Gastrointestinal Drugs Flashcards
What class of drug is Omeprazole (Losec)?
Proton pump inhibitor
What class of drug is Esomeprazole (Nexium)?
Proton pump inhibitor
What class of drug is Pantoprazole (Somac)?
Proton pump inhibitor
What class of drug is Rabeprazole (Pariet)?
Proton pump inhibitor
What class of drug is Ranitidine (Zantac)?
H2 receptor antagonist
What class of drug is Magnesium hydroxide (Mylanta/Milk of magnesia)?
Antacid
What class of drug is Misoprostol (Cytotec)?
Prostaglandin analogue
What class of drug is Hyoscine butylbromide (Buscopan)?
Anticholinergic (anti-muscarinic)
What class of drug is Mebeverine (Colofac)?
Spasmolytic
What class of drug is Bisacodyl (Bisalax)?
Stimulant laxative
What class of drug is Hysoscine hydrobromide (Kwells tablets/Travacalm)?
Anticholinergic (anti-muscarinic)
What class of drug is Metoclopramide (Maxolon)?
Dopamine receptor antagonist/ 5-HT3 receptor antagonist
What class of drug is Ondansetron (Zofran)?
5-HT3 receptor antagonist
What class of drug is Docusate (Coloxyl)?
Laxative (stool softener)
What class of drug is Loperamide (Imodium)?
Opioid antidiarrhoeal
What class of drug is Simethicone (De-Gas)?
Anti-foaming agent
What class of drug is Orlistat (Xenical)?
Anti-obesity drug
What class of drug is Phentermine (Duromine)?
Anti-obesity drug
What is the mechanism of action of Omeprazole (Losec)?
Irreversibly inactivates the hydrogen/potassium ATPase enzyme system (proton pump), suppressing both stimulated and basal acid secretion
When PPIs are stopped, acid secretion is restored by synthesis of new hydrogen/potassium ATPase
What is the mechanism of action of Esomeprazole (Nexium)?
Irreversibly inactivates the hydrogen/potassium ATPase enzyme system (proton pump), suppressing both stimulated and basal acid secretion
When PPIs are stopped, acid secretion is restored by synthesis of new hydrogen/potassium ATPase
What is the mechanism of action of Pantoprazole (Somac)?
Irreversibly inactivates the hydrogen/potassium ATPase enzyme system (proton pump), suppressing both stimulated and basal acid secretion
When PPIs are stopped, acid secretion is restored by synthesis of new hydrogen/potassium ATPase
What is the mechanism of action of Rabeprazole (Pariet)?
Irreversibly inactivates the hydrogen/potassium ATPase enzyme system (proton pump), suppressing both stimulated and basal acid secretion
When PPIs are stopped, acid secretion is restored by synthesis of new hydrogen/potassium ATPase
What is the mechanism of action of Ranitidine (Zantac)?
Competitively blocks H2 receptors on parietal cells, reducing gastric acid secretion
What is the mechanism of action of Magnesium hydroxide (Mylanta/Milk of magnesia)?
Neutralises or reduces gastric acidity, resulting in an increase in the pH of the stomach and duodenal bulb and inhibition of the proteolytic activity of pepsin
What is the mechanism of action of Misoprostol (Cytotec)?
Prostaglandin E1 analogue that protects GI mucosa by increasing the secretion of mucus in the stomach and stimulating bicarbonate secretion in the duodenum
Inhibits basal and stimulated acid secretion by a direct action on gastric parietal cells
What is the mechanism of action of Hyoscine butylbromide (Buscopan)?
Smooth muscle relaxant; reduces GI motility and spasm
What is the mechanism of action of Mebeverine (Colofac)?
Direct acting smooth muscle relaxant; reduces GI motility and spasm
No anticholinergic effects
What is the mechanism of action of Bisacodyl (Bisalax)?
Acts by direct stimulation of nerve endings in colonic mucosa to increase intestinal motility
May also cause accumulation of water and electrolytes in the colonic lumen
What is the mechanism of action of Hysoscine hydrobromide (Kwells tablets/Travacalm)?
Acts as a competitive antagonist at muscarinic acetylcholine receptors, specifically M1 receptors
What is the mechanism of action of Metoclopramide (Maxolon)?
The antiemetic action of metoclopramide is due to its antagonist activity at D2 receptors in the CTZ (chemoreceptor trigger zone) — this action prevents nausea and vomiting triggered by most stimuli
At higher doses, 5-HT3 antagonist activity may also contribute to the antiemetic effect
At increased doses, it acts on 5-HT3 and 5-HT4 receptors in the gut as a pro-motility drug to stimulate gastric emptying
However, as it is selective for the upper GIT, it does not cause diarrhoea
What is the mechanism of action of Ondansetron (Zofran)?
Central and peripheral 5HT3 receptor blockade
Acts on both CTZ (chemoreceptor trigger zone) and in GIT
What is the mechanism of action of Docusate (Coloxyl)?
Softens stool by assisting mixture of water into faeces
May also increase intestinal fluid secretion
What is the mechanism of action of Loperamide (Imodium)?
