagonist

Answer 2

Something that opposes/blocks an action

Question 3

What is CYP450?

Answer 3

An enzyme that the liver produces, enabling the liver to break down medications

Question 4

Define Pharmacodynamics

Answer 4

What the drug does to the body. The Interaction between a drug & its molecular target and the resulting pharmacological responses

Question 5

Define Pharmacokinetics

Answer 5

Movement through the body (absorption, metabolism, secretion, excretion) (What the body does to the drug)

Question 6

Define Bio-Availability

Answer 6

The amount of medication the body uses at the end. Depends on how the medication has been administrated (For example, IV, which can go straight into the bloodstream or oral, which absorb through the digestive system, then into the systemic circulation system

Question 7

What is Prodrug?

Answer 7

Some people may not have enough of CYP450 to convert codeine (for example) into morphine in the liver, which means patients may not be getting the full therapeutic dose of codeine to alleviate pain.
- A medication which is converted in the liver to the active drug

Question 8

What is the Hepatic First Pass and how does it work?

Answer 8

Medication travels down through the stomach, absorbed in the small intestine, absorbed in the liver before moving to the systemic circulation

An oral medication, most of the drug is absorbed in the small intestine, drug goes via the portal vein to the liver, the liver may ‘ditch’ some. Then the liver activates it using enzymes and sends it through to the systemic circulation system, and it is sitting in the plasma, these then bind to the albumin in the plasma. Only a certain amount of the drug is ended through to the systemic circulation system.

(refers to the amount of drug removed by the liver following its oral absorption in GI system)

Question 9

What percent of IV medications are available to the bloodstream and why is this?

Answer 9

100% of IV medications are available to the bloodstream, as the medications are administrated via IV goes directly into the systemic circulation, meaning they bypass the digestive system

Question 10

Define Generic Name

Answer 10

Actual name of the drug (e.g. amlodipine), the official name listed in publications and used for prescribing

Question 11

Define Trade Name

Answer 11

Marketed name - the name that the drug is marketed under; several different ways to name the generic drug (e.g. Norvasc)

Question 12

Define Chemical Name

Answer 12

Describes the chemical composition.

Question 13

List the four main types of proteins that drugs act on

Answer 13

Carrier (transporter)
enzyme
ion channel
receptor

Question 14

Define Drug Absorption

Answer 14

the process by which the unchanged drug proceeds from the site of administration into the blood

Question 15

What VARIABLES effect drug absorption?

Answer 15

drug solubility
drug ionisation
drug formulation (SR, CR, ER)
physiological factors (blood flow, rapid intestine transit time, food in stomach, stomach pH)

Question 16

Define drug distribution

Answer 16

the process of reversible transfer of the drug from the blood into other body compartment

Question 17

What are 4 factors that impact drug distribution

Answer 17

Capillary permeability
plasma protein binding
cardiac function
tissue binding

Question 18

Define drug clearance

Answer 18

refers to the time taken for the drug to be eliminated from the body

Question 19

Using reference to pharmacokinetic and pharmacodynamic principles explain why therapeutic drug monitoring is required for some drugs

Answer 19

Monitoring is required in some drugs due to the risk of toxicity.

Question 20

Define Half-Life

Answer 20

is the main time taken for blood drug plasma concentration to fall by 50% of its original value

Question 21

What is the significance of a Half-Life?

Answer 21

is that it is determined of the action duration of a drug after a single dose, the time taken to reach steady state with chronic dosing and the dosing frequency required to avoid massive fluctuation in plasma drug.

Question 22

What factors can influence a half-life?

Answer 22

volume of distribution
clearance

Question 23

Define Metabolism

Answer 23

the process by which the drugs are made less lipophilic (more hydrophilic) for more efficient elimination by the kidneys. The liver is the main site of metabolism of the drugs. Main enzyme—CYP450

Question 24

What factors influence drug metabolism?

Answer 24

Age (↓hepatocytes, ↓enzyme)
genetic (deficiency of enzymes i.e. codeine)
disease state (HF, shock, hepatitis, cirrhosis)
diet & environmental factors (grapefruit)
drug interactions

Question 25

Define Drug excretion

Answer 25

Excretion is a process whereby drugs or metabolites are irreversibly transferred from the internal environment to the external environment through a renal or non-renal route.