Pharmocology

Question 1

what drugs are used for acid suppression?

Answer 1

> antacids
h2-receptor antagonists
proton pump inhibitors

Question 2

what drugs affect GI motility?

Answer 2

> anti-emetics
anti-muscarinics
anti-motility

Question 3

what drugs are used in inflammatory bowel disease?

Answer 3

> aminosalicylates
corticosteroids
immunosuppressants
biologics

Question 4

what drugs affect intestinal secretions?

Answer 4

> bile acid sequestrants

> ursodeoxycholic acid

Question 5

what metals do antacids contain?

Answer 5

magnesium or aluminium

Question 6

what is the action of antacids?

Answer 6

they neutralise gastric acid

Question 7

what is the action of alginates?

Answer 7

they form a viscous gel that floats on the stomach contents reducing reflux

Question 8

describe the action of H2-receptor antagonists

Answer 8

they block histamine (H2) receptor thereby reducing acid secretion

Question 9

when are h2-receptors indicated?

Answer 9

in GORD or peptic ulcer disease

unless patient cannot use proton pump inhibitor do not use a lot of them

Question 10

how are h2-receptor antagonists administered?

Answer 10

orally or intravenously

Question 11

when are proton pump inhibitors indicated?

Answer 11

in GORD or peptic ulcer disease

Question 12

how are proton pump inhibitors administered?

Answer 12

orally or intravenously

Question 13

what is triple therapy for treatment of PU/DU associated with?

Answer 13

H. Pylori

Question 14

what problems are associated with proton pump inhibitors?

Answer 14

> GI upset
predisposition to c. difficile infection
hypomagnesaemia
b12 deficiency

Question 15

what agents increase gut motility and gastric emptying?

Answer 15

prokinetic agents

Question 16

what is the mechanism of prokinetic agents?

Answer 16

it is not clear but involves parasympathetic control of smooth muscle and sphincter tone

Question 17

what is the action of domperidone?

Answer 17

it acts by blocking dopamine receptors which inhibit post synaptic cholinergic neurones

Question 18

what drugs work on the chemoreceptor trigger zone to stop vomiting?

Answer 18

> dopamine antagonists
5HT3 antagonists
cannabinoids

Question 19

what drugs act on the pharynx and GIT to stop vomiting?

Answer 19

> 5HT3 antagonists

> dopamine antagonists

Question 20

what drug acts on the vestibular nuclei to stop vomiting?

Answer 20

anti-histamines

Question 21

what drugs act on the vomiting centre in the medulla to stop vomiting?

Answer 21

> anti-muscarinics

> anti-histamines

Question 22

what is the mechanism of action of loperamide?

Answer 22

it acts on the opiate receptors in the GI tract to decrease ACh release. this decreases smooth muscle contraction and increases anal sphincter tone causing a decrease in motility.

Question 23

why does loperamide have few central opiate effects?

Answer 23

it is not well absorbed across the blood-brain barrier

Question 24

by what three mechanisms do antispasmoids reduce symptoms of IBS and renal colic?

Answer 24

> anti-cholinergic muscarinic antagonists (inhibit smooth muscle contraction in gut wall)
direct smooth muscle relaxants
calcium-channel blockers reduce calcium required for smooth muscle contraction

Question 25

what are the 4 types of laxatives?

Answer 25

> bulk > osmotic > stimulant > softeners

Question 26

what issues can there be with laxatives?

Answer 26

> obstruction (lead to perforation) > route of administration (oral or rectal) > other measures as oral laxative will not work without adequate fluid intake > misuse

Question 27

what is the action of aminosalicylates?

Answer 27

anti-inflammatory

Question 28

how are aminosalicylates administered?

Answer 28

orally or rectally

Question 29

when should you avoid prescribing aminosalicylates?

Answer 29

> in patients allergic to salicylates (as they are chemically related)

Question 30

when should you use caution in using aminosalicylates?

Answer 30

in renal impairment

Question 31

what are the adverse effects associated with aminosalicylates?

Answer 31

> GI upset > blood dyscrasias > renal impairment

Question 32

how are corticosteroids administered?

Answer 32

orally, IV or rectally

Question 33

what are contraindications for use of corticosteroids for IBD?

Answer 33

> osteoporosis | > cushingoid features including weight gain, DM, HT

Question 34

what concerns are there with using corticosteroids for IBD?

Answer 34

> there is increased susceptibility to infection | > addisonian crisis, with abrupt withdrawal (hypertensive, dehydrated)

Question 35

what is the action of immunosuppressants in IBD?

Answer 35

they prevent to formation of purines required for DNA synthesis so reduces immune cell proliferation

Question 36

what are the adverse effects associated with use of immunosupressants in IBD?

