GI Drugs Flashcards
PPIs
Omeprazole , iansoprazole
Irreversibly binds to the H+/K+-ATPase
Prodrugs activated by the acidic environment
Indications: peptic ulcer disease, GORD, H. Pylori eradication, Zollinger–Ellison syndrome
Adverse effects: diarrhoea, headache, abdo pain, nausea, fatigue, dizziness
Warnings: may disguise gastric cancer
Administration: PO (once daily, best taken in the morning before food), or IV
Alginates and antacids
Gaviscon, Peptac, Mucogel
Act as buffers that increase pH of gastric juice and inactivate pepsin by this mechanism
Major indications: GORD, dyspepsia
Adverse effects: Mg or Al salts used alone can cause diarrhoea, avoided when used together
Warnings: if there is a high sodium or potassium content they should be used on a salt restricted diet
Administration: PO
H2 receptor antagonists
Ranitidine
Competitive antagonism of the H2 receptor on the basolateral membrane of acid secreting parietal cells of the gastric glands.
Indications: peptic ulcer disease, dyspepsia, GORD
Adverse effects: bowel disturbance, headache, abdominal pain, dizziness
Warnings: may disguise gastric cancer
Administration: PO twice daily
Antimuscarinic drugs
Hyoscine butylbromide
Competitive antagonist of muscarinic acetylcholine receptors, opposes the action of parasympathetics on the gut. Reduces spasm of smooth muscle, peristalsis, and glandular secretions
Indications: smooth muscle spasm in IBS, excessive respiratory secretions in palliative care
Adverse effects: tachycardia, dry mouth, constipation, urinary retention, blurred vision
Warnings: use with caution in patients at risk of cardiac arrhythmias
Administration: PO for IBS
Antimotility drugs
Loperamide, codeine phosphate
Opioid agonist active at enteric neurones of the GI tract. increases tone and rhythmic contractions, constricts smooth muscle sphincters, inhibits peristalsis.
Indications: treatment of acute diarrhoea, analgesia for acute or moderate pain
Adverse effects: constipation, abdo cramping, flatulence
CI: acute UC, acute bloody diarrhoea, C diff colitis
Administration: PO as capsule or tablet
Aminosalicylates
Mesalazine, balsalazide
5-ASA Carl’s locally to exert anti-inflammatory and immunosuppressant effects upon the colon.
Indications: first line for mild/moderate UC
Adverse effects: GI upset, headaches, rarely causes blood abnormalities
CI: avoid use in patient with aspirin hypersensitivity
Administration: PO
Bulk forming laxatives
Ispagula husk Hydrophilic agents (polysaccharide or cellulose) that are indigestible. By osmosis water is attracted, increasing the bulk
Indications: constipation, faecal impact ion, mild chronic diarrhoea associated with diverticular disease or IBS
Adverse effects: abdominal distension and flatulence, rarely may cause faecal impact ion
Administration: PO around meal times
Osmotic laxatives
Lactulose, macrogols, and phosphate or citrate enemas
Osmotically active agents that attract water to increase bulk
Indications: constipation, faecal impaction, bowel prep, hepatic encephalopathy
Adverse effects: abdo cramps, nausea, flatulence, diarrhoea, contraindicated in intestinal obstruction
Warning: Phosphate enemas may cause significant fluid shifts and should be used with caution in hear failure, ascites and when electrolyte disturbances are present.
Administration: PO with or without food, as enema as required but no more than uncle daily
Stimulant laxatives
Senna, bisocodyl, glycerol suppository, docusate sodium, sodium picosulfate
Increase electrolyte and water secretion from colonic mucosa.
Indications: constipation, faecal impaction
Adverse effects: abdo cramping, diarrhoea, prolonged use may result in irreversible atonic colon
Dopamine D2 receptor antagonists, antiemetic
Domperidone, metroclopramide
Antagonists of D2 receptors in the CTZ which is important in the detection of emetogenic substances in the blood
Indications: nausea and vomiting in a wide range of conditions, treatment of GORD
Adverse effects: most commonly diarrhoea. Metoclopramide may cause extrapyramidal syndromes including disorders of movement
CI: gastrointestinal obstruction and perforation
Administration: PO up to three times daily
Histamine H1 receptor antagonists, antiemetic
Cyclising, cinnarazine
Competitive antagonism of H1 receptors in the vomiting centre.
Indications: Nausea and vomiting in a wide range of conditions, particularly motion sickness, vertigo and post-operative nausea
Adverse effects: drowsiness, sedation
Warning: should be avoided in patients at risk of hepatic encephalopathy
Administration: PO regularly or as required
Phenothiazine, anti-emetics
Procloperazine
Involved in competitive antagonism of dopamine D2, histamine H1 and muscarinic M1 receptors in the vomiting centre
Indications: treatment of nausea and vomiting in a wide range of conditions particularly vertigo
Adverse effects: drowsiness and postural hypotension
CI: severe liver disease, prostatic hyperplasia
Administration: orally, or deep IM
5-HT3 receptor antagonists, antiemetic
Ondansetron
Competitive antagonisms of 5-HT3 receptors located in the CTZ, blocks 5-HT from stimulating vagal afferents that activate the vomiting centre
Indications: nausea and vomiting associated with chemo- and radio-therapy, IBS, hyperemesis gravidarum
Adverse effects: constipation, diarrhoea, headaches
CI: constipation, intestinal obstruction, stricture, toxic megfatcolon, ischaemic colitis, crohn’s disease, ulcerative colitis, diverticulitis
Administration: PO, PR, IM, or IV dependent upon the clinical indication
