drug interactions

Question 1

Why might multiple drug therapy be used?

Answer 1

1. combination is better than a single agent. for instance in cancer chemotherapy.
2. Patient may have more than 1 disease.
3. Drug B many reduce/ block the side effects of drug A

Question 2

What does polypharmacy mean?

Answer 2

Polypharmacy, defined as regular use of at least five medications.

Question 3

What is Additivity?

Answer 3

When a combination of two or more chemicals is the sum of the expected individual responses.

Question 4

What is antagonism?

Answer 4

exposure to one chemical results in a reduction in the effect of the other chemical.

Question 5

What is potentiation?

Answer 5

exposure to one chemical results in the other chemical producing an effect greater than if it is given alone.

Question 6

What is synergisim?

Answer 6

Exposure to one chemical causes a dramatic increase in the effects of another chemical.

Question 7

Why should penicillin and aminoglycoside never be placed in the same infusion liquid?

Answer 7

Forms an inactive complex.

Question 8

Pharmacodynamics is the study of what?

Answer 8

the effects of the drugs and their mechanism of action.

Question 9

Drugs competing or the same receptor site can involve what sort of interactions?

Answer 9

agonist - antagonist interactions

agonist - partial agonist interactions

Question 10

what is cross tolerance?

Answer 10

when there is altered receptor numbers or affinity due to one drug affecting the actions of another.

Question 11

What is propanolol or atenolol used for? what are the pharmacodynamic concequences of using these with salbutamol or terbutaline?

Answer 11

Beta blockers used to treat hypertension and angina.

interfers with the action of sabutamol an terbutaline as tehy are Beta receptor agonists so competing for the same receptors.

Question 12

Pharmacokinetic interactions are?

Answer 12

where there is alterations to the concentrations of the drug that reaches the receptor.

Question 13

ADME stand for?

Answer 13

Absorption
Distribution
Metabolisim
Excretion/Elimination

Question 13

ADME stand for?

Answer 13

Absorption
Distribution
Metabolisim
Excretion/Elimination

Question 14

what are some examples of interactions that decrease free drug concentration in the gut lumen?

Answer 14

Tetracyclines + di- or tri-valent cations form insolube complexes

Cholestryramine interact with drugs such as warfarin leading to decreased absorption.

Question 15

How does food interact with Drugs pharmacokinetically?

Answer 15

can cause drugs to be more slowly absorbed as the progress to the small intestine is delayed.

Question 16

What are drugs that alter the Gastrointestinal motility?

Answer 16

Anticholinergics - slow gastric emptying, decrease motility, increase Tmax, decrease Cmax, AUC not altered.

Metoclopramide- increases gastric emptying, increases the Gi motility, decreses Tmax, Increases Cmax, AUC is not altered

Question 17

what is the interaction between antibiotics and oral contraceptives?

Answer 17

antibiotics kill bacteria in the gut, this leads to oestrogen conjugates not being hydrolysed and thus not being reabsorbed. This means less oestrogen thus a loss of the contraceptive affect. (does not have any effect on the progesterone component.

Question 18

What is the wine and cheese reaction?

Answer 18

A acute attack of hypertension that occurs in a person taking monoamine oxidase inhibitors (MAOI’s) when they eat something such as cheese which contains tyramine.

Question 19

What is the name of the family of enzymes that metabolise drugs in the liver?

Answer 19

CYP450

Question 20

What effect do p450 inhibitors have?

Answer 20

they decrease drug metabolism and thus increase bioavailability.

Question 21

What effect on p450 does heavy smoking have and why?

Answer 21

increased activity of p450. more aromatic hydrocarbons (from tobacco smoke) get carried into nuclear membrane via aryl hydrocarbon receptors (AHR) to increase transcription for mRNA for p450 enzymes. such as CYP1A2.