GI Drugs Flashcards
Give 3 examples of PPIs.
Omeprazole
Lansoprazole
Pantoprazole
Describe the mechanism of action of PPIs. (2)
- Bind to the H+/K+ ATPase pump on gastric parietal cells
- Reduces HCl production
a. Therefore decreases gastric acidity
List 5 indications for PPIs.
Peptic ulcers Gastro-oesophageal reflux disease (GORD) H. pylori infection Prophylaxis in long term NSAID use Zollinger Ellison syndrome
List 5 side effects of PPIs.
Nausea Vomiting Insomnia Vertigo Headaches
Describe the important pharmacokinetics/dynamics of PPIs. (1)
What would you tell the patient when prescribing them? (2)
PHARMA:
Omeprazole is a cytochrome P450
PATIENT INFO:
Avoid alcohol
Take 30-60 mins before food
Give 4 examples of H2 receptor antagonists.
Ranitidine
Cimetidine
Famotidine
Nizatidine
Describe the mechanism of action of H2 receptor antagonists. (2)
- Histamine binds to H2 receptors on gastric parietal cells, which stimulates gastric acid secretion
- H2 receptor antagonists block the H2 receptor
a. This causes reduced cAMP levels
b. This causes reduced activity of the H+/K+ ATPase pump
List 3 indications for H2 receptor antagonists.
Peptic ulcer
Gastro-oesophageal reflux disease (GORD)
Zollinger Ellison syndrome
List 5 side effects of H2 receptor antagonists.
Headache Dizziness Diarrhoea Reduced B12 absorption Gynaecomastia
Describe the important pharmacokinetics/dynamics of H2 receptor antagonists. (1)
What would you tell the patient when prescribing these? (2)
PHARMA:
Cimetidine is a CYP450 inhibitor
PATIENT INFO:
Avoid high protein diet
Take without regard to meals
Give 2 examples of laxatives.
Lactulose
Senna
Describe the mechanism of action of 2 types of laxatives. Consider:
a) Lactulose (2)
b) Senna (1)
LACTULOSE:
1. Reduces water reabsorption in intestine
- Pulls water into bowel
a. This promotes distension and bowel movement
SENNA:
1. Stimulant/irritant agent
List 3 indications for laxatives.
Constipation
Pregnancy
Prophylaxis in opiate analgesic use
List 4 side effects of laxatives.
Dehydration
Salt loss
Abdominal cramps
Fatigue
Describe the important pharmakinetics/dynamics of lactulose. (2)
Same for senna. (2)
LACTULOSE:
Consists of monosaccharides (fructose and galactose)
Colonic bacteria break this down to create osmotic pressure
SENNA
Short term use only
Risk of organ failure with long term use/abuse
What would you tell the patient when prescribing laxatives? (1)
Take liberally without regard to meals
List the 4 types of laxative.
Bulk producing agent (lactulose)
Stool softeners
Stimulant or irritant (senna)
Hydrating agents (milk of magnesia)
What are the 3 main anti-emetic drugs?
Cyclizine
Metoclopramide
Prochlorperazine
Describe the mechanism of action of cyclizine. (3)
- Histamine H1 receptor antagonist
- Acts on the vomiting center in the medullary region
- Mild anti-cholinergic and anti-muscarinic effects
List 4 indications for cyclizine.
Nausea and vomiting
Motion sickness
Vertigo and dizziness
Prophylaxis with chemotherapy and opiates
List 3 side effects of cyclizine.
Headache
Sedation
Diarrhoea
Describe the important pharmacokinetics/dynamics of cyclizine. (1)
What would you tell the patient when prescribing this? (3)
PHARMA:
Can also be a CNS depressant
PATIENT INFO:
Avoid alcohol
Food may reduce irritation
Take without regard to meals
What are the 5 types of anti-emetics?
Give an example of each.
Anti-cholinergics (Hyoscine hydrobromide)
Anti-histamines (cyclizine)
Serotonin antagonists (ondansetron)
Phenothiazines (prochlorperazine)
Motility stimulants (metoclopramide)
Describe the mechanism of action of metoclopramide. (4)
- Dopamine (D2) receptor antagonist (a motility stimulant)
- Raises activity in the chemoreceptor trigger zone
a. This reduces input from afferent visceral nerves - Also increases gastric emptying and intestinal transit
- Also causes reduced oesphageal reflux
List 3 indications for metaclopramide.
Nausea
Vomiting
To increase gastric emptying
List 5 side effects of metaclopramide.
Dystonia Confusion Dizziness Diarrhoea Parkinsonism with long term use
Describe the important pharmacokinetics/dynamics of metaclopramide. (2)
What would you tell the patient when prescribing? (2)
PHARMA:
Admin: oral or parenteral
Dystonia/movement disorders are more common at the extremes of age
PATIENT INFO:
Avoid alcohol
Take 30 mins before meals
Describe the mechanism of action of prochlorperazine. (2)
- A type of penothiazine anti-psychotic used as an anti-emetic
- Dopamine (D2) receptor antagonist
a. Causes increased dopamine turnover (in the mesolimbic and chemoreceptor trigger zone)
List 2 indications for prochlorperazine.
Nausea and vomiting
Adjunct in some psychotic disorders
List 4 side effects of prochlorperazine.
Dry mouth
Tachycardia
Restlessness
Drowsiness
Describe the important pharmacokinetics/dynamics of prochlorperazine. (2)
What would you tell the patient when prescribing it? (2)
PHARMA:
Sedation, muscle relaxation and hypotension caused by anticholinergic/anti-alpha-adrenergic effects
PATIENT INFO:
Avoid alcohol/caffeine
Take with food and a full glass of water