Answer 36

> bone marrow suppression > azathioprine hypersensitivity > organ damage > numerous drug interactions

Question 37

what is required when using immunosuppressant's in IBD?

Answer 37

specialist use and close monitoring

Question 38

what is infliximab?

Answer 38

a biologic, antiTNF(alpha)antibody. | mouse human chimeric antibody to TNF-alpha

Question 39

what do biologics prevent?

Answer 39

action of TNF alpha, key cytokine in inflammatory response

Question 40

what are the cautions/contraindications of infliximab?

Answer 40

> current TB (or other serious infection) > multiple sclerosis > pregnancy/breast feeding

Question 41

what are the adverse effects associated with infliximab?

Answer 41

``` > risk of infection (TB) > infusion reaction (fever, itch) > anaemia, thrombocytopenia, neutropenia > demyelination > malignancy ```

Question 42

name some biologics other than infliximab

Answer 42

> certolizumab > adalimumab > golimumab > vedolizumab

Question 43

what is certolizumab?

Answer 43

fab fragment of humanized anti-TNF alpha monoclonal antibody

Question 44

what is adalimumab?

Answer 44

humanized recombinant antibody to TNF

Question 45

what is natalizumab?

Answer 45

ant-integrin monoclonal antibody

Question 46

what is the action vedolizumab?

Answer 46

it binds to integrin alpha4beta7 (peyers patch adhesion molecule)

Question 47

what is the action of cholestyramine?

Answer 47

it reduces bile salts by binding with them in the gut so they are excreted as insoluble complex

Question 48

what may cholestyramine affect?

Answer 48

> absorption of other drugs | > fat soluble vitamin absorption (may decrease vitamin k levels affecting warfarin and clotting)

Question 49

what is ursodeoxycholic acid used to treat?

Answer 49

> gallstones | > primary biliary chirrhosis

Question 50

what is the action of ursodeoxycholic acid?

Answer 50

it inhibits enzymes involved in the formation of cholesterol altering the amount in bile and slowly dissolving non-calcifies stones

Question 51

what problems may there be with the ADME of GI pharmacology?

Answer 51

> GI/liver diseases can affect the processes of the drug ADME > GI symptoms also necessitate a change in route of administration

Question 52

what may affect the absorption of a drug?

Answer 52

> pH > gut length > transit time

Question 53

what may affect the distribution of a drug?

Answer 53

> low albumin (decreased binding leads to increased free drug concentration)

Question 54

what may effect the metabolism of a drug?

Answer 54

> liver enzymes > increased gut bacteria > gut wall metabolism > liver blood flow

Question 55

what may effect the excretion of a drug?

Answer 55

> biliary excretion

Question 56

what GI adverse effects can there be with medication?

Answer 56

> diarrhoea/constipation > GI bleeding/ulceration > changes to gut bacteria > drug induced liver injury

Question 57

what is 25% of all drug induced diarrhoea due to?

Answer 57

antimicrobials

Question 58

what are the effects of changes to gut bacteria?

Answer 58

> loss of OCP activity > reduced vitamin K absorption (increased prothrombin time) > overgrowth of pathogenic bacteria

Question 59

what type of ADR is intrinsic hepatotoxicity?

Answer 59

type a as it is predictable, dose dependent and acute

Question 60

what type of ADR is idiosyncratic hepatotoxicity?

Answer 60

type b as it is unpredictable, not dose dependent and can occur at anytime

Question 61

what are the effects of idiosyncratic hepatotoxicity?

Answer 61

they can range from asymptomatic increase in LFTs to fulminant liver failure and death

Question 62

what are the risk factors of hepatotoxicity?

Answer 62

``` > elderly > female > alcohol > genetic factors > malnourishment ```

Question 63

what classification is used when judging the severity of liver disease?

Answer 63

child-pugh classification

Question 64

what are the groups in the child-pugh classification?

Answer 64

``` A= <7 B= 7-9 C= >9 ```

Question 65

what things are scored in the child-pugh classification of liver disease?

Answer 65

``` > bilirubin > albumin > PT (prolonged) > encephalopathy > ascites ```

Question 66

when prescribing for liver disease what should you take care of/avoid?

Answer 66

> drugs that can be toxic due to changes in pharmacokinetics > drugs which are hepatotoxic > drugs which may worsen the non-liver aspects of liver disease

Question 67

what specific drugs should you avoid in liver disease?

Answer 67

> warfarin (clotting factors already low) > aspirin/NSAIDs (increases bleeding time, can worsen ascites) > opiates/ benzodiazepines (may precipitate encephalopathy)