Pharmacokinetics

Question 1

Define Pharmacokinetics

Answer 1

The effect of the body on the drug

Study of the drug’s alterations as it is absorbed into, distributed through, metablised in and excreted from an organism

Question 2

Define a drug

Answer 2

A single chemical entity that may be one of the constituents of a medicine

Question 3

Defina medicine

Answer 3

either one or more active chemical entities (drugs) plus additives to facilitate administration

Question 4

What is the therapeutic index?

Answer 4

relationship between a deug’s therapeutic effect and adverse effects.

Question 5

give a an example of a drug in the ward which has a narrow therapeutic index?

Answer 5

heparin
gentomyicin
vancomyicin

Question 6

Why might it be undesirable to administer medication via an enteral oral route?

Answer 6

medication may be destroyed in the gut either via stomach acid or digestive enzymes etc.

distribution of drug may be very poor by blood stream therefore meds must be given directly into area i.e epidermal

drugs affecting the brain.

Question 7

in terms of pharmacokinetics what is the aim in the design of the drug?

Answer 7

that it is fat soluble at the time of it’s absorption

Question 8

What is usually prefererred rout of absorbtion for a drug?

Answer 8

diffusion

Question 9

Where is largest area of absorbtion via enteral route?

Answer 9

small intestine

Question 10

How much water should a patient frink to get medication from the mouth to the stomach?

Answer 10

250 mls of water

Question 11

If a patient does not drink a sufficient amount of water, and drug does not reach it’s area of expected area of absorption what will happen?

Answer 11

drug is not absorbed very well therefore you lose the drug effect.

May cause ulcerations and perforations

Question 12

What gastrointestinal factors which influence absorption?

Answer 12

oesophageal passage

the pH of the GI tract

Gastric motility

Question 13

What could happen to the medication if you take it before food?

Answer 13

Pylorus of stomach becomes closed off due to digestion in stomach.

Medication may become stuck in the stomach

Therefore medication cannot get into small intestine

Question 14

What is drug efflux?

Answer 14

a mechanism which involves drug efflux proteins which use energy to push drugs back into the intestine. limiting the absorption of fat soluble drugs via the intestinal walls

Question 15

where are drug efflex proteins found?

Answer 15

on the surface of epithelial and endothelial cells

Question 16

Where do drugs usually accumulate in the body?

Answer 16

in fatty areas - subcutaneous fat

Question 17

What is the most fat soluble type of medication?

Answer 17

anaesthetics

Question 18

List factors which could affect drug distribution in the body?

Answer 18

Blood flow in the tissue

Binding to plasma proteins

cellular binding

adipose store in the tissue

Question 19

What system carries blood from the digestive tract to the liver?

Answer 19

hepatic portal vein

Question 20

What organ is the least circulated?

Answer 20

skin

Question 21

What is plasma protein binding?

Answer 21

degree to which medications attach to proteins within the blood

Question 22

Give an example of a protein in the systemic circulation which may bind medication

Answer 22

albumin

Question 23

what is polypharmacy?

Answer 23

The simultaneous of multiple medications by a patient

Question 24

Last the disadvantages of protein plasma binding in terms of drug distribution

Answer 24

The efficiency of the drug

In the case of polypharmacy, there is risk of accumulation of drugs in the body.

Question 25

What is drug metabolism?

Answer 25

the breaking down of a drug in the body

Question 26

How many phases of drug metabolism are there?

Answer 26

2

Question 27

Describe Phase 1 metabolism

Answer 27

causes the breakdown of a molecuyl;e into more water soluble parts

Question 28

Describe Phase 2 metabolism

Answer 28

Adds on water conjugate molecules to make the whole complex water soluble.

Question 29

How much paracetamal can individual taken before getting a overdose?

Answer 29

4g

Question 30

What is cytochrome P450?

Answer 30

a phase 1 metabolic enzyme

Question 31

what is the main phase 1 metabolic enzyme you should remember for the exam?

Answer 31

cytochronme P450

Question 32

Why is cytochrome p450 such a significant phase 1 metabolic enzyme in the body?

Answer 32

responsible for metabolising >60% of all therapeutic drugs in the body.

Question 33

Why should patients on polypharmacy not drink grapefruit juice?

Answer 33

CYP450 is inhibited by a number of substances found in grapefruit juice

Question 34

What are the three ways in which drugs are eliminated from the plasma?

Answer 34

redistribution

liver metabolism

renal excretion

Question 35

What effect does overdoseing have on phase 2 metabolism>

Answer 35

Less phase 2 metablic enzymes are made to further change the metabolites of phase 1

Question 36

Whatis the main aim of kidney elimination of drugs?

Answer 36

To remove the non-metabolised drugs in the bloodstream

Question 37

What problem can intestinal flora cause on metabolising drugs?

Answer 37

May de-conjugate metabolised drug to liberate parent drug

Question 38

What is First-past effect?

Answer 38

process by which orally administered drugs progress from the intestinal lumen to the hepatic system before the general circulation

Question 39

What is bioavailability

Answer 39

Degree to which a drug is absorbed and reaches the general circulation.

Question 40

What is drug half life?

Answer 40

Time required to reduce the total amount of a drug in a person’s body by 50%