Pharma basis for treatment

Question 1

What are the effects of metoclopramide and what does this inhibit?

Answer 1

Inhibits pre and post synaptic dopamine(D2) receptors and 5-HT3(CNS) receptors
Also stimulates 5-HT4(ENS)
–This inhibits vomiting

Question 2

What are the effects of inhibition of dopamine at D2 receptors by metoclopromide?

Answer 2

1. There is increased release of Ach, which leads to increased peristalsis of duodenum, jejunum and ileum
2. The increased Ach results in an increase in intragastric pressure. This is due to increased LOS tone and increase in tone of gastric contractions
   -These improve antroduodenal coordination which accelerates gastric emptying

Question 3

What are prokinetic effects of metoclopromide?

Answer 3

Stimulates excitatory 5-HT receptors and inhibitory nitrigeric neurons
-Results in coordinated gastric motility

Question 4

What can metoclopramide impact via central effects?

Answer 4

-Antiemetic properties
-Relieves headaches

Question 5

What is metoclopramide useful for?

Answer 5

1. Gastrointestinal reflux
2. Stimulates gastric motility
3. Accelerates gastric emptying

Question 6

What do antispasmodic agents do?

Answer 6

↓ spasm in bowel. They have relaxant action on GIT (relax smooth muscle in GIT)

Question 7

What type of agent is propantheline?

Answer 7

Antimuscarinic agent

Question 8

What do muscarinic receptor antagonists inhibit and what does this reduce?

Answer 8

inhibit parasympathetic activity. This reduces
spasm in the bowel Jejunal diverticular

Question 9

What are the causes of constipation?

Answer 9

↓ motility of large intestine
– Old age
– Damage to enteric nervous system of colon (-may affect the initiation of vago-vagal reflex)

Question 10

What are factors that can increase colonic motility?

Answer 10

• ↑ fibre, cellulose and complex polysaccharides
• Bran, some fruits and vegetables with high fibre
• Laxatives, but excessive use → ↓ responsiveness
• Mineral oil – lubricates faeces
• Castor oil – stimulates motility of colon

Question 11

What can purgatives?

Answer 11

Purgatives can modulate/hasten food transit in the
intestine
* Laxatives, faecal softeners & stimulant

Question 12

What are examples of bulk laxatives?

Answer 12

Methylcellulose

Question 13

What are examples of bulk-forming and osmotic laxatives?

Answer 13

Increase the weight of the stool by absorbing water → promotion of peristalsis

Question 14

What are the side effects of purgatives?

Answer 14

-Bloating
-Flatulence

Question 15

What does lactulose do to combat constipation?

Answer 15

• ↑ and maintains volume of fluid in the lumen of bowel by osmosis
• ↑ transfer of gut contents into the intestine
• Increases volume of gut content entering the colon → distension and
  purgation in 1hr

Question 16

What do high doses of lactulose cause?

Answer 16

flatulence, cramps, diarrhoea, vomiting and tolerance

Question 17

What is a summary of the mode of action of lactulose?

Answer 17

Unchanged lactulose reaches the colon –> Colonic bacteria breaks it down into short chain fatty acids–>Osmotic pressure increases and biomass increases–>Softening of faeces/volume of stool increases–>Peristalsis is stimulated–>Colonic transit time is shortened

Question 18

What are the causes of diarrhoea?

Answer 18

• Infectious agents
• Toxins
• Anxiety
• Drugs

Question 19

what happens in acute diarrhoeal diseases?

Answer 19

Diarrhoea → ↑ motility of GIT, with ↑ secretion and ↓ absorption of fluid → ↓ electrolyte (Na+) and H2O

Question 20

What do antidiarrhoeal drugs do to movement?

Answer 20

↓ movement

Question 21

What do antispasmodic drugs do to movement?

Answer 21

↓ movement; relax smooth muscles in GIT

Question 22

What needs to be maintained in diarrhoea treatment?

Answer 22

Maintain fluid and electrolyte balance: Oral rehydration therapy

Question 23

What bacteria causes gastroenteritis in the UK?

Answer 23

Campylobacter sp: cause of gastroenteritis in the UK

Question 24

What can be used if diarrhoea is viral in nature?

Answer 24

-Use anti-motility drugs
-adsorbents and agents that modify fluid and
electrolyte transport

Question 25

What is loperamide used for and how does it work?

Answer 25

-Selective on GIT
-Decreases passage of faeces

Question 26

What action does codeine and loperamide have and what does it do to GIT motility?

Answer 26

Anti-secretory action;
* ↓ intestinal motility

Question 27

What does bismuth subsalicylate decrease?

Answer 27

Decreases fluid secretion in bowel

Question 28

Who is bismuth subsalicylate safe for in children?

Answer 28

Safe for children over 12, but not if they have chicken pox, flu

Question 29

What are the side effects of bismuth subsalicylate?

Answer 29

May cause tinnitus and blackening of stool

Question 30

What type of agonist is loperamide?

Answer 30

An opioid receptor agonist

Question 31

What receptor does loperamide bind to and where?

Answer 31

Binds to the μ-opioid receptor of the myenteric plexus of the large intestine

Question 32

What happens when the μ- opiod receptor is stimulated by loperamide?

Answer 32

Stimulation of the μ-opioid receptor by loperamide inhibits gastric
emptying, increases sphincter tone, induces stationary motor patterns
and blocks peristalsis

Question 33

What type of agent is loperamide and what does it do?

Answer 33

A spasmolytic agent which reduces smooth muscle activity in the GIT and
thus reduces the passage of faeces

Question 34

How does loperamide reduce force and speed of clonic movement?

Answer 34

• Increases haustral mixing of the proximal colon
• Inhibits propulsive mass movement of the distal colon