Drug therapies for gastrointestinal disorders Flashcards
What part of the brain stem is responsible for the emetic effect (being sick)?
Medulla oblongata
There is a ‘vomiting centre’ that contains muscurinic receptors, when stimulated triggers vomitting.
What is the chemoreceptor trigger zone and where is it?
Close to the medulla oblongata, outside the BBB
Triggered by chemicals
Have dopamine and serotonin receptors
What are PPI’s (proton pump inhibitors) used for?
Acid reflux, heartburn, prevent and treat peptic ulcers
Oral or IV meds
What are the suffix for PPI medications?
“-prazole”
E.g:
Omeprazole
Dexlansoprazole
Lansoprazole
Pantoprazole
How do proton pump inhibitors work?
Reduce the amount of stomach acid being produced.
What cells in our stomach are responsible for the production and release of stomach acid?
Parietal cells
What stimulates the parietal cells in the stomach and what happens when they are stimulated?
Gastrin, Histamine, Acetylcholine.
The parietal cells release protons into the stomach via the proton pump.
What does the proton pump do?
-Acts to move protons in the stomach.
-Move potassium into the parietal cells
These protons combine with chloride ions to form hydrochloric acid.
How are PPI’s activated?
By the acidic environment of our stomach.
What do PPI’s do?
Bind to the proton pump, inhibiting the proton production therefore reducing the HCL volume and the acidity of the stomach.
How long does it take PPI’s to reach maximum effect?
2-3 days.
How long do the affects of each does of a PPI last?
Approximately 1-2 days
Why shouldn’t pts suddenly discontinue the usage of PPI’s?
There is a risk of rebound affect (increased acid reflux)
Make sure pt gradually starts coming off meds.
What are the side effects of short term PPI usage?
Headaches
Diarrhoea
Abdominal pain
Nausea
What are the long term side effects of PPI usage? (1% risks)
- C.diff infections - pneumonia, fevers, diarrhoea - this is because low stomach acid will reduce immune function.
- Deficiency of Vitamins B12, Mg, Fe, Ca - this is because low stomach acid means low nutrient absorption; leading to osteoporosis and hip fractures.
What are antacids?
Ant = Against Acid = Acid
What is the mechanism of action for antacids?
Antacids work as a base to neutralise any excess hydrochloric acid.
What are the medication names and suffixes of antacids?
Suffix = carbonate or hydroxide
E.g:
Sodium bicarbonate
Calcium carbonate
Aluminum hydroxide
Magnesium hydroxide
What requires the usage of antacids?
Acid reflux
Peptic ulcers
What are the side effects of antacids?
Calcium and Aluminium meds cause ConstipAtion.
Magnesium meds cause GI upset and diarrhoea
What are the two types of stool softening laxatives?
Docusate sodium
Docusate calcium
How do laxatives work?
They draw water into the stool, which helps soften the stool.
What are the side effects of laxatives?
Mild cramping
Diarrhoea
What are the two types of bulk forming laxatives?
Psyllium
Methylcellulose
Used for constipation and chronic diarrhoea
What is the mode of action of bulk forming laxatives?
Combine with water in intestines to soften stool and increase the bulk of the stool.
What are the two types of stimulating laxatives?
Bisacodyl
Sennosides
What is the mode of action for osmotic laxatives?
They work by drawing water into the intestine
