Name Class Clinical Indications Receptor Action Mechanism of Action Adverse Effects and Interactions Administration + PK
Hypercholesterolemia Inhibits HMG-CoA reductase. HMG-CoA reductase usually takes part in the rate limiting step of cholesterol
Atorvastatin HMG-CoA reductase Diarrhoea,nausea, joint pain, insomnia, nasal Oral, extensive first pass
Statins Statin Hypertriglyceridemia synthesis. As it is inhibited less cholesterol is synthesised. This leads to decreased hepatic and serum
congestion, sore throat metabolism and low Vd
Simvastatin Combined dyslipidemia antagonist cholesterol. Also decreases triglycerides as cholesterol is essential for VLDL synthesis in the liver.
Losing weight and maintaining Gastric and pancreatic Antagonises the gastric and pancreatic lipase enzymes, this prevents the breakdown of triglycerides in the Steatorrhoea, flatus discharge, faecal urgency Oral, minimal absorption,
Lipase inhibitors Orlistat Lipase inhibitor weight loss body preventing their absorption. The triglycerides are excreted and dietary fat is lowered. and increased defecation low Vd
lipase antagonist
Antagonises M1 receptors. Activation of M1 receptors in the vestibular nuclei, solitary tract and the
Blurred vision, dry mouth, urinary retention and
Hyoscine Antimuscarinic Motion sickness M1 receptor antagonist vomiting centre directly activates the CNS pathways triggering nausea and vomiting. By blocking the M1
constipation
Oral or transdermal patch
receptors the pathways cannot be activated.
Antagonises D2 receptors in the chemoreceptor trigger zone, inhibiting the Gi second messenger
Domperidone Nausea and vomiting system. This blocks afferent signals that would usually travel to the vomiting centre. This decreases nausea
Metoclopramide Prokinetic Dysmotility dyspepsia D2 receptor antagonist and vomiting. Also increases motility throughout the entire GI tract, resulting in enhanced gastric emptying, Parkinsonism, tardive dyskinesia and dystonia Oral
Prochlorperazine Gastro-oesophageal reflux reduction in volume of acid and increased lower oesophageal sphincter basal tone due to the blocking of the
Gi second messenger system.
Antiemetics Antagonises 5-HT3 receptors in the intestinal vagal afferents, chemoreceptor trigger zone and
Granisetron Chemotherapy-induced nausea and 5-HT3 receptor Headache, dizziness and constipation
Antiemetic vomiting
vomiting centre. By blocking these afferent signals, it reduces the vomiting reflex produced by the vomiting
Can cause prolonged QT
Oral or IV prior to chemo
Ondansetron antagonists centre.
Motion sickness Binds to H1 receptors in their inactive state. This reduces receptor activity in the vestibular nuclei and
H1 receptor inverse Blurred vision, dry mouth, urinary retention,
Cyclizine Antiemetic Labyrinthitis vomiting centre. By blocking these receptors it reduces the vomiting reflex produced by the vomiting centre.
constipation, drowsiness and prolonged QT
Oral
Meniere's disease agonist
Prevention of chemotherapy-induced Antagonises NK1 receptors in the chemoreceptor trigger zone and vomiting centre. This blocks the Orally with dexamethasone
Aprepitant Antiemetic nausea and vomiting
NK1 receptor antagonist actions of substance P, preventing the activation of the vomiting reflex from the vomiting centre.
Fatigue and constipation
and a setron
Aluminium hydroxide Reacts with HCl to form water and a metal salt. This neutralises the acid and prevents symptoms of
Hydrochloric acid indigestion. Aluminium compounds cause constipation Oral liquid (more effective)
Antacids Magnesium carbonate Antacid Acid reflux and GORD
Magnesium compounds cause diarrhoea or tablets
neutralizer
Magnesium trisilicate
Binds to divalent cations such as Ca2+ forming a strong gel that floats on the surface of the stomach
Alginates Alginate Alginate Acid reflux and GORD Binds to divalent cations contents. This ‘raft’ suppresses the reflux and reduces symptoms of indigestion
Constipation Oral
Competitively antagonises H2 receptors in parietal cells in the stomach. This inhibits the Gs second
Gynecomastia, galactorrhoea, confusion in
GORD messenger system resulting in less conversion of ATP into cAMP. This results in less protein kinase. Protein
H2 antagonists Ranitidine H2 antagonist Gastric and duodenal ulcers
H2 receptor antagonist kinase is needed to activate the proton pumps on parietal cells. As a result of low protein kinase slowing the
elderly and CYP450 enzyme inhibition Orally in the evening
Cautions: Renal impairment
proton pumps, gastric acid secretion is reduced by ~70%.
Agonises prostaglandin E2 receptors in parietal cells in the stomach, stimulating the Gi second
Prostaglandin Prostaglandin GORD Prostaglandin E2 receptor messenger system. This decreases the conversion of ATP to cAMP. This results in less protein kinase.
Misoprostol Gastric and duodenal ulcers Protein kinase is needed to activate the proton pumps on parietal cells. As a result of low protein kinase
Nausea, vomiting and rash Oral
analogues analogue agonist
slowing the proton pumps, gastric acid secretion is decreased.
GORD Omeprazole freely crosses parietal cell membranes in it’s prodrug neutral form. It passes into the
Nausea, GI disturbance, diarrhoea, headache
Proton pump Gastric and duodenal ulcers canaliculus of the parietal cell where in the acidic conditions, it is converted to it’s active sulfenamide
Omeprazole Proton pump inhibitor Helicobacter pylori eradication in
H+/K+ ATPase inhibitor form. This forms a disulphide bond with H+/K+ ATPase, irreversibly inhibiting it, decreasing gastric acid
and increased risk of bone fracture with long Oral
inhibitors term use
combination with antibiotics secretion by 80-95%.
Agonises 𝝁 Opioid receptors in the myenteric plexus which results in the inhibition of ACh release to
Loperamide Anti-motility Diarrhoea 𝝁 Opioid receptor agonist gastric smooth muscle resulting in decreased motility and therefore faecal excretion
Abdominal pain, nausea and constipation Oral
Absorbs water in the intestinal lumen which dehydrates the stools, bulking them up, stopping the diarrhoea.
Anti-diarrhoeals Methylcellulose Adsorbent Diarrhoea Absorption of water Also absorbs intestinal microorganisms and coats the intestinal mucosa.
Stomach cramps and rectal bleeding Oral
Stimulates the absorption of electrolytes such as sodium and chloride ions from the intestinal lumen into the
Fluid transport Stimulation of electrolyte
Bismuth subsalicylate Diarrhoea interstitium. This absorption of electrolytes causes solvent drag, meaning water is absorbed too, dehydrating Abdominal pain, black stools, constipation Oral
modifier absorption the stools and decreasing diarrhoea.