Opioid-receptor agonist which acts on the μ-opioid receptors in the myenteric plexus of the large intestine; by itself it does not affect the CNS
It works similarly to morphine, by decreasing the activity of the myenteric plexus, which in turn decreases the tone of the longitudinal and circular smooth muscles of the intestinal wall. This increases the amount of time substances stay in the intestine, allowing for more water to be absorbed out of the faecal matter
Loperamide also decreases colonic mass movements and suppresses the gastrocolic reflex
What is the mechanism of action of Simethicone (De-Gas)?
Anti-foaming agent that decreases the surface tension of gas bubbles, causing them to combine into larger bubbles in the stomach that can be passed more easily
Simethicone does not reduce or prevent the formation of gas in the digestive tract, rather, it increases the rate at which it exits the body
However, simethicone can relieve pain caused by gas in the intestines by decreasing foaming, which then allows for easier passing of flatulence
What is the mechanism of action of Orlistat (Xenical)?
Inhibits GI lipases, preventing absorption of approximately 30% of dietary fat
What is the mechanism of action of Phentermine (Duromine)?
Sympathomimetic with CNS stimulatory effects, increasing energy expenditure.
Increases NA (mainly), dopamine and 5-HT available to bind to receptors
What are the side effects of Omeprazole (Losec)?
- Headache
- Nausea
- Vomiting
- Diarrhoea
- Abdominal pain
- Constipation
- Flatulence
What are the side effects of Esomeprazole (Nexium)?
- Headache
- Nausea
- Vomiting
- Diarrhoea
- Abdominal pain
- Constipation
- Flatulence
What are the side effects of Pantoprazole (Somac)?
- Headache
- Nausea
- Vomiting
- Diarrhoea
- Abdominal pain
- Constipation
- Flatulence
What are the side effects of Rabeprazole (Pariet)?
- Headache
- Nausea
- Vomiting
- Diarrhoea
- Abdominal pain
- Constipation
- Flatulence
- Rhinitis
- Pharyngitis
- Cough
What are the side effects of Ranitidine (Zantac)?
- Bradyarrhythmia (following rapid IV administration)
- Hypotension
- Headache
- Tiredness
- Dizziness
- Confusion
What are the side effects of Magnesium hydroxide (Mylanta/Milk of magnesia)?
- Dizziness
- Fainting
- Sweating
- Diarrhoea
- Nausea
- Perianal irritation
- Hypermagnesia
What are the side effects of Misoprostol (Cytotec)?
- Diarrhoea
- Abdominal pain
- Nausea
- Flatulence
- Dyspepsia
- Vomiting
- Rash
- Headache
- Dizziness
- Constipation
- Uterine cramps
- Heavy uterine bleeding
- Intermenstrual bleeding
What are the side effects of Hyoscine butylbromide (Buscopan)?
- Dry mouth
- Tachycardia
- Reduced sweating
- Rash
- Itching
- Redness of skin
- Dysuria
What are the side effects of Mebeverine (Colofac)?
- Dyspepsia
- Anorexia
- Constipation
- Dizziness
- Insomnia
- Headache
- Bradycardia
- Malaise
- Allergic reactions
What are the side effects of Bisacodyl (Bisalax)?
- Rectal irritation
- Proctitis
- Diarrhoea
- Fluid and electrolyte imbalance
- Abdominal discomfort
- Cramps
- Nausea
What are the side effects of Hysoscine hydrobromide (Kwells tablets/Travacalm)?
- Dry mouth
- Dyshidrosis (inability to sweat)
- Tachycardia
- Bradycardia (at higher doses)
- Urticaria
- Pruritis
- Constipation
What are the side effects of Metoclopramide (Maxolon)?
- Akathisia (feeling of restlessness)
- Drowsiness
- Dizziness
- Headache
- Tardive dyskinesia
What are the side effects of Ondansetron (Zofran)?
- Constipation
- Headache
- Dizziness
- Transient rise in hepatic aminotransferases
- Transient visual disturbances
What are the side effects of Docusate (Coloxyl)?
- Abdominal cramps
- Diarrhoea
- Nausea
- Rash
What are the side effects of Loperamide (Imodium)?
- Abdominal pain and bloating
- Nausea
- Vomiting
- Constipation
- Paralytic ileus (bowel obstruction)
- Dizziness
- Rash
What are the side effects of Simethicone (De-Gas)?
- Mild diarrhoea
- Nausea
- Regurgitation
- Vomiting
What are the side effects of Orlistat (Xenical)?
- Flatus
- Steatorrhoea
- Faecal urgency/incontinence
- Headache
- Fatigue
- Hepatitis
- Pancreatitis
What are the side effects of Phentermine (Duromine)?
- Insomnia
- Restlessness
- Nervousness
- Euphoria
- Agitation
- Arrhythmia
- Tachycardia
- Hypertension
- Diarrhoea
- Vomiting
- Headache
- Rash
- Urinary frequency
- Facial oedema
- Unpleasant taste
- Urticaria
- Impotence
What are the indications for use of Omeprazole (Losec)?
