Gastrointestinal Drugs Flashcards
Give 3 examples of PPIs?
Omeprazole
Lansoprazole
Pantoprazole
What is the MoA for PPIs?
Bind to H+/K+ ATPase pump on gastric parietal cells
Reduces HCl production and hence reduced gastric acidity
What are the indications for a PPI?
Peptic ulcers Gastro-oesophageal reflux disease H.Pylori infection Prophylaxis in patients receiving long term NSAIDs Zollinger-Ellison syndrome
List some side effects of PPIs:
Nausea Vomiting Insomnia Vertigo Headaches
What is important clinically regarding pharmaco-kinetics/dynamics for PPIs?
Omeprazole is an inhibitor of cytochrome P450 enzymes
what info should be given to a patient before starting a PPI?
Avoid alcohol
Take 30-60mins before food
Give 4 examples of H2 receptor antagonists
Ranitidine
Cimetidine
Famotidine
Nizatidine
What is the MoA for H2 receptor antagonists?
Histamine binds to H2 receptors on gastric parietal cells stimulating gastric acid secretion
Drugs antagonise the effect of histamine at these H2 receptors
Reduced cAMP and hence reduced activity of H+/K+ ATPase pump
What are the indications for a H2 receptor antagonist?
Peptic ulcer
Gastro-oesophageal reflux disease
Zollinger-Ellison syndrome
List some side effects of H2 receptor antagonists:
Headache Dizziness Diarrhoea Reduced B12 absorption Gynaecomastia
What is important clinically regarding pharmaco-kinetics/dynamics for H2 receptor antagonists?
Cimetidine is an inhibitor of cytochrome P450 enzymes.
What info should be given to patient before starting a H2 receptor antagonist?
Avoid high protein diet
Take without regard to meals
What are 2 examples of laxatives?
lactulose
senna
what is the MoA for senna and lactulose?
Lactulose – reduces water reabsorption in intestine; it pulls water into the bowel and thus promotes distention and movement
Senna – stimulant / irritant agent
what are the indications for a laxative?
pregnancy
constipation
prophylaxis in opiate analgesic use
list some side effects of laxatives:
Dehydration
Salt loss
Abdominal cramps
Fatigue
What is important clinically regarding pharmaco-kinetics/dynamics for laxatives?
Lactulose - consists of monosaccharides: fructose and galactose. Breakdown of this in the intestine by colonic bacteria increases osmotic pressure
Senna - recommended for short term use only. Risk of organ failure with long term use or abuse.
What info should be given to patient before starting a laxative?
take liberally without regard to meals
give examples of the different types of laxatives:
Bulk producing agent – adds more substance so that they can pass through intestine easily (lactulose)
Stool softeners – adds more water and fat into the stool
Stimulant or irritant – acts on intestinal mucosa and alters water and electrolyte secretion (senna)
Hydrating agents – intestines hold more water (milk of magnesia)
what is the MoA forCyclizine?
Histamine H1 receptor antagonist
Acts on vomiting center in the medullary region
Mild anti-cholinergic and anbti-muscarinic effects
what are the indications for Cyclizine?
Nausea and vomiting
Motion sickness
Vertigo and dizziness
Prophylaxis alongside chemotherapy and opiate analgesic use
List some side effects of Cyclizine:
Headache
Sedation
Diarrhoea
What is important clinically regarding pharmaco-kinetics/dynamics for Cyclizine?
It can also be a central nervous system depressant
what info should be given to the patient before starting Cyclizine?
Avoid alcohol
Food may reduce irritation
Take without regard to meals
Give 5 examples of the different types of anti-emetics
Anti-cholinergics (Hyoscine hydrobromide)
Blocks acetylcholine neurotransmitters in the CNS and the PNS
Anti-histamines (Cyclizine)
H1 histamine receptor antagonist
Serotonin antagonists (Ondansetron) Block serotonin receptors in the CNS and the GIT
Phenothiazines (Prochlorperazine)
Dopamine receptor antagonist (D2 receptor antagonist)
Motility stimulants (Metoclorpramide) Dopamine receptor antagonist (D2 receptor antagonist)
What is the MoA for metoclopramide?
Dopamine (D2) receptor antagonist
Raises activity in the chemoreceptor trigger zone – reducing input from afferent visceral nerves
Also increases gastric emptying and intestinal transit
Reduced oesophageal reflux
what are the indications for metoclopramide?
Nausea
Vomiting
To increase gastric emptying
list the side effects of metoclopramide:
Dystonia (due to dopamine antagonism) Confusion Dizziness Diarrhoea Parkinsonism with long term use
What is important clinically regarding pharmaco-kinetics/dynamics for metoclopramide?
Can be given orally or parenterally
Dystonic reactions and movement disorders are more common at the extremes of age so caution is needed in these groups
what info should be given to patient before starting metoclopramide?
avoid alcohol
Take 30 mins before meal
what is the MoA for Prochlorperazine?
Penothiazine anti-psychotic drug used as an anti-emetic
Dopamine (D2) receptor antagonist
Causes increased dopamine turnover (in mesolimbic and chemoreceptor trigger zone)
what are the indications for Prochlorperazine?
Nausea and vomiting
Used as an adjunct in some psychotic disorders
what are the side effects of Prochlorperazine?
Dry mouth
Tachycardia
Restlessness
Drowsiness
What is important clinically regarding pharmaco-kinetics/dynamics for Prochlorperazine?
Anticholinergic and alpha-adrenergic receptors antagonism occurs leading to; sedation, muscle relaxation, and hypotension.
The dose differs substantially when given parenterally
what info should be given to patient before starting Prochlorperazine?
Avoid alcohol and caffeine
Take with food along with a full glass of water
