pharmacokinetics

Question 1

what are xenobiotics

Answer 1

xenobiotics are drugs and have no nutritional value

Question 2

explain the journey of a drug

Answer 2

orally administered
then sme of the drug passes through the feaces without being absorbed
some drug is absorbed (first pass metabolism)
so the bioavailibility is lost
free drug in systemic circulation then travels to the site of action
SOME OF THE DRUG WILL BE TAKEN UP BY TISSUE DEPOSITS (STORED)
the drug comes back from the site of action into the blood and goes to the liver to be metabolised
after metabolism its excreted
some drug is excreted without being metabolised
excretion happens in the kidney

Question 3

what does absorption and disintigration and distribution do to the concentration of the drug?

Answer 3

increase it

Question 4

what do metabolism and excretion and storage do to the concentration of the drug?

Answer 4

decrease it

Question 5

what do the absorption and metabolism and distribution of a drug depend on?

Answer 5

the route of administration such as intravenous or oral

AND the physiochemical properties of the drug

Question 6

what are the physiochemical properties of a drug (drug)

Answer 6

molecular structure
molecular weight
lipophiclity (absorbed straight through membrane or not?)
ionisation

Question 7

what are the physiological properties (body) that affect absorption?

Answer 7

• mesenteric blood flow
• gastric emptying
• presence of food
• surface area of the membrane
• any transporter (efflux) proteins
• pH of the site

Question 8

what is bioavailibility?

Answer 8

how much of the drug (unchanged/active) is present after passing first face metabolism and then absorption
varies from 0-100%

Question 9

administration can be…

Answer 9

enteral or oral or intravenous or intraarterial or intramuscular or intra peritoneal or intrathecal (spinal) or intrasubcutaneous or intra epithelial (lungs or skin) OR TOPICAL

Question 10

what does oral/enteral mean

Answer 10

occurring through the epithelium of the GI tract so can be oral or anal - normal oral spray or a suppository (through anus)

Question 11

what does topical administration mean

Answer 11

applying medication to the site of action e.g. skin, vagina, eyes, nasal mucosa, airways

Question 12

paracetamol, diazipam, morphine and ethanol have what in common in drug distribution?

Answer 12

all lipid soluble so can pass through the whole body water easily

Question 13

which drug has a high molecular weight?

Answer 13

heraprin

Question 14

which drug is 99% bound to proteins?

Answer 14

warfarin

Question 15

turbocurain (neuromuscular blocker) is highly ionised so…

Answer 15

restricted to extracellular fluid only, cant go inside cells

Question 16

what is protein binding

Answer 16

loose electrostatic binding of proteins with the drugs

albumin with basic drugs and acid glycoproteins with basic drugs

Question 17

which drugs are 90-99% protein bound?

Answer 17

warfarin, diozoxide noninflammatory drugs and non steroidal drugs

Question 18

what does protein binding do?

Answer 18

establishes equillibrium between free drug and protein bound drug and it decreases the amount of free drug in the plasma to reach its site of action

Question 19

what are the 3 main ways of elimination?

Answer 19

renal excretion
liver metabolism
chemical transformation

Question 20

which drugs pass straight through the glomerular filtration and are excreted?

Answer 20

small water molecules (drugs
and
complex carbohydrates drug

Question 21

which drugs need to be extensively metabolised

Answer 21

lipophilic drugs otherwise they would keep getting reabosrbed by the digestive and renal system

Question 22

whats phase 1 metabolism?

Answer 22

functionalisation reactions

Question 23

phase 2 metabolism

Answer 23

conjugation reaction

Question 24

phase 3 metabolism

Answer 24

formation of xenobiotics