What is a common cause of peptic ulceration with fever? What is the common treatment for this?
H. Pylori PPI (omeprazole). Abx (amxoicillin, metronidazole).
What 2 elements protect the stomach lining from acid and how do they work?
The mucous barrier is a thick matrix of mucus into which is secreted bicarbonate ions, acting a a buffer. The surface epithelium, which has a cytoprotective action through prostaglandins E2 and I2.
Which gastric cells secrete acid? How is acid secretion controlled? Describe the process of secretion.
Parietal cells. Stimulation of gastrin receptors by gastrin from G cells, H2 receptors by histamine from enterochromaffin-like paracrine cells or M1 receptors by ACh from neurones stimulates acid secretion. Enterochromaffin-like paracrine cells are also stimulated by gastrin and ACh from the vagus nerve. These factors activate adenylyl cyclase in the parietal calls causing cAMP production. This causes proton pumps to remove K+ from the lumen in exchange for H+, and this droves K+ Cl- symport into the lumen creating HCl.
What is Zollinger-Ellison syndrome?
Peptic ulceration caused by increased gastrin production from a gastrinoma.
What are 2 common causes of GORD? What are 3 precipitating factors of GORD? What are the 4 escalating steps in the treatment of GORD?
Loss of lower oesophageal sphincter tone and increased intra-abdominal pressure. Overweight, smoking, alcohol. Lifestyle changes, H2-receptor antagonists, PPIs, anti-reflux surgery.
Give 2 examples of PPIs. What is their mechanism of action? 5 indications? 3 ADRs?
Omeprazole, lansoprazole. MoA - Irreversible binding to and inhibition of H+/K+ ATPase. Indications - Peptic ulcers, H. Pylori, Zollinger-Ellison, severe GORD, oesophagitis. No contraindications. ADRs - GI upset, headaches, gastric atrophy (long term treatment)
Give 2 examples of H2 agonists. What is their mechanism of action? Name 2 indications. Contraindications? ADRs?
Cimetidine, ranitidine. MoA - Competitive inhibition of H2-receptor agonists on parietal cells. Indications - Peptic ulcer, GORD Contraindications - Warferin, phenytonin, theophylline. ADRs - Dizziness, rash, gynecomastia, fatigue.
Give 1 example of a mucosal strengtheners. What is its mechanism of action? What class of drugs would be used alongside misoprostol? Name 2 indications. Contraindications? ADRs?
Misoprostol. MoA - Misoprostol is a prostaglandin E analogue promoting integrity and healing in the mucosal barrier. Indications - Ulcer healing and ulcer prophylaxis. Used with - NSAIDs. Contraindications - hypotension, pregnancy, breastfeeding. ADRs - diarrhoea, abdo pain.
Give 2 examples of antacids. What is their mechanism of action? 3 indications? 1 contraindication? 2 ADRs?
Aluminium hydroxide, magnesium hydroxide. MoA - Antacids contain alkaline salts which neutralise stomach acid, raising GI pH. Indications - relief of ulcer symptoms, non-ulcer dyspepsia, GORD. Contraindications - hypophosphataemia. ADRs - constipation, diarrhoea.
What 4 categories of antiemetics are there?
H1-receptor antagonists. Phenothiazines. Dopamine antagonists. 5-HT3 receptor antagonists.
Give 2 examples of H1 antagonist antiemetics. 3 indications? 3 ADRs?
Cyclizine, cinnarizine. Indications - Motion sickness, vestibular disorders, vertigo. Contraindications - prostatic hypertension, urinary retention and glaucome (due to high antimuscarinic activity). ADRs - Drowsiness, dry mouth, blurred vision.
Name the 9 most common causes of nausea and vomiting.
GI irritation. Motion sickness. Vestibular disease. Hormone disturbance. Drugs/radiation. Exogenous toxins. Pain. Psychogenic factors. Intracranial pathology.
How is the act of vomiting co-ordinated?
The chemoreceptor trigger zone (CTZ) lies outside the blood-brain barrier and detects stimuli including exogenous and endogenous chemicals and dopamine. Signals are sent to the vomiting centre within the brainstem along with signals from other nerve fibres to cause emesis.
Give 1 example of phenothiazine antiemetics. What other use does this class have? What is their mechanism of action? 3 indications? 1 contraindication? 4 ADRs?
Prochlorperazine. Antipsychotic medicaiton. MoA - Blocking dopamine, histamine and muscarinic receptors. Indications - Nausea and vomiting, vertigo, psychosis. Contraindications - Parkinsonian symptoms (exacerbates them as antidopaminergic). ADRs - Sedation, postural hypotension, increased prolactin, extrapyramidal effection
Give 2 examples of dopamine antagonist antiemetics. What is their mechanism of action? 2 indications? 1 contraindication? 2 ADRs?
Domperidone, metoclopramide. MoA - Blocking dopamine receptors in the CTZ and promoting gastric emptying and peristalsis. Indications - Nausea and vomiting, functional dyspepsia. Contraindications - age > 20 due to increased risk of extrapyramidal side effects. ADRs - Extrapyramidal effects, hyperprolactinaemia.
Give 1 example of 5-HT3 antagonist antiemetics. What is their mechanism of action? 1 indication? 2 ADRs?
Ondansetron. MoA - Antagonism of the 5-HT3 serotonin receptors in the CTZ. Indications - Nausea and vomiting. ADRs - Constipation, headaches.