Administration: oral tablet, capsule, injection (IV)
- PUD
- GORD
- Zollinger-Ellison syndrome
- H. pylori eradication
- Treatment and prevention of peptic ulcer and erosion associated with NSAIDs
Contraindications: Gastric carcinoma
What are the indications for use of Esomeprazole (Nexium)?
Administration: oral tablet, capsule, injection (IV)
- GORD
- Zollinger-Ellison syndrome
- H. pylori eradication
- Treatment and prevention of peptic ulcer and erosion associated with NSAIDs
- Prevention of peptic ulcer rebleeding
- Combination treatment with high-dose NSAID (e.g. rheumatoid arthritis)
Contraindications: Gastric carcinoma
What are the indications for use of Pantoprazole (Somac)?
Administration: oral tablet, granule, injection (IV)
- PUD
- GORD
- Zollinger-Ellison syndrome
- H. pylori eradication
- Prevention of dyspepsia, peptic ulcer and erosions associated with NSAIDs in people at increased risk who need continuous nonselective NSAID treatment
Contraindications:
Gastric carcinoma
What are the indications for use of Rabeprazole (Pariet)?
Administration: oral tablet
- PUD
- GORD
- H. pylori eradication
Contraindications: Gastric carcinoma
What are the indications for use of Ranitidine (Zantac)?
Administration: oral tablet, liquid, injection (IV)
- PUD
- GORD
- Dyspepsia
Contraindications:
Sodium-restricted diets
Phenylketonuria (PKU)
What are the indications for use of Magnesium hydroxide (Mylanta/Milk of magnesia)?
Administration: oral tablet, powder
- Indigestion
- GORD
- Constipation
What are the indications for use of Misoprostol (Cytotec)?
Administration: oral tablet
- PUD
- Prevention of NSAID-induced ulcers
- Termination of second trimester pregnancy
Contraindications:
Cerebrovascular or coronary artery disease
Predisposition to diarrhoea or dehydration
Pregnancy
What are the indications for use of Hyoscine butylbromide (Buscopan)?
Administration: oral tablet, IV, IM
- GI spasm
- Renal and biliary spasm
- Aid in GI radiology or endoscopy
- Irritable bowel syndrome
Contraindications:
Children < 6 years old
Glaucoma
Achalasia
Prostatic hypertrophy
What are the indications for use of Mebeverine (Colofac)?
Administration: oral tablet
- Irritable bowel syndrome (IBS)
Contraindications:
Angina
Lactose intolerance
What are the indications for use of Bisacodyl (Bisalax)?
Administration: oral tablet, suppository
- Constipation
- Bowel preparation
Contraindications:
Intestinal obstruction
Acute abdominal conditions (e.g. appendicitis)
Inflammatory bowel condition
Dehydration, hypokalaemia
What are the indications for use of Hysoscine hydrobromide (Kwells tablets/Travacalm)?
Administration: oral tablet, injection
- Motion sickness
- Premedication to dry excess respiratory tract secretion (injection)
- Diarrhoea
What are the indications for use of Metoclopramide (Maxolon)?
Administration: oral tablet, IV, IM
- Nausea and vomiting
- Gastric stasis
- Difficult small intestinal intubation
- Migraine with nausea and vomiting (with paracetamol)
Contraindications:
Phaeochromocytoma
Parkinson’s disease
Depression
Children
What are the indications for use of Ondansetron (Zofran)?
Administration: oral tablet, IV, IM
- Nausea and vomiting
Contraindications:
Phenylketonuria
What are the indications for use of Docusate (Coloxyl)?
Administration: oral tablet
- Constipation
- Prevent straining following rectal surgery and acute perianal disease
Take tablets with plenty of fluid.
What are the indications for use of Loperamide (Imodium)?
Administration: oral tablet, capsule
- Diarrhoea
- Intestinal stoma (to reduce frequency and fluidity of motions)
Contraindications:
Phenylketonuria (PKU)
Children (unless for chronic diarrhoea)
Dysentery
Hepatic impairment
What are the indications for use of Simethicone (De-Gas)?
Administration: oral capsule
- Flatulence
- Functional gastric bloating
- Post-operative gas pain
What are the indications for use of Orlistat (Xenical)?
Administration: oral capsule
- Adjunct to lifestyle modification in obese adults
Contraindications:
Vitamin deficiency
Pancreatic enzyme deficiency states
Major GI surgery
Malabsorption syndrome
Cholestasis
Pregnancy
Must be combined with low-fat diet. Fat-soluble vitamin supplementation (D and E) is recommended due to lack of absorption.
What are the indications for use of Phentermine (Duromine)?
Administration: oral capsule
- Adjunct to lifestyle modification in obese adults
Contraindications:
Hyperthyroidism
Peptic ulcer
History of drug misuse
Prostatic hypertrophy
Epilepsy
Cardiac disease
Elderly patients
Pregnancy
Can only be used for 3 weeks due to development of tolerance. Cannot be combined with other weight loss drugs or antidepressants (MAO inhibitors) due to excessive catecholamine release.
